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Artigos de revistas sobre o assunto "OER reaction"
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Rahman, Sheikh Tareq, Kyong Yop Rhee e Soo-Jin Park. "Nanostructured multifunctional electrocatalysts for efficient energy conversion systems: Recent perspectives". Nanotechnology Reviews 10, n.º 1 (1 de janeiro de 2021): 137–57. http://dx.doi.org/10.1515/ntrev-2021-0008.
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Abstract Electrocatalysts play a significant performance in renewable energy conversion, supporting several sustainable methods for future technologies. Because of the successful fabrication of distinctive oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) electrocatalysts, bifunctional ORR/OER and HER/OER electrocatalysts have become a hot area of contemporary research. ORR, OER, and HER have gained considerable attention because of their strong performance in different energy conversion and storage devices, including water-splitting devices, fuel cells, and metal–air rechargeable batteries. Therefore, the development of effective nanostructured multifunctional electrocatalysts for ORR, OER, and HER is necessary; and there is a demand for their industrialization for sustainable energy technology. In this review, details of current improvements in multifunctional catalysts for ORR/OER as well as HER/OER are presented, focusing on insight into the theoretical considerations of these reactions through investigation and estimation of different multifunctional catalysts. By analyzing the universal principles for various electrochemical reactions, we report a systematic scheme to clarify the recent trends in catalyzing these reactions over various types of nanostructure catalysts. The relevant reaction pathways and the related activity details for these reactions in the current literature are also included. Overall, the current demands and future outlines for improving the prospects of multifunctional electrocatalysts are discussed.
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Yan, Zhenwei, Shuaihui Guo, Zhaojun Tan, Lijun Wang, Gang Li, Mingqi Tang, Zaiqiang Feng, Xianjie Yuan, Yingjia Wang e Bin Cao. "Research Advances of Non-Noble Metal Catalysts for Oxygen Evolution Reaction in Acid". Materials 17, n.º 7 (3 de abril de 2024): 1637. http://dx.doi.org/10.3390/ma17071637.
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Water splitting is an important way to obtain hydrogen applied in clean energy, which mainly consists of two half-reactions: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). However, the kinetics of the OER of water splitting, which occurs at the anode, is slow and inefficient, especially in acid. Currently, the main OER catalysts are still based on noble metals, such as Ir and Ru, which are the main active components. Hence, the exploration of new OER catalysts with low cost, high activity, and stability has become a key issue in the research of electrolytic water hydrogen production technology. In this paper, the reaction mechanism of OER in acid was discussed and summarized, and the main methods to improve the activity and stability of non-noble metal OER catalysts were summarized and categorized. Finally, the future prospects of OER catalysts in acid were made to provide a little reference idea for the development of advanced OER catalysts in acid in the future.
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Morales, Dulce M., Mariya A. Kazakova, Maximilian Purcel, Justus Masa e Wolfgang Schuhmann. "The sum is more than its parts: stability of MnFe oxide nanoparticles supported on oxygen-functionalized multi-walled carbon nanotubes at alternating oxygen reduction reaction and oxygen evolution reaction conditions". Journal of Solid State Electrochemistry 24, n.º 11-12 (1 de junho de 2020): 2901–6. http://dx.doi.org/10.1007/s10008-020-04667-2.
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Abstract Successful design of reversible oxygen electrocatalysts does not only require to consider their activity towards the oxygen reduction (ORR) and the oxygen evolution reactions (OER), but also their electrochemical stability at alternating ORR and OER operating conditions, which is important for potential applications in reversible electrolyzers/fuel cells or metal/air batteries. We show that the combination of catalyst materials containing stable ORR active sites with those containing stable OER active sites may result in a stable ORR/OER catalyst if each of the active components can satisfy the current demand of their respective reaction. We compare the ORR/OER performances of oxides of Mn (stable ORR active sites), Fe (stable OER active sites), and bimetallic Mn0.5Fe0.5 (reversible ORR/OER catalyst) supported on oxidized multi-walled carbon nanotubes. Despite the instability of Mn and Fe oxide for the OER and the ORR, respectively, Mn0.5Fe0.5 exhibits high stability for both reactions.
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Hong, Yu-Rim, Sungwook Mhin, Jiseok Kwon, Won-Sik Han, Taeseup Song e HyukSu Han. "Synthesis of transition metal sulfide and reduced graphene oxide hybrids as efficient electrocatalysts for oxygen evolution reactions". Royal Society Open Science 5, n.º 9 (setembro de 2018): 180927. http://dx.doi.org/10.1098/rsos.180927.
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The development of electrochemical devices for renewable energy depends to a large extent on fundamental improvements in catalysts for oxygen evolution reactions (OERs). OER activity of transition metal sulfides (TMSs) can be improved by compositing with highly conductive supports possessing a high surface-to-volume ratio, such as reduced graphene oxide (rGO). Herein we report on the relationship between synthetic conditions and the OER catalytic properties of TMSs and rGO (TMS–rGO) hybrids. Starting materials, reaction temperature and reaction time were controlled to synergistically boost the OER catalytic activity of TMS–rGO hybrids. Our results showed that (i) compared with sulfides, hydroxides are favourable as starting materials to produce the desired TMS–rGO hybrid nanostructure and (ii) high reaction temperatures and longer reaction times can increase physico-chemical interaction between TMSs and rGO supports, resulting in highly efficient OER catalytic activity.
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Kim, Yohan, Seongmin Kim, Minyoung Shim, Yusik Oh, Kug-Seung Lee, Yousung Jung e Hye Ryung Byon. "Alteration of Oxygen Evolution Mechanisms in Layered LiCoO2 Structures By Intercalation of Alkali Metal Ions". ECS Meeting Abstracts MA2022-01, n.º 34 (7 de julho de 2022): 1356. http://dx.doi.org/10.1149/ma2022-01341356mtgabs.
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The word ‘Sustainability’, including carbon neutrality, has dominated the direction of social development over the past decade. In particular, energy conversion reactions through electrochemical methods are one of the efficient methods of obtaining small carbon footprint fuels. The oxygen evolution reaction (OER) is a key step in determining the overall reaction efficiency of fuel-related electrochemical reactions such as CO2 reduction reaction and H2 evolution reaction. However, electron transfer is sluggish for OER due to 4 electrons per one O2 molecule. This promotes multiple studies on the metal oxide electrocatalyst structure. The Alkali-transition metal oxides with the layered structure are one of the attractive OER electrocatalyst series. For example, lithium cobalt oxide (LiCoO2, LCO) presented OER activity through Li+ extraction (delithiation) from the lattice structure. In this work, we investigated the insertion effect of large alkaline cations (A+: Na+, K+, and Cs+) at the delithiated LCO for OER activity and stability. The intercalations of hydrated Na+ and K+ induced significant phase transformation of the delithiated LCO structure. In addition, the relative ratio between Co and alkali metal species determined the average Co oxidation state of LCO. We found that OER activity was improved in the order of Li+ < Na+ < K+, which was associated with the increased Co valence state and the Co-O bond covalency. Consistently, density functional theory (DFT) simulation also predicted the formation of efficient OER active sites by the K+ insertion. In comparison, Cs+ insertion exhibited the highest OER activity and demonstrated different OER processes. Due to the larger Cs+ size, the cation insertion was predominantly achieved at the delithiated LCO surface, resulting in imposing tensile strain to the surface edge. This catalyst showed the significant pH dependency on the OER property, suggesting the lattice-oxygen-based pathway for LCO. However, the bulk structure was preserved with little phase transformation, demonstrating better OER stability than others. In the presentation, I will discuss the catalytic activity responsible for the cation sizes and two different mechanisms in detail. Figure 1
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Wan, Xin, Yingjie Song, Hua Zhou e Mingfei Shao. "Layered Double Hydroxides for Oxygen Evolution Reaction towards Efficient Hydrogen Generation". Energy Material Advances 2022 (7 de setembro de 2022): 1–17. http://dx.doi.org/10.34133/2022/9842610.
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Electrochemical water splitting is one of the effective ways to obtain highly pure hydrogen. However, as one of the two half reactions, oxygen evolution reaction (OER) has a high overpotential, resulting in the low-energy utilization efficiency. Therefore, numerous electrocatalysts have been developed to reduce the energy barrier of OER. Among them, layered double hydroxides (LDHs) are excellent OER electrocatalysts with flexible composition and structure, which have been widely investigated in the past decade. Recent studies have been focusing on the identification of active sites for LDHs during OER process, trying to reveal clear reaction mechanism for designing more efficient LDHs electrocatalysts. Hence, this review tries to discuss the advances in identifying active site of LDHs based OER electrocatalysts for efficient hydrogen generation. We first introduce the effect of structure, composition, and defects to the OER performance of LDHs. Furthermore, main attention is paid on the active sites and mechanisms during OER, especially the coordination structures and catalytic mechanisms of active sites. At the end of this review, we put forward the existing problems and shortcomings in this fields, and propose the corresponding solutions, aiming to further promote the development of outstanding OER electrocatalysts towards efficient hydrogen production.
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Fukushima, Tomohiro, Masaki Itatani e Kei Murakoshi. "(Invited) Evaluation of Oxygen Evolution Reaction Electrodes through Machine-Learning Analysis and in-Situ Electrochemical Spectroscopy". ECS Meeting Abstracts MA2024-02, n.º 59 (22 de novembro de 2024): 4023. https://doi.org/10.1149/ma2024-02594023mtgabs.
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To enhance the catalysis of the oxygen evolution reaction (OER) at water electrolysis electrodes, it is imperative to eliminate the energy-consuming processes involved in multiple electron and proton transfer reactions. We propose employing a combination of machine-learning analysis of electrochemical activity and in-situ electrochemical Raman observation for the OER electrodes. The OER behavior can be categorized based on the contributions of Ni-OH and Ni-OOH, which serve as key OER intermediates. This information is utilized to elucidate the OER behavior through energetic and intermediate analyses. The presented study provides the direction for designing active OER catalysis in the future.
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Chae, Sangwoo, Akihito Shio, Tomoya Kishida, Kosuke Furutono, Yumi Kojima, Gasidit Panomsuwan e Takahiro Ishizaki. "Synthesis of High-Entropy Perovskite Hydroxides as Bifunctional Electrocatalysts for Oxygen Evolution Reaction and Oxygen Reduction Reaction". Materials 17, n.º 12 (17 de junho de 2024): 2963. http://dx.doi.org/10.3390/ma17122963.
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Oxygen reduction reaction (ORR) and oxygen evolutionc reaction (OER) are important chemical reactions for a rechargeable lithium–oxygen battery (LOB). Recently, high-entropy alloys and oxides have attracted much attention because they showed good electrocatalytic performance for oxygen evolution reaction (OER) and/or oxygen reduction reaction (ORR). In this study, we aimed to synthesize and characterize CoSn(OH)6 and two types of high-entropy perovskite hydroxides, that is, (Co0.2Cu0.2Fe0.2Mn0.2Mg0.2)Sn(OH)6 (CCFMMSOH) and (Co0.2Cu0.2Fe0.2Mn0.2Ni0.2)Sn(OH)6 (CCFMNSOH). TEM observation and XRD measurements revealed that the high-entropy hydroxides CCFMMSOH and CCFMNSOH had cubic crystals with sides of approximately 150–200 nm and crystal structures similar to those of perovskite-type CSOH. LSV measurement results showed that the high-entropy hydroxides CCFMMSOH and CCFMNSOH showed bifunctional catalytic functions for the ORR and OER. CCFMNSOH showed better catalytic performance than CCFMMSOH.
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Lin, Shiru, Haoxiang Xu, Yekun Wang, Xiao Cheng Zeng e Zhongfang Chen. "Directly predicting limiting potentials from easily obtainable physical properties of graphene-supported single-atom electrocatalysts by machine learning". Journal of Materials Chemistry A 8, n.º 11 (2020): 5663–70. http://dx.doi.org/10.1039/c9ta13404b.
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The oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) are three critical reactions for energy-related applications, such as water electrolyzers and metal–air batteries.
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Wu, Hengbo, Jie Wang, Wei Jin e Zexing Wu. "Recent development of two-dimensional metal–organic framework derived electrocatalysts for hydrogen and oxygen electrocatalysis". Nanoscale 12, n.º 36 (2020): 18497–522. http://dx.doi.org/10.1039/d0nr04458j.
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Developing efficient and low-cost electrocatalysts with unique nanostructures is of great significance for improved electrocatalytic reactions, including the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR).
Teses / dissertações sobre o assunto "OER reaction"
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Chen, Junsheng. "Ternary Metal Oxide/(Oxy)Hydroxide for Efficient Oxygen Evolution Reaction". Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/25536.
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Novel clean energy conversion and storage technologies, such as electrochemical water splitting and metal-air battery, play significant roles in the future clean energy society. Oxygen evolution reaction (OER), as the fundamental reaction of these technologies, is crucial for their practical application. However, OER process is sluggish since the complex reaction process (multi-electron and multi-intermediate involved reaction). Developing efficient and affordable OER electrocatalysts remains a great challenge. Recently, the multimetal incorporation strategy has aroused extensive research interest since it can effectively enhance the catalytic performance of the catalysts. Nevertheless, there are still many scientific questions to be answered for such materials systems, such as the reaction mechanism and the optimum element composition. In this thesis, earth-abundant transition metals Cobalt and iron were selected as the basic elements. Cheap and abundant metals Vanadium, Chromium, and Tungsten were chosen as the incorporation elements respectively because of their unique d orbital structure in oxidation state. Their oxides/(oxy)hydroxides were elaborately designed and synthesised. The OER performance of the incorporated materials display a huge improvement. A variety of characterisations were employed to investigate the electrochemical properties of the materials. Theoretical calculations were also applied and combined with the characterisation observation to explain the reaction mechanism and the role of the incorporation element. Practical electrical water electrolyser devices were built up to determine the synthesised OER electrocatalysts in a real situation. Specifically, a facile electrodeposition catalysts synthesis method was developed, which can rapidly manufacture electrodes with efficient OER electrocatalysts on a large scale.
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Mamtani, Kuldeep. "Carbon-based Materials for Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER) in Acidic Media". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu149376896628355.
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Wu, Qi-Long. "Defect Based Three-Dimensional Hierarchical Porous Carbons for Efficient Oxygen Reduction Reaction". Thesis, Griffith University, 2022. http://hdl.handle.net/10072/419073.
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The energy crisis and environmental pollution are the two major global issues caused by the excessive utilization of fossil fuels. In recent decades, developing renewable energy via electrocatalytic conversion technology has been considered as a feasible approach to replace fossil fuels. However, the scarcity and high price of commercial catalysts (e.g., Pt/C catalyst for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER); RuO2 for oxygen evolution reaction (OER)) seriously hinder the industrialization of the electrocatalytic technology. Therefore, it is highly urgent to develop efficient and cost-effective electrocatalysts to accelerate the further development of renewable energy technologies.
Defective carbon-based materials (DCMs) have recently been considered as one of the most promising alternatives to replace precious metal electrocatalysts with the merits of high-performance, abundance and low-cost. However, structural tailoring of carbon defects at atomic scales poses great challenges in regulating defect types and density to maximize the activity.
In this thesis, we aim to develop new synthetic strategies to precisely control the structural reconstruction and surface modification of carbons, which involves a series of intensive thermal redox reactions and oxygen atom modification.
Specifically,
For the first research work, an interfacial self-corrosion strategy was developed to control the removal and reconstruction of carbon atoms via a series of thermal redox reactions of ZnO quantum dots and formed CO2 gas in confined carbon cavity, which results an ultra-dense carbon defects on carbons (HDPC). Such ultra-dense carbon defects (2.46 × 1013 cm-2) were served as efficient active sites for oxygen reduction, resulting in an excellent catalyst in both base and acid media (half-wave potentials of 0.90 or 0.75 V in 0.1 M KOH or HClO4).
For the second research work, in consideration of the difficulty of identification of active sites on hierarchical porous carbon, we employed graphene as a model catalyst to control carbon defect density and surface oxygen groups (O-groups) on graphene. Firstly, the as-synthesized catalyst with the highest defect density (DG-30) shows the best four electronic pathway oxygen reduction reaction (4e-ORR) performance. After modifying O-groups (named as O-DG-30), the ORR of the catalyst turns into a 2e- pathway. Moreover, the dynamic evolution processes and catalytic mechanisms were revealed through multiple in-situ technologies and theoretical simulations. This work further demonstrated the significance of defect density towards ORR performance.
In summary, we develop a new synthetic strategy to fabricate ultra-dense defect density on carbon, emphasizing the importance of defect density towards ORR. Based on this knowledge, we further control defect density and surface chemical environment on graphene to identify the real active sites of DCMs. This thesis provides new knowledge and perspectives in materials synthesis and electrocatalytic mechanisms via 1) developing a new synthetic methodology for ultra-dense defects construction and 2) identifying the real active site and catalytic mechanism of DCMs.Thesis (Masters)
Master of Philosophy (MPhil)
School of Eng & Built Env
Science, Environment, Engineering and Technology
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Zou, Yu. "Supported Composite Electrocatalysts for Energy Conversion Applications". Thesis, Griffith University, 2022. http://hdl.handle.net/10072/417198.
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Increasing energy demand and environmental awareness have promoted the development of efficient and environment-friendly hydrogen technologies. Water electrolysis (2𝐻2𝑂→2𝐻2+𝑂2) is a promising way to store renewable electricity generated by solar or wind energy into chemical fuel in the form of H2. Water electrolysis is comprised of a hydrogen evolution reaction (HER) on the cathode and an oxygen evolution reaction (OER) on the anode. For both HER and OER, highly catalytic active electrocatalysts are required to lower the overpotentials and to speed up the sluggish kinetics. To date, noble metal catalysts are still the most efficient electrocatalysts for these two reactions, but their high cost and low abundance on Earth limit the scalable application of water electrolysis. Therefore, investigation of alternative catalysts with low cost and high electrocatalytic activity is urgently needed.
This thesis focuses on alkaline electrocatalytic HER, as well as related reactions such as OER, and hydrazine oxidation(HzOR)-assistant HER. In terms of material design, the components are introduced to improve conductivity and mass transfer, as well as boost the intrinsic catalytic activity. Moreover, the mechanism was investigated through exploring the link between structure and performance, as well using density functional theory (DFT) calculations.
The first two experimental chapters employed a two-dimensional (2D) material, MXene, as support. In Chapter 2, ruthenium single atoms were incorporated onto ultrathin Ti3C2Tx MXene nanosheets to unlock its electrocatalytic activity. The RuSA@Ti3C2Tx presented a 1 A cm−2 HER current density with an over potential of 425.7 mV, outperforming the commercial Pt/C benchmark. Operando Raman test under HER potential showed the different protonation level between RuSA@Ti3C2Tx and Ti3C2Tx, suggesting the different hydrogen absorption energy of the oxygen terminal on the Ti3C2Tx basal plane. Finally, the theoretical calculations confirmed that the RuSA not only facilitates water dissociation, but also modulates the hydrogen After increasing the Ru content and conducting electroreduction, RuTi alloy nanoclusters were constructed on the surface of Ti3C2Tx. Surprisingly, the RuTi@Ti3C2Tx showed better performance in HER, and excellent hydrazine oxidation reaction (HzOR) performance. The overpotential to attain a current density of 10 mA cm−2 for HER was only 14 mV, lower than that of the commercial Pt/C. The HzOR catalytic activity also outperformed most reported work. In addition, the overall hydrazine spitting was conducted in an H-type electrolytic cell, demonstrating superior thermodynamic advantage and good stability.
Defect-abundant active carbon (AC-DCD) as support was prepared by the hydrothermal reaction with dicyanamide. Then, the Ru nanoparticles were grown on the surface. Compared to the catalyst with pristine AC as support prepared under same conditions, Ru600@AC-DCD presented a larger electrochemical special area with strain-abundant Ru nanoparticles. Ru600@AC-DCD delivered excellent HER performance in alkaline media, and good catalytic properties in acidic and neutral media.
Finally, another novel metal@carbon composite, Ni nanoparticles encapsulated in graphite carbon layers, was synthesized by directly annealing the Ni-imidazole framework precursors at 350 °C in H2/Ar. By tuning the annealing time under H2/Ar flow, Ni nanoparticles with different crystalline phases were synthesized. These Ni@C samples are di-function electrocatalysts for HER and OER in alkaline condition. The mixed-phase catalyst mix2-Ni@C delivered the highest activity to catalyze HER, while the pure hcp phase catalyst hcp-Ni@C showed best OER activity. This work provided a practical method to prepare low-cost difunctional electrocatalysts for overall water electrolysis.
In summary, the thesis innovatively contributes to the knowledge in material science and water electrolysis in the aspects of: (i) designing novel supported composite electrocatalysts with high catalytic activity for HER, OER, and HzOR; (ii) monitoring the changing of surface terminal by operando Raman spectroscopy to verify the HER mechanism; (iii) development of metal nanostructures, like RuTi alloy, hcp phase Ni and mixed-phase Ni, via facile methods, and investigation of their unique properties; and (iv) application of large current HER and exploration of the kinetics under different potentials.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
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Duan, Yan. "Understanding the oxygen evolution reaction (OER) for Co based transition metal oxides / hydroxides in alkaline electrolytes". Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS416.
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Le développement d'électrocatalyseurs efficaces pour la réaction de libération d'oxygène (OER) est important pour améliorer l'efficacité globale du processus d'électrolyse de l'eau. Les oxydes / hydroxydes de métaux de transition présentent une activité et une stabilité raisonnables lorsqu’utilisés dans un milieu alcalin. Ils ont le potentiel de remplacer les oxydes à base d'Ir et de Ru. Comprendre la réaction d’OER pour les oxydes / hydroxydes de métaux de transition dans les électrolytes alcalins aide à la conception d'électrocatalyseurs peu coûteux et très efficaces. Avec trois travaux différents sur les oxydes / hydroxydes à base de Co, cette thèse approfondit la compréhension des propriétés de surface des matériaux et des propriétés interfaciales sur la cinétique de la réaction d’OER. Tout d'abord, la substitution au fer régule par exemple la configuration des cations métalliques dans LaCoO3. Cela ajuste la covalence de la liaison oxygène 2p – métal 3d et améliore les performances. Deuxièmement, la substitution au Ni dans ZnCo2O4 modifie la position relative du centre de la bande O 2p et du centre de la bande métallique dans un environnement octahédrique MOh. Cela modifie la stabilité et la possibilité pour l'oxygène du réseau de participer à la réaction de dégagement d’oxygène. Enfin, en étudiant les séries La1-xSrxCoO3, CoOOH et CoOOH contenant Fe, l'impact de l'électrolyte sur les paramètres de la cinétique de réaction a été exploré. Avec une meilleure compréhension de la façon dont les propriétés des matériaux et l'environnement dynamique influencent l'activité et le mécanisme des OER, nous pouvons obtenir des catalyseurs de OER plus efficaces pour une meilleure infrastructure énergétiqueThe development of efficient electrocatalysts to lower the overpotential of oxygen evolution reaction (OER) is of fundamental importance in improving the overall efficiency of fuel production by water electrolysis. Among a plethora of catalysts being studied on, transition metal oxides / hydroxides that exhibit reasonable activity and stability in alkaline electrolyte have been identified as catalysts to potentially overpass the activity of expensive Ir- and Ru- based oxides. Understanding the OER for transition metal oxides / hydroxides in alkaline electrolytes paves the way for better design of low cost and highly efficient electrocatalysts. This dissertation, with three different work on Co-based oxides / hydroxides, studies and deepens the understanding of the bulk properties, surface properties of materials and interfacial properties on OER. Firstly, with Fe substitution, it addresses tuning the eg configuration of metal cations in LaCoO3 where adjusting the metal 3d oxygen 2p covalency can bring benefits to the OER performance. Secondly, with Ni substitution in ZnCo2O4, it demonstrates a change in relative position of O p-band and MOh d-band centre which induces a change in stability as well as the possibility for lattice oxygen to participate in the OER. Finally, with La1-xSrxCoO3 series, CoOOH and Fe-containing CoOOH as examples, the impact of the electrolyte has been explored by the study of reaction kinetics parameters. With a better understanding of how material properties and dynamic environment influence the OER activity and mechanism, we can obtain more efficient OER catalysts for better energy infrastructure
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Stevens, Michaela. "Fundamentals and Industrial Applications: Understanding First Row Transition Metal (Oxy)Hydroxides as Oxygen Evolution Reaction Catalysts". Thesis, University of Oregon, 2017. http://hdl.handle.net/1794/22633.
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Intermittent renewable energy sources, such as solar and wind, will only be viable if the electrical energy can be stored efficiently. It is possible to store electrical energy cleanly by splitting the water into oxygen (a clean byproduct) and hydrogen (an energy dense fuel) via water electrolysis. The efficiency of hydrogen production is limited, in part, by the high kinetic overpotential of the oxygen evolution reaction (OER). OER catalysts have been extensively studied for the last several decades. However, no new highly active catalyst has been developed in decades. One reason that breakthroughs in this research are limited is because there have been many conflicting activity trends. Without a clear understanding of intrinsic catalyst activity it is difficult to identify what makes catalysts active and design accordingly. To find commercially viable catalysts it is imperative that electrochemical activity studies consider and define the catalyst’s morphology, loading, conductivity, composition, and structure.
The research goal of this dissertation is twofold and encompasses 1) fundamentally understanding how catalysis is occurring and 2) designing and developing a highly active, abundant, and stable OER catalyst to increase the efficiency of the OER. Specifically, this dissertation focuses on developing methods to compare catalyst materials (Chapter II), understanding the structure-compositional relationships that make Co-Fe (oxy)hydroxide materials active (Chapter III), re-defining activity trends of first row transition metal (oxy)hydroxide materials (Chapter IV), and studying the role of local geometric structure on active sites in Ni-Fe (oxy)hydroxides (Chapter V). As part of a collaboration with Proton OnSite, the catalysts studied are to be integrated into an anion exchange membrane water electrolyzer in the future.
This dissertation includes previously published and unpublished co-authored material.10000-01-01
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Al-Mamun, Mohammad. "Rational Design of Nanostructured Earth-Abundant Electrocatalysts for Energy Conversion Applications". Thesis, Griffith University, 2016. http://hdl.handle.net/10072/365651.
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Electrocatalysis contributes to a huge extent in a large array of research fields and applications, including corrosion science, electroanalytical sensors, wastewater treatment, electro-organic synthesis and more importantly, energy conversion applications. Of the many electrocatalytic processes, the oxygen evolution reaction (OER) and triiodide reduction reaction (IRR) are of widespread importance in electrochemical cells and dye-sensitised solar cells (DSSCs). OER is a key half reaction in electrochemical water splitting, direct solar-to-electricity driven water splitting and metal-air batteries. The high cost of efficient benchmark electrocatalysts, such as RuO2 or IrO2, however, is a major drawback of OERs. While, IRR plays a significant role in DSSCs, which must be electrocatalysed at the counter electrode to complete the external circuit in real devices and thereby successfully convert solar energy to electricity. Traditionally, Pt is accepted as an ideal benchmark electrocatalyst for IRR, but its high cost and scarcity limits broad application of DSSCs. Thus, extensive effort has been made to find active alternative electrocatalysts with low-cost, high electrocatalytic activity and excellent stability for OER and IRR to the noble metals (Ru, Ir and Pt). Therefore, a rational design of earth-abundant and low-cost electrocatalysts for OER and IRR maintains a paramount significance for energy conversion applications to meet the constantly growing demand for energy supply.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Bernicke, Michael [Verfasser], Ralph [Akademischer Betreuer] Krähnert, Peter [Gutachter] Strasser e Michael [Gutachter] Bron. "Mesoporous oxides as efficient catalysts for the electrocatalytic oxygen evolution reaction (OER) / Michael Bernicke ; Gutachter: Peter Strasser, Michael Bron ; Betreuer: Ralph Krähnert". Berlin : Technische Universität Berlin, 2016. http://d-nb.info/1156010195/34.
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Terry, Alexandre. "New mixed 3d metal-based oxyfluorinated materials as anodic catalysts for water splitting : from elaboration to mechanistic study". Electronic Thesis or Diss., Le Mans, 2024. https://cyberdoc-int.univ-lemans.fr/Theses/2024/2024LEMA1029.pdf.
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Si l'hydrogène est un vecteur énergétique prometteur pour le stockage durable de l'énergie, sa production doit reposer sur des technologies sans carbone. L’électrolyse de l’eau qui consiste à dissocier l'eau via un courant électrique issu d’énergies renouvelables est idéal pour produire un hydrogène vert. Toutefois, ce processus est entravé par une cinétique lente de la réaction OER (Oxygen Evolution Reaction, 2H2O ⇋ O2 + 4H+ + 4e-) à l'anode, nécessitant un apport d’énergie supplémentaire pour assurer un rendement énergétique satisfaisant. Ainsi, des catalyseurs, généralement des oxydes d'iridium et de ruthénium, sont utilisés pour réduire cette énergie en facilitant le transfert d'électrons et de protons impliqués dans la réaction OER. Toutefois, l’utilisation de ces métaux de plus en plus rares freine l'évolution de cette technologie. Pour y remédier, des catalyseurs à base d'oxydes et d'oxyhydroxydes de métaux de transition 3d, économiques et abondants, ont été mis au point pour l’électrolyse de l’eau en milieu alcalin et présentent des performances élevées. Ce travail de thèse présente la synthèse de nouveaux composés oxyfluorés à base d’éléments éco-compatibles et abordables en utilisant une voie d’élaboration simple et directe en deux étapes pour une application en tant qu'électrocatalyseur anodique dans un électrolyseur alcalin.L'étude initiale porte sur des catalyseurs oxyfluorés enrichis en fer, issus de la décomposition thermique à l'air ambiant de (Co1-xFex)2+Fe3+F5(H2O)7 (0 ≤ x ≤ 0,72). Les résultats montrent que la teneur en cobalt peut être réduite de 20% sans affecter les performances OER, permettant d'atteindre un surpotentiel de 320 mV à 10 mA.cm-2, une activité massique de 110 A.g-1 à 1,55 V vs. RHE et une grande stabilité. La deuxième partie de la thèse vise à améliorer les propriétés catalytiques du composé référence Co0,5Fe0,5O0,5F1,5 en remplaçant le cobalt par du nickel, connu pour son activité OER. La solution solide (Co(1-x)/2Nix/2)2+Fe0,5O0,5F1,5-y(OH)y (y ≤ 0.3) a été obtenue par décomposition thermique (Co1-xNix)2+FeF5(H2O)7 (0 ≤ x ≤ 1). La dernière partie vise à évaluer les performances de ces matériaux ainsi que d’étudier leur mécanisme de réaction. La composition x = 0,5 présente les meilleures performances, avec un faible surpotentiel de 290 mV à 10 mA.cm-2 et une activité spécifique de 3,9 A.m-2 de surface BET à 1,5 V vs. RHE. L'origine des propriétés catalytiques exceptionnelles de (Co0.25Ni0.25)2+Fe3+0.5O0,5F1,3(OH)0,2, mis en évidence via entre autres des analyses in-situ/operando ont été employées, proviendrait de la synergie entre Co et Ni, et l’implication d’oxygènes du réseau dans le mécanisme (LOM), contournant les limites théoriques liées au mécanisme conventionnelIf hydrogen is a promising energy vector for sustainable energy storage, its production must rely on carbon-free technologies. Water splitting powered by green electricity is ideal for producing a decarbonized energy carrier from water. However, this process is hampered by the sluggish kinetics of the oxidation evolution reaction (OER, 2H2O ⇋ O2 + 4H+ + 4e-) at the anode, requiring extra energy to ensure a suitable production rate. Catalysts, usually iridium and ruthenium oxides, are employed to reduce the energy requirement by facilitating electron and proton transfer involved in OER, but these metals are scarce, limiting the scalability of this technology. To overcome this, oxides and oxyhydroxides catalysts based on cost-effective and abundant 3d transition metal-based have been developed for alkaline water splitting, presenting high performance. In this way, this work presents the synthesis of new oxyfluorides with eco-compatible and affordable elements using a simple and straightforward two-step synthetic route for application as OER electrocatalyst in alkaline electrolyte.The initial study focuses on iron-enriched oxyfluoride catalysts from thermal decomposition under ambient air of (Co1-xFex)2+Fe3+F5(H2O)7 (0 ≤ x ≤ 0.72). Results show that cobalt content can be reduced by 20% without affecting OER performance, achieving an overpotential of 320 mV at 10 mA.cm-2, a mass activity of 110 A.g-1 at 1.55 V vs. RHE and high stability. The second part aims to enhanced the catalytic properties of Co0.5Fe0.5O0.5F1.5 reference by substituting cobalt with nickel, known for its OER activity. The (Co(1-x)/2Nix/2)2+Fe0.5O0.5F1.5-y(OH)y (y ≤ 0.3) solid solution have been obtained by thermal decomposition (Co1-xNix)2+FeF5(H2O)7 (0 ≤ x ≤ 1). The final section assesses the performance of these materials and studies their reaction mechanism. The x = 0.5 composition shows the best performance, with a low overpotential of 290 mV at 10 mA.cm-2 and a specific activity of 3.9 A.m-2 of BET surface area at 1.5 V vs. RHE. The origin of the exceptional catalytic properties of (Co0.25Ni0.25)2+Fe3+0.5O0.5F1.3(OH)0.2, highlighted via in-situ/operando analyses, among others, were employed, would stem from the synergy between Co and Ni, and the involvement of lattice oxygens in the mechanism (LOM), circumventing the theoretical limits linked to the conventional mechanism
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Kumar, Kavita. "Catalyseurs sans métaux nobles pour pile à combustible régénérative". Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2284/document.
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Le dihydrogène (H2) se présente comme le futur vecteur énergétique pour une économie basée sur des ressources propres et respectueuses de l'environnement. Il est le combustible idéal de la pile à combustible régénérative constituée de deux entités : un électrolyseur pour sa production, et une pile à combustible pour sa conversion directe en énergie électrique. Ce système présente l'avantage d'être compact et autonome. Cependant, l'amélioration de l'activité catalytique des matériaux, leur stabilité et l'élimination de métaux nobles dans leur composition sont nécessaires. Des catalyseurs bifonctionnels à base de métaux de transition associés au graphène ont alors été synthétisés. L'interaction oxyde-graphène a été étudiée sur un catalyseur Co3O4/NRGO. À faible teneur en cobalt, l'interaction entre les atomes de cobalt de l'oxyde et les atomes d'azote greffés sur les plans de graphène a été observée par voltammétrie cyclique. Cette interaction est responsable d'une diminution de la taille des nanoparticules de cobaltite et de l'activité de celles-ci vis-à-vis de la réaction de réduction du dioxygène (RRO). La substitution du cobalt par le nickel dans des structures de type spinelle (NiCo2O4/RGO) obtenu par voie solvothermale, a permis d'améliorer les performances électrocatalytiques vis-à-vis de la RRO et de la RDO. Ce matériau et un autre de type Fe-N-C préparé en collaboration avec un laboratoire de l'Université Technique de Berlin ont servi de cathode dans des études préliminaires réalisées en configuration pile à combustible alcaline à membrane échangeuse d'anion (SAFC)Hydrogen, as an environmentally friendly future energy vector, is a non-toxic and convenient molecule for regenerative fuel cell, which connects two different technologies: an electrolyzer for H2 production, and a fuel cell for its direct conversion to electric energy. This kind of system possesses many advantages, such as lightness, compactness and more autonomy. However, improvement of activity and durability of electrode materials free from noble metals in their composition is needed. Thereby, bifunctional catalysts composed of transition metals deposited onto graphene-based materials were synthesized. The interaction between the metal atom of the oxide and the graphene doped heteroatom in the Co3O4/NRGO catalyst was investigated physicochemically. With a low cobalt loading, the interaction between cobalt and nitrogen was characterized by cyclic voltammetry, which revealed that it was responsible for decreasing the oxide nanoparticle size, as well as increasing the material activity towards the oxygen reduction reaction (ORR). The substitution of Co by Ni in the spinel structure (NiCo2O4/RGO) obtained by solvothermal synthesis, allowed the enhancement of the electrocatalytic performances towards the ORR and OER. Moreover, this catalyst as well as another material prepared in collaborative program with a lab from Technical University of Berlin were used as cathode in preliminary studies undertaken on solid alkaline fuel cell (SAFC)
Livros sobre o assunto "OER reaction"
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Kerekes, Amália. Mehr oder Weininger: Eine Textoffensive aus Österreich/Ungarn. Wien: Braumüller, 2005.
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Fattahi, Mir Taher. Emil Abderhalden (1877-1950), die Abwehrfermente: Ein langer Irrweg oder wissenschaftlicher Betrug? Berlin: Uni-Edition, 2006.
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Issel, Wolfgang. Die Wiederaurarbeitung von bestrahlten Kernbrennstoffen in der Bundesrepublik Deutschland: Technologische Chance oder energiepolitischer Zwang. Frankfurt am Main: P. Lang, 2003.
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Henriksen, Niels Engholm, e Flemming Yssing Hansen. Bimolecular Reactions, Dynamics of Collisions. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198805014.003.0004.
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This chapter discusses the dynamics of bimolecular collisions within the framework of (quasi-)classical mechanics as well as quantum mechanics. The relation between the cross-section and the reaction probability, which can be calculated theoretically from a (quasi-)classical or quantum mechanical description of the collision, is described in terms of classical trajectories and wave packets, respectively. As an introduction to reactive scattering, classical two-body scattering is described and used to formulate simple models for chemical reactions, based on reasonable assumptions for the reaction probability. Three-body (and many-body) quasi-classical scattering is formulated and the numerical evaluation of the reaction probability is described. The relation between scattering angles and differential cross-sections in various frames is emphasized. The chapter concludes with a brief description of non-adiabatic dynamics, that is, situations beyond the Born–Oppenheimer approximation where more than one electronic state is in play. A discussion of the so-called Landau–Zener model is included.
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Wiffen, Philip, Marc Mitchell, Melanie Snelling e Nicola Stoner. Adverse drug reactions and drug interactions. Oxford University Press, 2017. http://dx.doi.org/10.1093/med/9780198735823.003.0002.
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This chapter provides an overview of adverse drug reactions and drug interactions for pharmacists and other healthcare professionals. It provides a practical guide to determining whether a reaction is related to the drug or disease. A classification of adverse drug reactions is given and how this relates to immediate management of the reaction and future drug choices is discussed. Tips are given on how to discuss adverse drug reactions and explain risks to patients. Mechanisms of drug interactions are covered and a practical guide for predicting and managing interactions is given.
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Henriksen, Niels Engholm, e Flemming Yssing Hansen. From Microscopic to Macroscopic Descriptions. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198805014.003.0002.
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This chapter discusses bimolecular reactions from both a microscopic and macroscopic point of view. The outcome of an isolated reactive scattering event can be specified in terms of an intrinsic fundamental quantity, the reaction cross-section that can be measured in a molecular beam experiment. It depends on the quantum states of the molecules as well as the relative velocity of reactants and products. The relation between the cross-section and the macroscopic rate constant is derived. The rate constant is a weighted average of the product between the relative speed of the reactants and the reaction cross-section. The chapter concludes with the special case of thermal equilibrium, where the velocity distributions for the molecules are the Maxwell–Boltzmann distribution. The expression for the rate constant at temperature T is reduced to a one-dimensional integral over the relative speed of the reactants.
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Ferner, Robin, e Anthony Cox. Drug-induced neurological disease. Editado por Patrick Davey e David Sprigings. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199568741.003.0240.
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An adverse drug reaction is defined as ‘an appreciably harmful or unpleasant reaction, resulting from an intervention related to the use of a medicinal product; adverse effects usually predict hazard from future administration and warrant prevention, or specific treatment, or alteration of the dosage regimen, or withdrawal of the product’ (p. 1255, Edwards IR and Aronson JK. Adverse drug reactions: Definitions, diagnosis, and management. Lancet 2000; 356: 1255–9). Adverse drug reactions can cause or contribute to central and peripheral nervous system disorders, including traumatic, infective, neoplastic, demyelinating, and vascular diseases.
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Misbah, Siraj. Suspected anaphylaxis. Editado por Patrick Davey e David Sprigings. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199568741.003.0075.
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A type I IgE-mediated systemic allergic reaction is characterized by a constellation of symptoms which are due to widespread histamine release and which comprise acute-onset urticaria, angioedema, bronchospasm, and hypotension. While a mild reaction may be limited to localized urticaria and/or angioedema, a full-blown allergic reaction associated with systemic features is best described as anaphylaxis. The term ‘anaphylactoid’, previously used to denote non-IgE-mediated systemic allergic reactions, is no longer recommended for use.
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Henriksen, Niels E., e Flemming Y. Hansen. Theories of Molecular Reaction Dynamics. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198805014.001.0001.
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This book deals with a central topic at the interface of chemistry and physics—the understanding of how the transformation of matter takes place at the atomic level. Building on the laws of physics, the book focuses on the theoretical framework for predicting the outcome of chemical reactions. The style is highly systematic with attention to basic concepts and clarity of presentation. Molecular reaction dynamics is about the detailed atomic-level description of chemical reactions. Based on quantum mechanics and statistical mechanics or, as an approximation, classical mechanics, the dynamics of uni- and bimolecular elementary reactions are described. The first part of the book is on gas-phase dynamics and it features a detailed presentation of reaction cross-sections and their relation to a quasi-classical as well as a quantum mechanical description of the reaction dynamics on a potential energy surface. Direct approaches to the calculation of the rate constant that bypasses the detailed state-to-state reaction cross-sections are presented, including transition-state theory, which plays an important role in practice. The second part gives a comprehensive discussion of basic theories of reaction dynamics in condensed phases, including Kramers and Grote–Hynes theory for dynamical solvent effects. Examples and end-of-chapter problems are included in order to illustrate the theory and its connection to chemical problems. The book has ten appendices with useful details, for example, on adiabatic and non-adiabatic electron-nuclear dynamics, statistical mechanics including the Boltzmann distribution, quantum mechanics, stochastic dynamics and various coordinate transformations including normal-mode and Jacobi coordinates.
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Ross, John, Igor Schreiber e Marcel O. Vlad. Determination of Complex Reaction Mechanisms. Oxford University Press, 2006. http://dx.doi.org/10.1093/oso/9780195178685.001.0001.
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In a chemical system with many chemical species several questions can be asked: what species react with other species: in what temporal order: and with what results? These questions have been asked for over one hundred years about simple and complex chemical systems, and the answers constitute the macroscopic reaction mechanism. In Determination of Complex Reaction Mechanisms authors John Ross, Igor Schreiber, and Marcel Vlad present several systematic approaches for obtaining information on the causal connectivity of chemical species, on correlations of chemical species, on the reaction pathway, and on the reaction mechanism. Basic pulse theory is demonstrated and tested in an experiment on glycolysis. In a second approach, measurements on time series of concentrations are used to construct correlation functions and a theory is developed which shows that from these functions information may be inferred on the reaction pathway, the reaction mechanism, and the centers of control in that mechanism. A third approach is based on application of genetic algorithm methods to the study of the evolutionary development of a reaction mechanism, to the attainment given goals in a mechanism, and to the determination of a reaction mechanism and rate coefficients by comparison with experiment. Responses of non-linear systems to pulses or other perturbations are analyzed, and mechanisms of oscillatory reactions are presented in detail. The concluding chapters give an introduction to bioinformatics and statistical methods for determining reaction mechanisms.
Capítulos de livros sobre o assunto "OER reaction"
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Bi, Songhu, Zhen Geng, Liming Jin, Mingzhe Xue e Cunman Zhang. "Porous Heterogeneous Sulfide Nickel/Nickel Iron Alloy Catalysts for Oxygen Evolution Reaction of Alkaline Water Electrolysis at High Current Density". In Proceedings of the 10th Hydrogen Technology Convention, Volume 1, 116–21. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8631-6_13.
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AbstractAlkaline water electrolysis is the important pathway for the green hydrogen production, where oxygen evolution reaction (OER) is the rate-limiting step due to the sluggish reaction kinetics. Transition metal heterogeneous catalyst is the kind of important OER catalyst for alkaline water electrolysis due to its good performance, low price and environmental friendliness. In this work, the porous sulfide nickel@nickel iron alloy catalyst (i.e. NM/NS@Ni3Fe) is prepared by the designed high-temperature vulcanization and multi-step electrodeposition method. The NM/NS@Ni3Fe catalyst exhibits an outstanding OER performance in an alkaline environment, with a low potential of 1.53 V at high current density of 1000 mA cm−2 and a low Tafel slope of 89 mV dec−1. The excellent OER performance is attributed to the unique electronic structure of Ni3S2/Ni3Fe heterogeneous interface and the catalyst layer with porous structure. The results indicate that Ni3S2 provides good electronic conductivity and the low electronegativity S atoms increase the formation of oxygen vacancies, which effectively improves the OER performance. In addition, the hydrophilic and porous structure of the electrode facilitates bubbles release and electrolyte flow at high current density. It provides the guidance for the design of porous heterogeneous OER catalysts with good-performance.
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Deng, Jiayao, Xiao Hu, Gnauizhi Xu, Zhanfeng Deng, Lan Yang, Ding Chen, Ming Zhou e Boyuan Tian. "The Preparation of Iridium-Based Catalyst with Different Melting Point-Metal Nitrate and Its OER Performance in Acid Media". In Proceedings of the 10th Hydrogen Technology Convention, Volume 1, 61–68. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8631-6_6.
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AbstractOxygen evolution reaction (OER) is the main factor limiting the large-scale development of proton-exchange membrane (PEM) hydrogen production. It is urgent to develop catalysts with excellent OER catalytic performance and stability. Herein, several Iridium-based catalysts were prepared by simple mixing and calcination, the OER properties of catalysts with different melting points of nitrates as calcinating additives were investigated. The RbNO3 treated catalyst displayed a low overpotential(η) of 297.6 mV versus RHE, which is lower than the catalyst calcinated without nitrate (323.8 mV vs. RHE). Moreover, the RbNO3 treated catalyst displayed good acid stability over 20 h Chronopotentiometric test. The high OER catalytic activity and stability of RbNO3 treated catalyst may be attribute to the smaller nanoparticle morphology, pure IrO2 structure and high electrochemical surface area (ECSA), which increase the number of active sites and the intrinsic catalytic activity. This work indicated that the catalyst with excellent OER performance can be obtained by selecting nitrate with moderate melting point as the calcinating additive. Nitrates (like RbNO3) treated catalyst with excellent catalytic activity and stability has good application prospect in hydrogen production of PEM water splitting.
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Bell, Alexis T. "Chapter 3. Understanding the Effects of Composition and Structure on the Oxygen Evolution Reaction (OER) Occurring on NiFeOx Catalysts". In Energy and Environment Series, 79–116. Cambridge: Royal Society of Chemistry, 2018. http://dx.doi.org/10.1039/9781788010313-00079.
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Andronov, Mikhail, Natalia Andronova, Michael Wand, Jürgen Schmidhuber e Djork-Arné Clevert. "Curating Reagents in Chemical Reaction Data with an Interactive Reagent Space Map". In Lecture Notes in Computer Science, 21–35. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-72381-0_3.
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AbstractThe increasing use of machine learning and artificial intelligence in chemical reaction studies demands high-quality reaction data, necessitating specialized tools enabling data understanding and curation. Our work introduces a novel methodology for reaction data examination centered on reagents - essential molecules in reactions that do not contribute atoms to products. We propose an intuitive tool for creating interactive reagent space maps using distributed vector representations, akin to word2vec in Natural Language Processing, capturing the statistics of reagent usage within datasets. Our approach enables swift assessment of reagent action patterns and identification of erroneous reagent entries, which we demonstrate using the USPTO dataset. Our contributions include an open-source web application for visual reagent pattern analysis and a table cataloging around six hundred of the most frequent reagents in USPTO annotated with detailed roles. Our method aims to support organic chemists and cheminformatics experts in reaction data curation routine.
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Cao, Dong, Mengyao Ma e Peng Gao. "Trifunctional Electrocatalysts for the Hydrogen Evolution Reaction (HER), Oxygen Evolution Reaction (OER), and Oxygen Reduction Reaction (ORR)". In Multi-functional Electrocatalysts, 407–33. Royal Society of Chemistry, 2024. http://dx.doi.org/10.1039/9781837674497-00407.
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The hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) play pivotal roles in energy devices such as electrochemical water splitting, rechargeable zinc–air batteries, and fuel cells. However, the slow kinetics lead to a large overpotential being required for these three reactions because they all involve multi-electron transfers. In addition, the cathode of rechargeable zinc–air batteries needs to be switched between ORR and OER during the charging and discharging processes, so it is necessary to use dual-function ORR/OER electrocatalysts. The application of OER/HER bifunctional electrocatalysts could reduce the costs of water-splitting devices. Therefore, to advance the application of rechargeable zinc–air batteries and water electrolyzers, it is of great importance to develop trifunctional electrocatalysts with excellent catalytic activity for ORR, OER, and HER. In this chapter, the approaches to the classification and construction of trifunctional catalysts are explored in depth, which is important for their future development.
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Khrizanforova, Vera V., e Yulia H. Budnikova. "MOFs and their Derived Structures for Multifunctional Electrocatalysis". In Advanced Catalysts Based on Metal-organic Frameworks (Part 2), 162–91. BENTHAM SCIENCE PUBLISHERS, 2023. http://dx.doi.org/10.2174/9789815136029123010007.
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Multifunctional catalysis attracts great interest due to the opportunity to apply one compound in different types of reactions, and particularly its role in energy conversion reactions, such as hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). The requirements of several catalysts are combined in one molecule, which allows utilizing these compounds at both cathode and anode sides for a variety of energy devices. However, seeking optimal catalysts with multifunctional applications and appropriate activity and durability is a difficult task. One of the promising candidates is metal-organic frameworks due to their unique structure and high-specific surface area. Utilization of MOFs and their derivatives as multifunctional catalysts for HER/OER, OER/ORR, HER/ORR/OER, and corresponding energy provision technologies, such as water splitting electrolyzers, metal-ion batteries, is the top area of modern research. Herein, the recent examples of MOF-based electrocatalysts for HER/OER/ORR activity in terms of their bifunctionality and trifunctionality and further application at both cathode and anode sides of water electrolyzer and metal-ion battery are summarized.
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Thomassen, Magnus, e Svein Sunde. "Electrocatalysts for Oxygen Evolution Reaction (OER)". In PEM Electrolysis for Hydrogen Production, 35–64. CRC Press, 2015. http://dx.doi.org/10.1201/b19096-4.
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"Electrocatalysts for Oxygen Evolution Reaction (OER)". In PEM Electrolysis for Hydrogen Production, 47–76. CRC Press, 2016. http://dx.doi.org/10.1201/b19096-7.
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Pataniya, Pratik M., Ayushi Shah, Pooja Sharma e C. K. Sumesh. "Trifunctional Electrocatalysts for the Hydrogen Evolution Reaction (HER), Oxygen Evolution Reaction (OER), and Urea Oxidation Reaction (UOR)". In Multi-functional Electrocatalysts, 434–69. Royal Society of Chemistry, 2024. http://dx.doi.org/10.1039/9781837674497-00434.
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The quest for alternative fuels has been investigated for many years owing to the storage constraints on fossil fuels and petroleum and the excessive carbon dioxide emissions following combustion. Recently, the use of hydrogen as a fuel has attracted substantial attention. Electrochemical water splitting has gained prominence as a crucial method of production that can be utilized to create clean hydrogen fuel that is sustainable, renewable, affordable, and efficient. Trifunctional electrocatalysts are substances with simultaneous catalytic activity for many electrochemical processes. Several energy conversion and storage applications require the simultaneous electrocatalytic activities of the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and an additional reaction, such as the urea oxidation reaction (UOR), which is why the design of such catalysts is of great interest. This chapter introduces the basic principles of electrochemical water splitting along with a detailed explanation of HER-, OER-, and UOR-based water-splitting mechanisms. How heteroatom doping, heterostructures, cocatalyst deposition, and surface modification can improve hydrogen generation is discussed, and the factors that affect the electrochemical performance are also examined. A promising research field with enormous potential for a range of energy conversion and storage applications is the creation of effective trifunctional electrocatalysts.
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Singha, Debal Kanti, Tapan Ping, Biswajit Nayak, Smruti Vardhan Purohit e Bikash Kumar Jena. "Metal–Organic Framework-derived Bifunctional Electrocatalysts". In Multi-functional Electrocatalysts, 226–65. Royal Society of Chemistry, 2024. http://dx.doi.org/10.1039/9781837674497-00226.
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This chapter provides an introduction to the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) and discusses the fundamental aspects and their significance in different applications. Measurements of different electrochemical parameters needed for the measurement of the OER and ORR performance of a catalyst are considered. A novel class of advanced porous hybrid materials has emerged: metal–organic frameworks (MOFs) with variable pore sizes and large surface areas characterized by various periodic patterns. Because of their immense porosity and mechanical and thermal durability, they are used in a wide variety of applications. However, the low electrical conductivity and poor stability of MOFs make their use in electrocatalysis difficult. The benefits of using MOF-derived materials as bifunctional electrocatalysts for OER and ORR are discussed.
Trabalhos de conferências sobre o assunto "OER reaction"
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Hameed, Areeba, Khulood Logade, Naba Ali, Priya Ghosh, Sadiya Shafath, Sumaiya Salim, Anchu Ashok, Anand Kumar e Mohd Ali H. Saleh Saad. "Highly active Bifunctional Lamo3 (M=Cr, Mn, Fe, Co, Ni) Perovskites for Oxygen Reduction and Oxygen Evolution Reaction in Alkaline Media". In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0106.
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Lanthanum based electrocatalytically active perovskites, LaMO3 (M=Cr, Mn, Fe, Co, Ni), were synthesized using a single step solution combustion synthesis technique. The perovskites showed exceptional performance for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline medium. Based on the experimental results and literature survey, it is suggested that the exceptional activity of Mn and Co based lanthanum perovskite catalyst could be due to the optimum stabilization of reaction intermediates involved in the rate-determining step (RDS) of ORR/OER. According to crystal field theory (CFT), the d-orbital of transition metals are affected by the octahedral arrangement of six negative charges around it. The d orbital degenerates by splitting into two high energy (eg) and three lower energy orbitals (t2g) while maintaining the same average energy level. The rate-determining step in the ORR/OER reaction that based on the eg orbital filling of B site transition metal cations If the d-electrons are less, the valence state goes up and lowering the eg orbital filling that results in strong adsorption of oxygenated species on the B site (strong B-OH bond). This strong bonding limits the overall reaction rate by the slow desorption of OH and its derivatives during ORR/OER. Similarly, too high eg filling causes weak adsorption of oxygenated species that limits the reaction through the slow adsorption of reactants. Therefore, to enhance the activity of ORR/OER reaction it is required to balance the adsorption and desorption of the reactants and the intermediate respectively. The better way is to optimize the eg orbital filling to be nearly 1 (eg = 1).Based on the experimental results and literature survey, it is suggested that the exceptional activity of Mn and Co based lanthanum perovskite catalyst could be due to the optimum stabilization of reaction intermediates involved in the rate-determining step (RDS) of ORR and OER.
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Panigrahy, Bharati, B. Ramachandra Rao e Vipul Kumar Maheshwari. "Development and Demonstration of In-House Design Green Hydrogen Production Technologies with Reduced CAPEX and OPEX". In ADIPEC. SPE, 2024. http://dx.doi.org/10.2118/222255-ms.
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Abstract Design of highly efficient cost effective and self-supported bi-functional electrocatalyst for the production of green Hydrogen is significant for renewable and sustainable energy conversion to achieve future carbon neutral. Meanwhile, as we know that the overall water splitting is an uphill reaction requires 285.8 kJ of energy, corresponds to the HHV of hydrogen, state-of-the-art developments are necessary to greatly improve the efficiency by rationally designing non-precious metal-based robust bi-functional catalysts for promoting both the cathodic hydrogen evolution and anodic oxygen evolution reactions. The performance of metal phosphide towards hydrogen and oxygen evolution was examined under application relevant conditions in an alkaline and anion exchange membrane (AEM) electrolyzer cell stack. The in-house designed stacked electrolyzer exhibited stable performances with a hydrogen production rate of few Nm3 per hour without any decay, pave the path towards large scale application with substantial reduction in CAPEX and OPEX cost. Key Words: Water splitting, Green Hydrogen, Electrolyzer, Electrolysis, HER, OER
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Motyka, Elaine, Erin Volpe, Stefan Roeseler, Ryan Plessinger, Tyler Noyes, Chenyu Li, Habin Park, Paul Kohl, William Mustain e Jonathan Kweder. "The Effect of FELTMETAL™ Porous Transport Layer Structure on Performance of Anion Exchange Membrane Water Electrolyzers". In ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/gt2024-129232.
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Abstract The porous transport layer (PTL), or gas diffusion layer (GDL), is a critical component in the performance of anion exchange membrane water electrolyzers (AEMELs) for hydrogen production and hydrogen supply. This work focuses on how the structure of FELTMETAL™ (FM) affects the critical functions of the oxygen evolution reaction (OER) electrode in an AEMEL. As a sintered-particle material with high levels of open pores, FM has high total porosity which positively affects mass transport of the gas and water from the PTL but increases the electrical resistivity and contact resistance. Due to the nature of the high-aspect ratio particles in FM, it also has high surface area which improves electrical properties and enables high current density during AEMEL operation. However, sintered materials typically have a trade-off between total porosity and pore size which can lead to mass transport issues if the pore size and distribution are too tight. Previous experimental electrolysis work determined that increasing the %-density of FM from 18%-density to 60%-density favorably increased current density at a given applied voltage, but it was likely that mass transport issues related to bubble formation and removal caused variation in performance and a decrease in current density over time. This work ultimately aimed to determine the effect of particle size on the structure of the FM PTL (pore size, total porosity, surface area) on AEMEL performance (current density, applied voltage, voltage stability over time, overpotentials). The study evaluated OER PTL FM with distinctly different %-densities and particle size distributions of Ni-alloy HastelloyX. The structures were characterized by metallography and bubble point testing. The AEMEL performance was characterized by polarization and electrochemical imprudence spectroscopy (EIS). Because the work focuses on the OER PTL structure, other key components of the experimental AEMEL were not varied, using standard commercial materials. It was found that the using a finer particle size distribution had a significant positive effect on polarization responses, specifically voltage at 1A/cm2, steady state voltage, and activation overpotential. The finer particle structure likely has increased total pore number and area-% open pores. It is possible that FM PTL materials comprised of finer fiber can enable performance improvement at a lower %-density, reducing the material required to make the PTL.
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Mohammed, Habiba, Zainab Muhammad Shuaibu, Binta Asabe Muhammad, Bello Aminu Aminu e Maryam Albashir. "Assessment of Teacher Network for Girls Education (TEN-G) Project in Kaduna State, Nigeri". In Tenth Pan-Commonwealth Forum on Open Learning. Commonwealth of Learning, 2022. http://dx.doi.org/10.56059/pcf10.2671.
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This study assesses impact of the TEN-G program rolled out and implemented by Commonwealth of Learning (COL) and Centre for Girls’ Education (CGE) respectively, aimed at providing greater access to quality education and training through open, distance and technology-enabled learning in reaction to the school disruption caused by the Covid-19 pandemic in Kaduna state , Nigeria. The project has dual objective of training female teachers on Open Educational Resources and bridging learning gaps so as to return all female students back to school after the pandemic. Hence, four programs were carried out, namely; teachers’ training on Open Educational Resources, Interactive Radio Instruction (IRI) and Safe Space Clubs. We employed both quantitative (questionnaire) and qualitative (interviews and FGDs) instruments of data collection for this study. Our analysis revealed that, teachers capacity on the use of technology to access OER has risen from 19% to 100%, over 90% of school girls returned to school after the pandemic; a success which only 12.8% of our respondents feel is not as a result of the IRI. Safe space clubs were found to have bridged learning gap necessitated by COVID-19 pandemic and has improved their learning abilities. It is therefore recommended that; the TEN-G project should be sustained in order to accommodate more schools and more learners across Kaduna state and the entire northern Nigeria.
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Ahsan, Syed Saad, e David Erickson. "Microfluidic Photocatalytic Water-Splitting Reactors". In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-87860.
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In this work, we present a novel microfluidic photocatalytic water-splitting reactor. Optofluidics offers advantages over conventional reactors in terms of improved photon transfer efficiency and mass transfer efficiency and are therefore the ideal platform for photocatalytic reactions. Our device is a planar optofluidic device which we used to study the kinetics of Platinum-Impregnated Titanium Oxide as the oxygen and hydrogen producing photocatalyst redox mediated by Iodide/Iodate species. We deposit our catalysts via a sol-gel method while the platinum co-catalyst is added by wet impregnation via reduction in Sodium Borohydride. The reactions are performed under a 100W Hg lamp and reaction rates are inferred by measuring the depletion of the two Iodine species via UV-vis absorption spectrophotometry. Our results indicate that reaction rates and efficiencies can be enhanced by using an optofluidic platform as opposed to the conventional slurry reactor used in previous experiments for this class of reaction. We believe that the micro-optofluidic platform of our device offers the benefit of measuring the kinetic properties of these class of reactions quickly and cheaply for the goals of further optimization.
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Matsumura, Yukihiko, Go Tsujimoto e Takuro Konishi. "Determination of Heat of Reaction in Supercritical Water". In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44073.
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The heat of reactions in supercritical water is difficult to measure. Our group fabricated a new reactor to enable the measurement of this heat with extremely high accuracy. The system consisted of a single, insulated tube reactor. The reaction heat was determined by the temperature change of the flow caused by the heat. We found, however, that the heat loss of the reactor compromised the measurements accuracy. Though small, this factor was impossible to completely remove, especially when the reaction was fast or the flow was slow. To compensate, we measured the heat loss and used the measured value to correct our calculation of the reaction heat. The direct measurements of the reaction heat agreed well with the calculated values, with relative error of only around 5% up to reaction heats as large as 100 kJ/kg-water.
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Gokulakrishnan, P., S. Kwon, A. J. Hamer, M. S. Klassen e R. J. Roby. "Reduced Kinetic Mechanism for Reactive Flow Simulation of Syngas/Methane Combustion at Gas Turbine Conditions". In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90573.
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The reduced kinetic mechanism for syngas/methane developed in the present work consists of a global reaction step for fuel decomposition in which the fuel molecule breaks down into CH2O and H2. A detailed CH2O/H2/O2 elementary reaction sub-set is included as the formation of intermediate combustion radicals such as OH, H, O, HO2, and H2O2 is essential for accurate predictions of non-equilibrium phenomena such as ignition and extinction. Since the chemical kinetics of H2 and CH2O are the fundamental building blocks of any hydrocarbon oxidation, the inclusion of detailed kinetic mechanisms for CH2O and H2 oxidation enables the reduced mechanism to predict over a wide range of operating conditions provided the reaction rate parameters of fuel-decomposition reaction is optimized over those conditions. Therefore, the rate coefficients for the fuel-decomposition step are estimated and optimized for the ignition delay time measurements of CH4, H2, CH4/H2, CH4/CO and CO/H2 mixtures available in the literature over a wide range of pressures, temperatures and equivalence ratios that are relevant to gas turbine operating conditions. The optimized reduced mechanism, consisting of 15 species and around 40 reactions, is able to predict the ignition delay time and laminar flame speed measurements of CH4, H2, CH4/H2, CH4/CO and CO/H2 mixtures fairly well over a wide range conditions. The model predictions are also compared with that of GRI3.0 mechanism. The reduced kinetic mechanism predicts the ignition delay time of CH4 and CH4/H2 mixtures far better than GRI mechanism at higher pressures. To demonstrate the predictive capability of the model in reactive flow systems, the reduced mechanism was implemented in Star-CD/KINetics commercial code using a RANS turbulence model to simulate CH4/air premixed combustion in a backward facing step. The CFD model predictions of the stable species in the exhaust gas agree well with the GRI mechanism predictions in a chemical reactor network modeling by approximating the backward facing step with a series of perfectly-stirred reactor and plug-flow reactor.
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Du, T. Z., Chun-Ho Liu e Y. B. Zhao. "Large-Eddy Simulation of Reactive Pollutant Dispersion Over Street Canyons of Different Aspect Ratios". In ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting collocated with the ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/fedsm2014-21252.
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In urban areas, pollutants are emitted from vehicles then disperse from the ground level to the downstream urban canopy layer (UCL) under the effect of the prevailing wind. For a hypothetical urban area in the form of idealized street canyons, the building-height-to-street-width (aspect) ratio (AR) changes the ground roughness which in turn leads to different turbulent airflow features. Turbulence is considered an important factor for the removal of reactive pollutants by means of dispersion/dilution and chemical reactions. Three values of aspect ratio, covering most flow scenarios of urban street canyons, are employed in this study. The pollutant dispersion and reaction are calculated using large-eddy simulation (LES) with chemical reactions. Turbulence timescale and reaction timescale at every single point of the UCL domain are calculated to examine the pollutant removal. The characteristic mechanism of reactive pollutant dispersion over street canyons will be reported in the conference.
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Schaffer, W. M., e T. V. Bronnikova. "Modeling Peroxidase-Oxidase Interactions". In ASME 2011 Dynamic Systems and Control Conference and Bath/ASME Symposium on Fluid Power and Motion Control. ASMEDC, 2011. http://dx.doi.org/10.1115/dscc2011-5946.
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Reactive oxygen species (ROS) and peroxidase-oxidase (PO) reactions are Janus-faced contributors to cellular metabolism. At low concentrations, reactive oxygen species serve as signaling molecules; at high concentrations, as destroyers of proteins, lipids and DNA. Correspondingly, PO reactions are both sources and consumers of ROS. In the present paper, we study a well-tested model of the PO reaction based on horseradish peroxidase chemistry. Our principal predictions are these: 1. Under hypoxia, the PO reaction can emit pulses of hydrogen peroxide at apparently arbitrarily long intervals. 2. For a wide range of input rates, continuing infusions of ROS are transduced into bounded dynamics. 3. The response to ROS input is hysteretic. 4. With sufficient input, regulatory capacity is exceeded and hydrogen peroxide, but not superoxide, accumulates. These results are discussed with regard to the episodic nature of neurodevelopmental and neurodegenerative diseases that have been linked to oxidative stress and to downstream interactions that may result in positive feedback and pathology of increasing severity.
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Le Cong, Tanh, e Philippe Dagaut. "Kinetics of Natural Gas, Natural Gas/Syngas Mixtures Oxidation and Effect of Burnt Gas Recirculation: Experimental and Detailed Modeling". In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27146.
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The oxidation of methane-based fuels was studied experimentally in a fused silica jet-stirred reactor (JSR) operating at 1–10 atm, over the temperature range 900-1400 K, from fuel-lean to fuel-rich conditions. Similar experiments were performed in presence of carbon dioxide or syngas (CO/H2). A previously proposed kinetic reaction mechanism updated for modeling the oxidation of hydrogen, CO, methane, methanol, formaldehyde, and natural gas over a wide range of conditions including JSR, flame, shock tube, and plug flow reactor was used. A detailed chemical kinetic modeling of the present experiments was performed yielding a good agreement between the data and the modeling. Literature burning velocities and ignition delays were also modeled. Reaction paths analyses were used to delineate the important reactions influencing the kinetic of oxidation of the fuels in presence of variable amounts of CO2. The kinetic reaction scheme proposed helps determining the effect of the additives on the oxidation of methane.
Relatórios de organizações sobre o assunto "OER reaction"
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Knibb, Rebecca, Lily Hawkins e Dan Rigby. Food Sensitive Study: Wave Two Survey. Food Standards Agency, setembro de 2022. http://dx.doi.org/10.46756/sci.fsa.nyx192.
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Food hypersensitivities (FH) include food allergy, food intolerance and coeliac disease. Food allergy and coeliac disease involve an immune mediated reaction to certain foods; food intolerance is caused by a non-immune mediated reaction (such as an enzymatic or pharmacological effect). Each of these FHs result in unpleasant symptoms if the food is eaten in sufficient quantity, with food allergic reactions sometimes resulting in life-threatening symptoms. Management of FH by an individual or members of their family therefore involves constant vigilance and risk assessment to determine if a food is safe to eat. Research over the last twenty years has demonstrated that this burden, along with the unpredictable nature of FH reactions, has an impact on quality of life (QoL). QoL encompasses our emotions, physical health, the environment we live in, our social networks and day-to-day activities. FH has been shown to have an impact on many of these areas, however there are still research gaps. In particular, many studies focus on children, adolescents or parents rather than the adult population and little is known about those with food intolerances. In order to make a comprehensive characterisation and evaluation of the burden caused by living with FH, the day-to-day management of FH and associated inconveniences, the FSA has commissioned this project, led by Aston University. The project is called the FoodSensitive study and this report relates to findings for workstream one, a survey to assess the impact of FH on QoL. This survey was carried out in two waves, one year apart. This report covers the second wave and a comparison of wave one and two for those participants who completed both waves.
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Dong, Yi, LiJia Liu, Jianing Liu, Tianqi Liao, Jieru Zhou e Huaien Bu. Incidences of Adverse Reactions in BNT162b2: A Meta-analysis. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, janeiro de 2022. http://dx.doi.org/10.37766/inplasy2022.1.0043.
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Review question / Objective: This study searched PubMed, Cochrane Library, Web of Science, Embase Electronics, and other databases to collect healthy adults aged 16 and older, subjects with no previous history of COVID-19 infection, A randomized controlled trial of Pfizer's vaccine BNT162b2 versus placebo. Using RevMan5.4 software, meta-analysis was conducted to compare the effects of injection of BNT162b2 and placebo on the incidence of adverse reactions in healthy adults over 16 years of age. Main indexes include total incidence of adverse reactions, the incidence of local adverse reactions at the injection site (including red hot accessories), the incidence of systemic adverse reactions, including fever, headache, rash, urticaria, joint pain, muscle pain, gastrointestinal tract reaction, fatigue, cough, etc.), death rate, so as to provide a reference for clinical practice. Information sources: The following electronic databases will be searched from January 2020 to November 2021: PubMed, the Cochrane Library, Web of Science, Embase Electronics. In addition, reference lists of the included studies were manually searched to identify additional relevant studies.
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Smith, Donald L. Observations on the Effects of 252Cf Spontaneous-Fission Neutron Spectrum Uncertainties on Uncertainties in Calculated Spectrum-Average Cross Sections for Reactions in the Neutron Dosimetry Library IRDFF-II. IAEA Nuclear Data Section, novembro de 2022. http://dx.doi.org/10.61092/iaea.wx80-dm11.
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The Neutron Dosimetry Library IRDFF-II was released in January 2020, and was subsequently documented by an article published in the Nuclear Data Sheets by A. Trkov et al. The development of this library, under the auspices of the IAEA Nuclear Data Section, entailed extensive effort to assemble and examine the available, relevant experimental data, as well as to select and validate the best available cross-section evaluations, for some 110 neutron reaction processes included in this library. Part of the validation process for this library entailed comparing experimental and evaluated differential cross-sections as well as corresponding integral cross sections for a variety of integral neutron spectra considered to be relevant for fission and fusion neutron dosimetry purposes. Prominent among these spectra is the well-known 252Cf spontaneous-fission (s.f.) neutron spectrum that is considered to be a standard for both IRDFF-II and the ENDF/B libraries. Experimental and calculated uncertainties for all these data were considered in this validation process. The evaluated 252Cf s.f. neutron spectrum, owing to the manner in which it was developed, is considered to be largely independent of the evaluated neutron reaction cross sections in both of these libraries. Therefore, the uncertainties in calculated spectrum-average cross sections (SACS) stemming from evaluated cross-section uncertainties are considered to be largely independent from the uncertainties in the evaluated 252Cf s.f. neutron-spectrum itself. The present investigation sought specifically to examine systematic behaviors for the uncertainties of calculated neutron reaction SACS in IRDFF-II due exclusively to uncertainties in the 252Cf spectrum. This work was enabled by the availability of extensive calculations performed and documented by A. Trkov during development of the IRDFF-II Library. It was observed from the present investigation that the 252Cf s.f. neutron spectrum component of these calculated SAC uncertainties, for threshold reactions that exhibit relatively smooth cross-section behaviors, vary quite smoothly and predictably as a function of the parameter E50% (that neutron energy at which the reaction-rate integral for this neutron spectrum reaches 50% of the integral over the full energy range) for values of E50% from around 2 MeV up to almost 17 MeV. The behaviors observed in the present investigation for those reactions in IRDFF-II involving lower and higher values of E50% are less predictable owing to factors that are discussed in this report. This report also provides numerous tables and plots based on calculated results from the work of A. Trkov to illustrate these conclusions.
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Ahlquist, J. T., e N. N. Watkins. Modeling Continuous-Flow Reactor Improvements over Batch Reactions for Enzyme Catalyzed Microsphere Surface Reactions. Office of Scientific and Technical Information (OSTI), setembro de 2019. http://dx.doi.org/10.2172/1568027.
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Bordalo, Pedro, Nicola Gennaioli, Yueran Ma e Andrei Shleifer. Over-reaction in Macroeconomic Expectations. Cambridge, MA: National Bureau of Economic Research, agosto de 2018. http://dx.doi.org/10.3386/w24932.
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Syvash, Kateryna. AUDIENCE FEEDBACK AS AN ELEMENT OF PARASOCIAL COMMUNICATION WITH SCREEN MEDIA-PERSONS. Ivan Franko National University of Lviv, fevereiro de 2021. http://dx.doi.org/10.30970/vjo.2021.49.11062.
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Parasocial communication is defined as an illusory and one-sided interaction between the viewer and the media person, which is analogous to interpersonal communication. Among the classic media, television has the greatest potential for such interaction through a combination of audio and visual series and a wide range of television content – from newscasts to talent shows. Viewers’ reaction to this product can be seen as a defining element of parasociality and directly affect the popularity of a media person and the ratings of the TV channel. In this article we will consider feedback as part of parasocial communication and describe ways to express it in times of media transformations. The psychological interaction «media person – viewer» had been the focus of research by both psychologists and media experts for over 60 years. During the study, scientists described the predictors, functions, manifestations and possible consequences of paracommunication. One of the key elements of the formed parasocial connections is the real audience reaction. Our goal is to conceptualize the concept of feedback in the paradigm of parasocial communication and describe the main types of reactions to the media person in long-term parasocial relationships. The research focuses on the ways in which the viewer’s feedback on the television media person is expressed, bypassing the issue of classifying the audience’s feedback as «positive» and «negative». For this purpose, more than 20 interdisciplinary scientific works on the issue of parasocial interaction were analyzed and their generalization was carried out. Based on previous research, the types and methods of feedback in the television context are separated. With successful parasocial interaction, the viewer can react in different ways to the media person. The type of feedback will directly depend on the strength of the already established communication with the media person. We distinguish seven types of feedback and divide them into those that occur during or after a television show; those that are spontaneous or planned; aimed directly at the media person or third parties. We offer the following types of feedback from TV viewers: «talking to the TV»; telling about the experience of parasocial communication to others; following on social networks; likes and comments; imitation of behavior and appearance; purchase of recommended brands; fanart.
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da Silveira, Rava Azeredo, e Michael Woodford. Noisy Memory and Over-Reaction to News. Cambridge, MA: National Bureau of Economic Research, janeiro de 2019. http://dx.doi.org/10.3386/w25478.
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Kanner, Joseph, Mark Richards, Ron Kohen e Reed Jess. Improvement of quality and nutritional value of muscle foods. United States Department of Agriculture, dezembro de 2008. http://dx.doi.org/10.32747/2008.7591735.bard.
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Food is an essential to our existence but under certain conditions it could become the origin to the accumulative health damages. Technological processes as heating, chopping, mincing, grounding, promote the lipid oxidation process in muscle tissues and meat foodstuffs. Lipid oxidation occurred rapidly in turkey muscle, intermediate in duck, and slowest in chicken during frozen storage. Depletion of tocopherol during frozen storage was more rapid in turkey and duck compared to chicken. These processes developed from lipid peroxides produce many cytotoxic compounds including malondialdehyde (MDA). The muscle tissue is further oxidized in stomach conditions producing additional cytotoxic compounds. Oxidized lipids that are formed during digestion of a meal possess the potential to promote reactions that incur vascular diseases. A grape seed extract (1% of the meat weight) and butylated hydroxytoluene (0.2% of the lipid weight) were each effective at preventing formation of lipid oxidation products for 3 hours during co-incubation with cooked turkey meat in simulated gastric fluid (SGF). Polyphenols in the human diet, as an integral part of the meal prevent the generation and absorption of cytotoxic compounds and the destruction of essential nutrients, eg. antioxidants vitamins during the meal. Polyphenols act as antioxidants in the gastrointestinal tract; they scavenge free radicals and may interact with reactive carbonyls, enzymes and proteins. These all reactions results in decreasing the absorption of reactive carbonyls and possible other cytotoxic compounds into the plasma. Consumptions of diet high in fat and red meat are contributory risk factors partly due to an increase production of cytotoxic oxidized lipid products eg. MDA. However, the simultaneously consumption of polyphenols rich foods reduce these factors. Locating the biological site of action of polyphenols in the in the gastrointestinal tract may explain the paradox between the protective effect of a highly polyphenols rich diet and the low bioavailability of these molecules in human plasma. It may also explain the "French paradox" and the beneficial effect of Mediterranean and Japanese diets, in which food products with high antioxidants content such as polyphenols are consumed during the meal.
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Panizza, Ugo, e Dany Jaimovich. Procyclicality or Reverse Causality? Inter-American Development Bank, março de 2007. http://dx.doi.org/10.18235/0010973.
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There is a large literature showing that fiscal policy is either acyclical or countercyclical in industrial countries and procyclical in developing countries. Most of this literature is based on OLS regressions that focus on the correlation between a fiscal variable (usually the budget balance or expenditure growth) and either GDP growth or some measure of the output gap. This paper argues that such a methodology does not permit the identification of the effect of the business cycle on fiscal policy and hence cannot be used to estimate policy reaction functions. The paper proposes a new instrument for GDP growth and shows that, once GDP growth is properly instrumented, procyclicality tends to disappear.
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Ferreira, Clodomiro, e Stefano Pica. Households’ subjective expectations: disagreement, common drivers and reaction to monetary policy. Madrid: Banco de España, novembro de 2024. http://dx.doi.org/10.53479/38316.
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Using granular data on household subjective expectations for several countries, we uncover a robust positive reaction of inflation expectations to a contractionary monetary policy shock, a result at odds with standard equilibrium theories with nominal rigidities. We then investigate what lies behind such result. Although households disagree, their expectations are correlated in the cross-section. Two principal components account for a significant portion of the variance of all expectations. These components capture households’ perceptions of the sources of macroeconomic dynamics, with the first capturing either a supply-side view or an overall dislike for inflation, and the second component reflecting a perception about demand pressures. This structure of disagreement is stable across countries and over time and does not vary with demographic or socioeconomic characteristics. We then use these insights to identify two common factors driving expectations over time. These factors are consistent with a narrative based on perceived supply-side inflationary pressures after the invasion of Ukraine in February 2022, as well as with the overall downward inflation dynamics intensified by the reaction of the ECB.