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Статті в журналах з теми "Double Atom Catalyst"
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Kim, Seung-hoon, Ho Chang Song, Sung Jong Yoo, Jonghee Han, Kwan-Young Lee, and Hyung Chul Ham. "Impact of the dopant-induced ensemble structure of hetero-double atom catalysts in electrochemical NH3 production." Journal of Materials Chemistry A 10, no. 11 (2022): 6216–30. http://dx.doi.org/10.1039/d1ta08358a.
Повний текст джерелаАнотація:
Compared to Ru single atom catalyst, hetero-RuM (M = Fe, Os, and Ir) double atom catalysts showed improved N2RR activity with the help of dxz and dxy bonding orbital, caused by strain, dopant and configurational effects.
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Wu, Donghai, Bingling He, Yuanyuan Wang, Peng Lv, Dongwei Ma, and Yu Jia. "Double-atom catalysts for energy-related electrocatalysis applications: a theoretical perspective." Journal of Physics D: Applied Physics 55, no. 20 (January 31, 2022): 203001. http://dx.doi.org/10.1088/1361-6463/ac4b56.
Повний текст джерелаАнотація:
Abstract Due to the excellent activity, selectivity, and stability, atomically dispersed metal catalysts with well-defined structures have attracted intensive research attention. As the extension of single-atom catalyst, double-atom catalyst (DAC) featuring with the metal dimer anchored on a suitable substrate has recently emerged as a research focus for the energy-related electrocatalysis reactions. Due to the flexible dual-metal sites and the synergetic effect between the two metal atoms in DACs, there are more possibilities to adjust their geometrical configurations and electronic structures. The wide tunability of the active sites could offer more opportunities to optimize the binding strength of the reaction intermediates and thus the catalytic activity and/or selectivity of chemical reactions. Moreover, the neighboring metal sites provide a platform to perform more complex electrocatalysis reaction involving the chemical bond coupling. This review aims to summarize the recent advance in theoretical research on DACs for diverse energy-related electrocatalytic reactions. It starts with a brief introduction to DACs. Then an overview of the main experimental synthesis strategies of DACs is provided. Emphatically, the catalytic performance together with the underlying mechanism of the different electrocatalytic reactions, including nitrogen reduction reaction, carbon dioxide reduction reaction, oxygen reduction reaction, and oxygen and hydrogen evolution reactions, are highlighted by discussing how the outstanding attributes mentioned above affect the reaction pathway, catalytic activity, and product selectivity. Finally, the opportunities and challenges for the development of DACs are prospected to shed fresh light on the rational design of more efficient catalysts at the atomic scale in the future.
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Hao, Zhuo, Yangyang Ma, Yisong Chen, Pei Fu, and Pengyu Wang. "Non-Noble Metal Catalysts in Cathodic Oxygen Reduction Reaction of Proton Exchange Membrane Fuel Cells: Recent Advances." Nanomaterials 12, no. 19 (September 24, 2022): 3331. http://dx.doi.org/10.3390/nano12193331.
Повний текст джерелаАнотація:
The oxygen reduction reaction (ORR) is one of the crucial energy conversion reactions in proton exchange membrane fuel cells (PEMFCs). Low price and remarkable catalyst performance are very important for the cathode ORR of PEMFCs. Among the various explored ORR catalysts, non-noble metals (transition metal: Fe, Co, Mn, etc.) and N co-doped C (M–N–C) ORR catalysts have drawn increasing attention due to the abundance of these resources and their low price. In this paper, the recent advances of single-atom catalysts (SACs) and double-atom catalysts (DACs) in the cathode ORR of PEMFCs is reviewed systematically, with emphasis on the synthesis methods and ORR performance of the catalysts. Finally, challenges and prospects are provided for further advancing non-noble metal catalysts in PEMFCs.
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Wang, Yun, and Lihua Kang. "Selective Hydrogenation of Acetylene Catalysed by a B12N12 Cluster Doped with a Single Nickel Atom: A DFT Study." Catalysts 10, no. 1 (January 13, 2020): 115. http://dx.doi.org/10.3390/catal10010115.
Повний текст джерелаАнотація:
To obtain a catalyst based on a non-precious metal that can replace traditional palladium-based selective catalysts of acetylene hydrogenation, the catalytic performances of two different configurations of a B12N12 cluster doped with a single nickel atom were studied by a density functional theory computational approach. After analysing the effect that the adsorption of reactants onto the clusters has on the reaction path, we determined the lowest energy path for the acetylene double hydrogenation. Comparing the acetylene hydrogenation activities and ethylene product selectivities of the B11N12Ni and B12N11Ni clusters, which have different doping sites, we determined the activities of these two catalysts to be similar to each other; however, the B11N12Ni cluster was calculated to have higher selectivity for ethylene as a product. This difference may be related to the moderate adsorption of hydrogen and acetylene on the B11N12Ni cluster. As a new type of nickel-based single-atom catalyst, B11N12Ni clusters may have research value in the selective hydrogenation of acetylene.
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Mark, Brian L., and Michael NG James. "Anchimeric assistance in hexosaminidases." Canadian Journal of Chemistry 80, no. 8 (August 1, 2002): 1064–74. http://dx.doi.org/10.1139/v02-130.
Повний текст джерелаАнотація:
Configuration retaining glycosidases catalyse the hydrolysis of glycosidic bonds via a double displacement mechanism, typically involving two key active site carboxyl groups (Glu or Asp). One of the enzymic carboxyl groups functions as a general acidbase catalyst, the other acts as a nucleophile. Alternatively, configuration-retaining hexosaminidases from the sequence-related glycosidase families 18, 20, and 56 lack a suitably positioned enzymic nucleophile; instead, they use the carbonyl oxygen atom of the neighbouring C2-acetamido group of the substrate. The carbonyl oxygen atom of the 2-acetamido group provides anchimeric assistance to the enzyme catalyzed reaction by acting as an intramolecular nucleophile, attacking the anomeric center and forming a cyclized oxazolinium ion intermediate that is stereochemically equivalent to the glycosylenzyme intermediate formed in the "normal" double displacement mechanism. Although there is little sequence similarity between families 18, 20, and 56 hexosaminidases, X-ray crystallographic studies demonstrate that they have evolved similar catalytic domains and active site architectures that are designed to distort the bound substrate so that the C2-acetamido group can become appropriately positioned to participate in catalysis. The substrate distortion allows for a substrate-assisted catalytic reaction that displays all the general characteristics of the classic double-displacement mechanism including the formation of a covalent intermediate.Key words: glycoside hydrolase, hexosaminidase, glycosidase, substrate-assisted catalysis, anchimeric assistance.
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Bai, Lichen, Chia-Shuo Hsu, Duncan T. L. Alexander, Hao Ming Chen, and Xile Hu. "A Cobalt–Iron Double-Atom Catalyst for the Oxygen Evolution Reaction." Journal of the American Chemical Society 141, no. 36 (August 16, 2019): 14190–99. http://dx.doi.org/10.1021/jacs.9b05268.
Повний текст джерела
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Dinamarca, Robinson, Verónica Valles, Brenda Ledesma, Cristian H. Campos, Gina Pecchi, and Andrea Beltramone. "Magnetic Fe3O4@SiO2–Pt and Fe3O4@SiO2–Pt@SiO2 Structures for HDN of Indole." Materials 12, no. 23 (November 24, 2019): 3878. http://dx.doi.org/10.3390/ma12233878.
Повний текст джерелаАнотація:
The effect of a second porous SiO2 shell in the activity and selectivity of the Fe3O4@SiO2–Pt catalyst in the hydrodenitrogenation of indole is reported. The double Fe3O4@SiO2–Pt@SiO2 structure was prepared by coating Fe3O4 nanoparticles with tetraethyl orthosilicate (TEOS) with a further impregnation of 1.0 wt.% of Pt on the (3-aminopropyl)triethoxysilane functionalized Fe3O4@SiO2 structures. The second porous SiO2 shell, obtained by using a hexadecyltrimethylammonium bromide (CTAB) template, covered the Fe3O4@SiO2–Pt catalyst with a well-defined and narrow pore-sized distribution. The full characterization by TEM, inductively coupled plasma-optical emission spectroscopy (ICP-OES), XRD, and N2 adsorption isotherm at 77 K and vibrating sample magnetometry (VSM) of the catalysts indicates homogeneous core@shell structures with a controlled nano-size of metallic Pt. A significant effect of the double SiO2 shell in the catalytic performance was demonstrated by both a higher activity to eliminate the nitrogen atom of the indole molecule present in model liquid fuel and the improvement of the catalytic stability reaching four consecutive reaction cycles with only a slight conversion level decrease.
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Yu, Linke, and Fengyu Li. "Pt2 Dimer Anchored Vertically in Defective BN Monolayer as an Efficient Catalyst for N2 Reduction: A DFT Study." Catalysts 12, no. 11 (November 8, 2022): 1387. http://dx.doi.org/10.3390/catal12111387.
Повний текст джерелаАнотація:
The electrochemical nitrogen reduction reaction (NRR) using clean energy is considered a promising alternative to the conventional Haber–Bosch process; however, developing a highly active electrocatalyst is still a great challenge. In this study, ten metal dimers anchored in a defective boron nitride (BN) monolayer as double-atom catalysts (DACs) with reverse sandwich structures were screened for their stability and catalytic activity towards NRR by density functional theory (DFT) calculations. Among them, three DACs (Rh2⊥vb-BN, Pt2⊥vb-BN and Rh2⊥vn-BN) were confirmed to be stable and have high promise as NRR electrocatalysts, and Pt2⊥vb-BN particularly distinguishes itself due to its very low limiting potential (−0.06 V). In addition, the electrocatalytic performance of all three DACs prevailed over that of their single-atom catalyst counterparts. We believe that the unique conformation of the reverse sandwich structure has impressive potential for the development of DACs, and we hope that our study provides a new design strategy for DACs for NRR and beyond.
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Cheng, Yu-Wei, Tar-Hwa Hsieh, Yu-Chang Huang, Po-Hao Tseng, Yen-Zen Wang, Ko-Shan Ho, and Yue-Jie Huang. "Calcined Co(II)-Chelated Polyazomethine as Cathode Catalyst of Anion Exchange Membrane Fuel Cells." Polymers 14, no. 9 (April 27, 2022): 1784. http://dx.doi.org/10.3390/polym14091784.
Повний текст джерелаАнотація:
Polyazomethine (PAM) prepared from the polycondensation between p-phenylene diamine (PDA) and p-terephthalaldehyde (PTAl) via Schiff reaction can physically crosslink (complex) with Co ions. Co-complexed PAM (Co-PAM) in the form of gel is calcined to become a Co, N-co-doped carbonaceous matrix (Co-N-C), acting as cathode catalyst of an anion exchange membrane fuel cell (AEMFC). The obtained Co-N-C catalyst demonstrates a single-atom structure with active Co centers seen under the high-resolution transmission electron microscopy (HRTEM). The Co-N-C catalysts are also characterized by XRD, SEM, TEM, XPS, BET, and Raman spectroscopy. The Co-N-C catalysts demonstrate oxygen reduction reaction (ORR) activity in the KOH(aq) by expressing an onset potential of 1.19–1.37 V vs. RHE, a half wave potential of 0.70–0.92 V, a Tafel slope of 61–89 mV/dec., and number of exchange electrons of 2.48–3.79. Significant ORR peaks appear in the current–voltage (CV) polarization curves for the Co-N-C catalysts that experience two-stage calcination higher than 900 °C, followed by double acid leaching (CoNC-1000A-900A). The reduction current of CoNC-1000A-900A is comparable to that of commercial Pt-implanted carbon (Pt/C), and the max power density of the single cell using CoNC-1000A-900A as cathode catalyst reaches 275 mW cm−2.
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Khlebnikov, Alexander, Vladimir Bodunov, Ekaterina Galenko, Alexey Galenko, and Mikhail Novikov. "Synthesis of Substituted Indole-3-carboxylates by Iron(II)-Catalyzed Domino Isomerization of 3-Alkyl/aryl-4-aryl-5-methoxyisoxazoles." Synthesis 50, no. 14 (May 29, 2018): 2784–98. http://dx.doi.org/10.1055/s-0036-1591576.
Повний текст джерелаАнотація:
The iron(II)-catalyzed domino isomerization of 3-alkyl/aryl-4-arylisoxazoles provides a selective access to a wide range of structurally diverse highly substituted indole-3-carboxylates. The operational simplicity, high atom efficiency, and the use of stable starting materials and an inexpensive and low-toxicity catalyst are some of the attractive features of this tandem double ring-opening–ring-closure strategy.
Дисертації з теми "Double Atom Catalyst"
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Richard, Mélissandre. "Application de la technique d'échange isotopique à l'étude de systèmes catalytiques innovants : activation et mobilité d'O2 sur YSZ au sein d’un double-lit et réactivité de l’azote dans les matériaux nitrures pour la catalyse hétérogène." Thesis, Poitiers, 2015. http://www.theses.fr/2015POIT2293/document.
Повний текст джерелаАнотація:
Ce travail porte sur l’étude de systèmes catalytiques innovants par la technique d’échange isotopique (EI) permettant d’apprécier des propriétés fondamentales (activation des molécules en surface, mobilité et réactivité des atomes de réseau) pour comprendre les mécanismes de réaction mis en jeu en catalyse hétérogène et développer des systèmes plus performants. Aussi, l’identification d’espèces adsorbées intermédiaires est possible en couplant la spectrométrie de masse (analyse de la phase gaz) à l’observation de la surface catalytique par spectroscopie DRIFT.L’EI 16O/18O montre des effets de dispersion ou de synergie de LaMnO3 (LM) supportée sur YSZ ou TiO2 expliquant les performances de cette structure pérovskite pour l’oxydation catalytique de C7H8 via un mécanisme suprafacial. L’activité en EI C16O2/C18O2 démontre la mobilité exceptionnelle des atomes O de réseau de YSZ dès 150 °C via la formation d’espèces (hydrogéno)carbonates en surface. En catalyse d’oxydation, à T < 800 °C, cette mobilité est pourtant limitée par l’activation d’O2 à la surface de YSZ. La solution proposée ici est la génération préalable d’une espèce oxygène réactive sur un lit de matériau réductible type LM. Le double-lit LM-YSZ montre d’excellentes performances pour abaisser la température d’oxydation de CH4 à 425 °C via un mécanisme Mars van Krevelen (MvK) où les atomes O de YSZ participent à la réaction par l’intermédiaire d’espèces formiates.L’EI 14N/15N est également utilisé dans ce travail pour analyser la réactivité des atomes N de réseau dans les nitrures métalliques. En particulier, Co3Mo3N et Ni2Mo3N montrent des propriétés remarquables, dépendant de la méthode de préparation ou du prétraitement appliqué. Leur comportement suggère la participation des atomes N dans la réaction de synthèse de NH3 sur le principe d’un mécanisme MvKThis work concerns the study of new catalytic systems by isotopic exchange (IE) technique allowing to appreciate basic properties (molecules surface activation, mobility and reactivity of lattice atoms) to better understand catalytic mechanisms and to develop efficient catalysts. The identification of intermediate adsorbed species is possible by coupling mass spectrometry (gas-phase analysis) with the catalytic surface analysis by DRIFT spectroscopy.IE 16O/18O shows dispersal and synergetic effect of supported LaMnO3 perovskite (LM) on YSZ or TiO2 which explain catalytic performances of this perovskite structure for toluene oxidation via a suprafacial mechanism. IE C16O2/C18O2 activity demonstrates the remarkable lattice O atoms mobility of YSZ from 150 °C via adsorbed (hydrogeno)carbonates. To the contrary, in oxidation catalysis, under 800 °C, this mobility is very limited by O2 activation on YSZ surface. The solution proposed in this work is the previous generation of reactive oxygen species on a first catalytic bed of reducible material as LM. LM+YSZ dual-bed shows very efficient activity to reduce methane oxidation temperature at 425 °C via a Mars-van Krevelen (MvK) mechanism in which lattice O atoms of YSZ take part in the reaction by intermediate formate species.IE 14N/15N is thereafter used to analyse lattice N atoms reactivity of metal nitrides materials. In particular, Co3Mo3N and Ni2Mo3N show interesting properties depending on preparation or pre-treatement routes. This behaviour supposes that ammonia synthesis reaction could be procced via MvK type mechanism with the participation of lattice N of this nitrides
Частини книг з теми "Double Atom Catalyst"
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R., Deeksha, and Deepak Kumar. "Design of Supported Catalysts for Nitrogen Reduction Reaction: A Continuous Challenge." In Advanced Materials and Nano Systems: Theory and Experiment (Part-1), 66–91. BENTHAM SCIENCE PUBLISHERS, 2022. http://dx.doi.org/10.2174/9789815050745122010007.
Повний текст джерелаАнотація:
The production of ammonia is facilitated by the nitrogen reduction reaction (NRR), where the inert di-nitrogen molecule is converted to ammonia. Along with being a major carrier of hydrogen, ammonia holds authority in the fertilizer realm. Therefore, it is inevitable to develop a viable and eco-friendly method of production that is cost-effective and resource-efficient. The primary challenge of nitrogen reduction is the cleavage of the particularly stable nitrogen bond. The most popular Haber-Bosch process for ammonia production, although efficient, is highly energy-intensive, and the need for maintaining exceptionally high temperature and pressure conditions is an environmental concern. As an alternative, the direct conversion of nitrogen has been carried out by photocatalysis and electrocatalysis. However, this strategy falls short of achieving superior conversion efficiencies. Consequently, it is conceivable that a fitting catalyst can be the solution for the difficulties associated with NRR. Over the years, several attempts have been made at formulating the best catalyst, including chromium oxynitride nanoparticles, niobium dioxide, various metal (Ru, Al, Rh, Ga) clusters, single-atom catalysts supported on different surfaces, and double atom catalysts. Recently, perovskites have emerged into the spotlight as excellent catalysts for NRR. In this chapter, we discuss the challenges faced by researchers to formulate righteous catalysts for the sustainable reduction of nitrogen by studying each of these types with a few examples. We also review the recent advancements in the experimental domain of NRR using different electrochemical cells.
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Nawaz Shariff, Shakeel, Supriya Saravu, and Dileep Ramakrishna. "Schiff Base Complexes for Catalytic Application." In Schiff Base in Organic, Inorganic and Physical Chemistry [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.107904.
Повний текст джерелаАнотація:
Primary amines are combined with an aldehyde group to generate Schiff base compounds, which are called condensation imine products. This class of compounds has a general structure, R-C=NR\', where R and R\' represent alkyl/aryl/cyclohexyl/heterocyclic group. These compounds contain an azomethine group that is basic in nature due to, (i) the presence of lone pair of electrons on the nitrogen and (ii) electron-donating nature of the double bond. Hence, these compounds, as ligands, participate in the formation of metal complexes. The presence of lone pair of electrons on the nitrogen atom and the hybridization involved explains the physical, chemical, and spectral properties of nitrogen-containing moieties. In the case of (sp2) hybridization (trigonal structure), the lone pair of electrons occupies either a symmetrical unhybridized 2p orbital that is perpendicular to the plane of trigonal hybrids or a symmetrical hybrid orbital, whose axis is in the plane, leaving behind only the π-electrons in the unhybridized 2p orbital. A very similar type of hybridization is experienced by the nitrogen atom in the azomethine group. Traditional phosphine complexes of nickel, palladium, and platinum, particularly those of palladium, have played an extremely important role in the development of homogeneous catalysis. Schiff base complexes as catalysts have been studied for various organic transformations such as oxidation, epoxidation, reduction, coupling reactions, polymerization reactions, hydroformylations, and many more.
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Cheng, Z., M. Li, and Z. Lu. "2.2 Cobalt- and Iron-Catalyzed Hydrosilylation." In Base-Metal Catalysis 2. Stuttgart: Georg Thieme Verlag KG, 2023. http://dx.doi.org/10.1055/sos-sd-239-00077.
Повний текст джерелаАнотація:
AbstractThe hydrosilylation of readily available alkenes and alkynes represents an atom-economic and straightforward method for the preparation of value-added organosilicon compounds. Among various catalysts, those based on earth-abundant metals such as cobalt and iron demonstrate great potential due to their low cost and toxicity, as well as good catalytic performance. This review discusses recent progress in the cobalt- and iron-catalyzed hydrosilylation of alkenes and alkynes, as well as the sequential double hydrosilylation of alkynes, with an emphasis on the synthetic utility of the methods. The reactivity, regioselectivity, and enantioselectivity can be well-controlled by applying suitable ligands.
Тези доповідей конференцій з теми "Double Atom Catalyst"
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Kodama, Tatsuya, Nobuyuki Gokon, Shin-ichi Inuta, Shin-go Yamashita, Tsuyoshi Hatamachi, and Taebeom Seo. "Molten-Salt Tubular Absorber/Reformer (MoSTAR) Project: Metal-Plate-Bridged Double Tube Reactor." In ASME 2009 3rd International Conference on Energy Sustainability collocated with the Heat Transfer and InterPACK09 Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/es2009-90230.
Повний текст джерелаАнотація:
The Molten-Salt Tubular Absorber/Reformer (MoSTAR) Project, which is jointly conducted by Niigata University, Japan, and Inha University, Korea, aims to develop a novel-type of “double-walled” tubular absorbers/reformers with molten-salt thermal storage at high temperature for use in solar natural-gas reforming and solar air receiver, and to demonstrate their performances on sun with a 5-kWt dish-type solar concentrator. The new concept of “double-walled” reactor tubes was proposed for use in a solar reformer by Niigata University, Japan, and involves packing a molten salt in the annular region between the internal catalyst tube and the exterior solar absorber tube of the double reactor tube. In this work, “metal-plate-bridged” double reactor tubes are newly proposed for use in a solar reformer. Two different sized reactor tubes are constructed, and tested on chemical reaction performance for dry reforming of methane during cooling or heat-discharge mode of the reactor tube using an electric furnace. The experimental results obtained under feed gas mixture of CH4/CO2 = 1:3 at a residence time of 0.36 s and at 1 atm showed that the double reactor tube with the heat storage medium Na2CO3 in the annular region successfully sustained a high methane conversion above 90% with about 0.7-kW output power of the reformed gas based on HHV for 40 min of the heat-discharge mode. The application of the new reactor tubes to solar tubular reformers is expected to help realize stable operation of the solar reforming process under fluctuating insolation during a cloud passage.