Tesis sobre el tema "Metal oxide electrocatalyst"
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GUZMAN, MEDINA HILMAR DEL CARMEN. "Electrocatalytic reduction of CO2 to value-added products". Doctoral thesis, Politecnico di Torino, 2021. http://hdl.handle.net/11583/2907030.
Texto completoGu, Yanjuan. "Nanostructure of transition metal and metal oxide for electrocatalysis". Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B37774396.
Texto completoChen, Youjiang. "Fundamental Aspects of Electrocatalysis at Metal and Metal Oxide Electrodes". Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1284390270.
Texto completoBaez, Baez Victor Antonio. "Metal oxide coated electrodes for oxygen reduction". Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241271.
Texto completoChen, Junsheng. "Ternary Metal Oxide/(Oxy)Hydroxide for Efficient Oxygen Evolution Reaction". Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/25536.
Texto completoGu, Yanjuan y 谷艳娟. "Nanostructure of transition metal and metal oxide forelectrocatalysis". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37774396.
Texto completoBateni, Fazel. "Development of Non-precious Metal and Metal Oxide Electrocatalysts for an Alkaline Lignin Electrolysis Process". Ohio University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1562674707447307.
Texto completoTrotochaud, Lena. "Structure-Composition-Activity Relationships in Transition-Metal Oxide and Oxyhydroxide Oxygen-Evolution Electrocatalysts". Thesis, University of Oregon, 2014. http://hdl.handle.net/1794/18312.
Texto completo2015-03-29
Xing, Shihui. "Rational design of bi-transition metal oxide electrocatalysts for hydrogen and oxygen evolutions". Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/209307/1/Shihui_Xing_Thesis.pdf.
Texto completoWu, Ziyang. "Rational design of two-dimensional architectures for efficient electrocatalysis". Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/235888/1/ziyang%2Bwu%2Bthesis%284%29.pdf.
Texto completoThenuwara, Akila Chathuranga. "Investigations of interlayer chemistry in layered metal oxides for energy conversion and storage". Diss., Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/519285.
Texto completoPh.D.
The overall goal of this dissertation research was to design, tailor and understand layered metal oxides in the context of electrocatalytic energy conversion and storage processes. To accomplish this goal the thesis research combined electrochemistry, state-of-the-art structural characterization and theoretical calculations. The hypothesis examined in this dissertation is that incorporation of metal atoms or metal ions into the sheets and/or interlayer region of the layered materials will enhance the properties of selected 2D materials for chemistry relevant to electrochemical energy conversion (i.e. electrochemical water splitting catalysis; H2O ® H2 + 1/2O2) and energy storage (i.e., as pseudocapacitors). The primary 2D layered materials investigated in this thesis research were birnessite (nominally MnO2) and Fe:Ni double hydroxide materials. Metals (cations) used to modify the geometric and electronic structure of the layered materials include Cu, Ni, and Co. Perhaps the result with broadest impact to result from the integration of experimental and theoretical studies in the thesis research was that the confinement of solvated redox active metals within the interlayer region of 2D layered materials can be used to facilitate their electron transfer reaction rates (relative to the respective unconfined metal) and energy related electrochemistry. This new paradigm for electron transfer has implications for the development of novel electrocatalytic materials for energy conversion. Research showed that the electrocatalytic activity of birnessite toward water oxidation (2H2O® 4H+ + 4e- + O2) was increased by intercalating zero valent copper into the interlayer region of the layered manganese oxide. Electrocatalytic studies showed that the Cu-modified birnessite exhibited an overpotential for water oxidation of ∼490 mV (at a current density of 10 mA cm 2) and a Tafel slope of 126 mV/decade compared to ∼700 mV (at 10 mA cm-2) and 240 mV/decade, respectively, for birnessite without copper. Impedance spectroscopy results suggested that the charge transfer resistivity of the Cu-modified sample was significantly lower than Cu-free birnessite, suggesting that Cu in the interlayer increased the conductivity of birnessite leading to an enhancement of water oxidation kinetics. It was experimentally shown that the oxygen evolution reaction (OER; water oxidation) catalysis of redox active transition metal ions (Ni2+ and Co2+) can be enhanced by individually confining them in the interlayer region of birnessite. It was demonstrated that the metal confined electrocatalyst reached a current density of 10 mA cm−2 at much lower overpotentials than pure Ni and Co oxides, and pristine birnessite. For example, with interlayer nickel and cobalt, overpotentials of 400 and 360 mV, respectively, were achieved for the OER. Molecular dynamics (MD) simulations suggested that electron transfer reaction rates relevant to OER and involving Ni or Co were enhanced when the metal cations were confined in the interlayer of birnessite. The strategy of metal confinement, which was successfully applied to layered manganese oxide to improve OER activity was extended to Ni-Fe based layered double hydroxide. It was demonstrated that the electrocatalytic activity of NiFe layered double hydroxides (NiFe LDHs) for the OER could be significantly enhanced by systematic cobalt incorporation using coprecipitation and/or intercalation. Electrochemical measurements showed that cobalt modified NiFe LDH possessed an enhanced activity for the OER relative to pristine NiFe LDH. The cobalt doped NiFe LDH exhibited overpotentials in the range of 290−322 mV (at 10 mA cm−2), depending on the degree of cobalt content. The cobalt intercalated NiFe LDH achieved a current density of 10 mA cm−2 at a much lower overpotential of ∼265 mV (compared to 310 mV for NiFe LDH). With regard to energy storage, it was shown that the pseudocapacitive charge storage in layered manganese oxide was a sensitive function of interlayer composition and distance. Even though pristine layered manganese oxide shows a 7 Å interlayer spacing, the interlayer engineering via metal (Mg2+) intercalation and thermal annealing led to layered manganese oxide materials with variable interlayer spacings of 10 and 5.6 Å respectively. The interlayer expanded layered manganese oxide (10 Å interlayer spacing) exhibited an improved specific capacitance of 380 Fg-1, in comparison to synthetic Na-birnessite (specific capacitance of 200 F g-1). Dehydrated Na-birnessite (~5.6 Å spacing) produced by annealing to expel interlayer water, showed the lowest specific capacitance of 50 Fg-1. Experimental results showed that interlayer expanded manganese oxide (with intercalated Mg2+) was unstable if exposed to a solution containing only Na+ cation electrolyte. In this circumstance, the interlayer distance decreased from the expanded 10 Å value back to an interlayer distance of 7 Å and a specific capacitance of ~200 F g-1; values associated with synthetic Na-birnessite. Finally, a highly active alkaline medium hydrogen evolving electrocatalyst based on earth abundant materials (Co, Mo and P) was developed and the catalyst exhibited a ~0 V onset for the hydrogen evolution reaction (HER; 2H+ + 2e- ® H2). This value was comparable to that of the precious metal platinum. The Co-Mo-P catalyst was prepared by room temperature electrodeposition and it exhibited an overpotential of ~ 25-30 mV for HER at a geometrical current density of 10 mA cm-2 in an alkaline medium. A DFT theoretical investigation revealed that a Co-Mo center acts as the water-dissociation site enhancing the alkaline medium HER.
Temple University--Theses
Fugate, Elizabeth Anne. "Investigation of Electronic Structure Effects of Transition Metal Oxides toward Water Oxidation and CO2 Reduction Catalysis". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1462868623.
Texto completoSayeed, Md Abu. "Electrochemical fabrication of nanostructured metal oxides for the oxygen evolution reaction". Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/116769/1/Md%20Abu_Sayeed_Thesis.pdf.
Texto completoEnman, Lisa. "Structure-Property Relationships in Mixed-Metal Oxides and (Oxy)Hydroxides for Energy Applications". Thesis, University of Oregon, 2019. http://hdl.handle.net/1794/24227.
Texto completo2020-01-11
Perera, Reshani H. "Nitric Oxide Synthase in Confined Environments: Detection and Quantification of Nitric Oxide Released From Cells and Modified Liposomes Using a Sensitive Metal Catalyst-PEDOT Modified Carbon Fiber Electrode". Cleveland State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=csu1297142093.
Texto completoWatzele, Sebastian Anselm [Verfasser], Aliaksandr S. [Akademischer Betreuer] Bandarenka, Ifan E. L. [Gutachter] Stephens y Aliaksandr S. [Gutachter] Bandarenka. "Methodological Aspects of In-Depth Electrochemical Characterization of Metal and Metal Oxide Electrocatalysts / Sebastian Anselm Watzele ; Gutachter: Ifan E. L. Stephens, Aliaksandr S. Bandarenka ; Betreuer: Aliaksandr S. Bandarenka". München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1206337753/34.
Texto completoXue, Song [Verfasser], Aliaksandr S. [Akademischer Betreuer] Bandarenka, Egill [Gutachter] Skulason y Aliaksandr S. [Gutachter] Bandarenka. "The role of electrolyte composition in the activity and selectivity of metal and metal oxide electrocatalysts / Song Xue ; Gutachter: Egill Skulason, Aliaksandr S. Bandarenka ; Betreuer: Aliaksandr S. Bandarenka". München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1204200289/34.
Texto completoColombo, A. "PREPARATION AND PERFORMANCE EVALUATION OF MATERIALS FOR ELECTROCATALYTIC APPLICATIONS". Doctoral thesis, Università degli Studi di Milano, 2010. http://hdl.handle.net/2434/150125.
Texto completoNaidoo, Qiling Ying. "Multicomponent catalysts for methanol electro-oxidation processes synthesized using organometallic chemical vapourde position technique". Thesis, University of the Western Cape, 2011. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_7491_1320654024.
Texto completoHammouche, Abderrezak. "Contribution à l'étude de La(1-x)Sr(x)MnO3 comme matériau d'électrode à oxygène à haute température". Grenoble INPG, 1989. http://www.theses.fr/1989INPG0075.
Texto completoFavaro, Marco. "A rational approach to the optimization of efficient electrocatalysts for the next generation Fuel Cells". Doctoral thesis, Università degli studi di Padova, 2014. http://hdl.handle.net/11577/3424667.
Texto completoIl progetto di dottorato nasce all’interno del gruppo di ricerca di Superfici e Catalizzatori operante nel dipartimento di Scienze Chimiche, nell’ambito della borsa a titolo vincolato “Un approccio razionale alla ottimizzazione di elettrocatalizzatori efficienti per le celle a combustibile di nuova generazione”, finanziata da fondazione CARIPARO. Le tematica è stata focalizzata sulla preparazione e caratterizzazione di nuovi materiali a base di carbonio utilizzabili per applicazioni in celle a combustibile di tipo PEMFCs (Polymer Electrolyte Membrane Fuel Cells) ad ossigeno-idrogeno. La preparazione dei materiali è avvenuta facendo uso di differenti tecniche, in relazione al tipo di materiale oggetto di studio ed alle applicazioni che tali materiali possono offrire. Con riferimento allo studio dei sistemi modello (grafite pirolitica altamente orientata, HOPG, e carbonio vetroso, GC), il drogaggio degli stessi mediante l’introduzione di eteroatomi (in particolare azoto) è avvenuto ricorrendo alla tecnica dell’impiantazione ionica, mentre lo studio di nuove funzionalità chimiche è stato permesso dall’utilizzo di tecniche di Wet Chemistry, in particolare mutuate dalla sintesi elettrochimica. La deposizione di film sottili o di nanoparticelle (metalliche o a base di ossidi di metalli di transizione) su tali materiali modificati è stata effettuata facendo uso di tecniche avanzate come la deposizione fisica da fase vapore (PVD) in condizioni controllate di Ultra Alto Vuoto (UHV), in grado di offrire un controllo su scala atomica della deposizione di tali film. Sono state utilizzate anche tecniche di deposizione tradizionali quali la riduzione chimica o elettrochimica di opportuni precursori metallici: l‘utilizzazione di una siffatta combinazione sinergica tra tali differenti tecniche di preparazione ha permesso di ottenere materiali caratterizzati da strutture e proprietà peculiari. La caratterizzazione di tali materiali è svolta utilizzando le facilities del gruppo di Scienza delle Superfici, come la spettroscopia di fotoelettroni (XPS) o della banda di valenza (UPS), la microscopia ad effetto tunnel o a forza atomica (STM - AFM), la microscopia elettronica e la dispersione energetica dei raggi X indotta dagli elettroni (SEM-EDX), la diffrazione di elettroni lenti (LEED). Allo scopo di caratterizzare maggiormente in dettaglio la struttura e le proprietà chimiche dei materiali preparati sono state usate estensivamente le tecniche di indagine offerte dalla luce di sincrotrone (HR-XPS, NEXAFS, ARPES, ResPES, PEEM), mentre lo studio della reattività catalitica si basa su tecniche derivate dall’analisi elettrochimica, in particolare la voltammetria ciclica ed a scansione lineare del potenziale applicato, nonchè tecniche elettro-dinamiche come la voltammetria su elettrodo rotante. Infine, allo scopo di supportare i dati sperimentali o portare la comprensione delle proprietà dei materiali ad un livello più profondo, simulazioni mediante teoria del funzionale densità (DFT) sono state adottate per un approccio critico allo studio dei materiali preparati (in collaborazione con il gruppo coordinato dalla prof. Cristiana Di Valentin, Università di Milano Bicocca). Durante il corso del dottorato, diverse collaborazioni sono state perseguite con gruppi interni al Dipartimento di Scienze Chimiche o anche Esteri, come l’unità di ricerca “Interfaces and Energy Conversion E19”, dell’università tecnica di Monaco di Baviera (TUM, Technische Universität München, Germania), coordinata dai proff. O. Schneider e J. Kunze-Liebhäuser.
Jain, Deeksha. "Development of Alternative Materials to Replace Precious Metals in Sustainable Catalytic Technologies". The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1566176607919202.
Texto completoQueiroz, Adriana Coêlho. "Síntese e estudo da atividade eletrocatalítica de óxidos de metais de transição e de nanopartículas de prata e ouro para a reação de redução de oxigênio". Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/75/75131/tde-25102011-170304/.
Texto completoThe oxygen reduction reaction (ORR) was studied on electrocatalysts composed by pure and mixed transition metal oxides of Mn, Co, and Ni, including spinel-like structures, and by Ag, Au, and Ag3M/C (M= Au, Pt, Pd e Cu) bimetallic nanoparticles, in alkaline electrolyte. The transition metal oxides were synthesized by thermal decomposition of their nitrates, and the silver and gold-based nanoparticles by chemical reduction using borohydride. The electrocatalysts were characterized by X-Ray Diffraction and X-Ray Absorption Spectroscopy (in the case of the metal oxides). The manganese-based oxide materials showed high activity for the ORR, in which the in situ spectroscopic results evidenced the Mn(IV) to Mn(III) reduction, in the range of the ORR onset. In this case, the electrocatalytic activities were correlated to the transfer of electron from Mn(III) to O2. However, they presented strong deactivation after several potentiodynamic cycles, which was ascribed to the formation of the electrochemically inactive phase of Mn3O4, as indicated by the XRD results, after the electrochemical experiments. On the other hand, the MnCo2O4 spinel-like material showed high activity and stability for the ORR. Its high electocatalytic activity was attributed to the CoII/CoIII redox pair, taking place at higher potentials, in relation to that of the CoOx e MnOx pure phases, due to the Co and Mn interactions in the spinel lattice. Contrarily to the behavior observed for the manganese-based materials, the spinel oxide presented high stability, which was ascribed to the non alteration of its crystallographic structure in the range of potentials tha the ORR takes place. For the Au and Ag-based materials, the electrochemical experiments indicated higher electrocatalytic activities for Ag3Au/C. In this case, its higher activity as associated to two main aspects: (i) to a synergetic effect, in which the gold atoms act in the activation region, facilitating the hydrogen addition, and the neighboring Ag atoms promoting the O-O bond breaking, leading the ORR to the 4-electrons pathway; (ii) to the increased Ag-O bond strength, due to the electronic interaction between Ag and the Au atoms, resulting in a faster O-O bond breaking, enhancing the electrocatalytic activity of the Ag atoms in the Ag3Au/C nanoparticle, in relation to that on the pure Ag. Therefore, the ORR presented lower overpotential and higher number of electrons in the Ag3Au/C electrocatalyst, when compared to the other investigated bimetallic nanoparticles.
ANTONIASSI, RODOLFO M. "Preparação de nanopartículas de platina com diferentes morfologias nos materiais Pt/C e PtSnO2/C para aplicação como ânodo em células a combústível de etanol direto". reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/28036.
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Neste trabalho foi estudado o efeito da adição de íons haletos (Cl-, Br- e I-) sobre a morfologia das nanopartículas de Pt na produção de catalisadores de Pt/C e PtSnO2/C. Foi desenvolvida uma metodologia de síntese simples capaz de produzir nanopartículas de Pt predominantemente cúbicas com orientação preferencial Pt(100), diretamente suportadas em carbono sem o uso de agentes estabilizantes. Brometo de potássio foi utilizado como agente direcionador de superfície para obtenção do material preferencialmente orientado. O controle de adição do precursor de Pt e de KBr foi crucial para obter nanocubos de Pt de 8 nm bem dispersos sobre o suporte. Na preparação dos catalisadores de PtSnO2/C, o processo de adição do SnCl2 também foi decisivo na obtenção das nanopartículas de Pt com tamanho e morfologia de interesse. Nanocubos de Pt coexistindo com SnO2 disperso foram exclusivamente obtidos ao adicionar o SnCl2 na etapa final da síntese, quando as nanopartículas cúbicas de Pt já estavam formadas. Enriquecidos de domínios Pt(100), os materiais em forma cúbica de Pt/C e PtSnO2/C se mostraram menos afetados pelo acúmulo dos intermediários indesejados provenientes da reação de eletro-oxidação de etanol e foram mais tolerantes ao envenenamento por monóxido de carbono. Resultados similares foram observados para a oxidação de CO e metanol, utilizados como apoio para compreensão da eletro-oxidação de etanol. O efeito morfológico destes materiais no desempenho elétrico em célula a combustível de etanol direto foi avaliado. Pt/C e PtSnO2/C contendo nanopartículas de Pt com orientação preferencial Pt(100) forneceram maiores valores de densidade de potência e de seletividade para CO2 comparados aos catalisadores de Pt/C e PtSnO2/C com nanopartículas de Pt sem orientação preferencial.
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
Creazzo, Fabrizio. "Oxygen evolution reaction at cobalt oxides/water interfaces : heterogeneous electrocatalysis by DFT-MD simulations & metadynamics Ab initio molecular dynamics study of an aqueous NaCl solution under an electric field Ionic diffusion and proton transfer in aqueous solutions of alkali metal salts Ionic Diffusion and Proton Transfer in Aqueous Solutions under an Electric Field: State-of-The-Art Ionic diffusion and proton transfer of MgCl2 and CaCl2 aqueous solutions: an ab initio study under electric field DFT-MD of the (110)-Co 3 O 4 cobalt oxide semiconductor in contact with liquid water, preliminary chemical and physical insights into the electrochemical environment Enhanced conductivity of water at the electrified air–water interface: a DFT-MD characterization Ions tune interfacial water structure and modulate hydrophobic interactions at silica surfaces". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASE012.
Texto completoIn this thesis, DFT-MD simulations, coupled with state-of-the-art metadynamics techniques, are applied to gain a global understanding of Co3O4 and CoO(OH) cobalt oxide aqueous interfaces in catalyzing the oxygen evolution reaction (OER), and hence possibly help in the design of novel catalysts basedon non-precious materials, a current key field of research in science and technology, especially of importance for the hydrogen economy, for green technology in a period of time with an ever more growing demand in green-energy. In this thesis, we step-by-step reveal the OER mechanisms on spinel Co3O4 andCoO(OH) cobalt aqueous electrocatalysts carefully and rationally via novelmetadynamics techniques.Up to now, the literature has never taken into account the atomistic modifications on the electrode structure as well as on the interfacial water into their modeling of OER processes. Such lack of knowledge clearly represents a significant hurdle toward the development of improved catalysts, which couldbe overcome by employing methods able to track the catalytic features of theOER at the atomistic scale. For the first time, we show how important itis to take into consideration the presence of the liquid water environment inthe structural characterization of catalyst surfaces, i.e. for (110)-Co3O4 and(0001)-CoO(OH) in this work. A detailed characterization of chemical andphysical properties of the aqueous interfaces is provided (i.e. structure, dynamics, spectroscopy, electric field), for the (110)-Co3O4 and (0001)-CoO(OH)aqueous surfaces.A study of the OER is presented not only by looking at the catalysts, butalso by addressing the role of the water environment in the catalytic process,not done before in literature. Accordingly, both gas-phase and liquid-phaseOER are here investigated at the (110)-Co3O4 and (0001)-CoO(OH) adoptinga novel enhanced sampling metadynamics approach able to address a widerange of chemical reaction mechanisms and to fully include the role of thesolvent degrees of freedom, allowing to unveil reaction networks of remarkablecomplexity. The energetics, kinetics and thermodynamics behind the OER aretherefore found at these cobalt oxide surfaces
Berglund, Sean Patrick. "Mixed metal oxide semiconductors and electrocatalyst materials for solar energy conversion". 2013. http://hdl.handle.net/2152/22903.
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Tovide, Oluwakemi Omotunde. "Graphenated polyaniline nanocomposite for the determination of polyaromatic hydrocarbons (pahs) in water". 2013. http://hdl.handle.net/11394/3851.
Texto completoThe thesis presents a simple, sensitive, low cost and a novel graphenated polyaniline doped tungsten trioxide nanocomposite, as an electrochemical sensor for the detection and quantitative and determination of PAHs, which are ubiquitous, toxic, as well as dangerous organic pollutant compounds in the environment. The selected PAHs (anthracene, phenanthrene and pyrene) in wastewater were given priority as a result of their threat to human nature and that of the environment. In order for a healthy, non-polluted and well sustainable environment, there is need for an instrument that is capable of detecting and quantifying these organic pollutants onsite and also for constant monitoring. The nanocomposites were developed by chemical and electrochemical methods of preparations, exploiting the intrinsic properties of polyaniline, graphene and tungsten trioxide semiconducting materials. Chemically, graphene-polyaniline (GR-PANI) nanocomposite was synthesised by in situ polymerisation method, then casted on a surface of glassy carbon electrode to form GR-PANI modified electrode. The properties of the prepared electrode were investigated through morphological and spectroscopic techniques, which confirmed the formation of the composite. The electroactivity of the prepared modified electrode revealed great improvement in cyclic and square wave voltammetric response on anthracene. A dynamic range of 2.0 × 10-5 to 1.0 × 10-3 M and detection limit of 4.39 x 10-7 M was established.
黃馨賢. "Screening and characterization of metal oxide electrocatalysts for oxygen evolution reaction". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/dde4xn.
Texto completo逢甲大學
化學工程學系
103
In this study, oxygen evolution catalysts was rapidly screened by scanning electrochemical microscopy (SECM). The Ru and Co oxide based arrays were prepared based on the concept of the combinational method. The element including Ir,V,Fe,Ni,Mo and Mn were used as the binary or ternary metal oxide composition. The surface morphology and elemental composition of metal oxide catalysts were characterized by scanning electron microscope (SEM) and energy dispersive spectrometer (EDX), respectively. Catalyst arrays were screened with SG-TC mode by SECM for oxygen evolution reaction. Linear sweep voltammetry, polarization curves and Tafel curves analyses were used to determine the initial potential, electron transfer coefficient, Tafel slope, and standard rate constant of the catalyst. The results show V1Ru3Co1Ox and V2Ru2Co1Ox catalysts have the better initial potential of 0.42±0.02 V and the larger standard rate constant (k0A) of 1.14×10-5 cm/s.
Thangaraju, Mahadevan. "Study of precious metal-oxide based electrocatalysts for the oxidation of methanol". Thesis, 1996. http://hdl.handle.net/1957/34264.
Texto completoSlanac, Daniel Adam. "Design of nanocomposites for electrocatalysis and energy storage : metal/metal oxide nanoparticles on carbon supports". Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-08-6060.
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Anju, V. G. "Electrocatalysis using Ceramic Nitride and Oxide Nanostructures". Thesis, 2016. http://etd.iisc.ernet.in/handle/2005/2919.
Texto completoTurner, Travis Collin. "Synthesis, characterization, and oxygen evolution reaction catalysis of nickel-rich oxides". Thesis, 2014. http://hdl.handle.net/2152/26198.
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Bayeh, Anteneh Wodaje y Anteneh Wodaje Bayeh. "Advanced Metal Oxide Electrocatalysts Modified Graphite Felt as High-Performance Electrode for Vanadium Redox Flow Batteries". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/2jf9s4.
Texto completo國立臺灣科技大學
材料科學與工程系
107
As one of the most promising electrochemical energy storage systems, vanadium redox flow battery (VRFB) has received increasing attention due to its attractive features for large-scale storage applications. However, high production cost and the relatively low energy efficiency still limit their feasibility. Therefore, developments of powerful electrocatalyst and electrode materials with low cost are critical for the design of VRFB. To improve the energy density and overall performance for large scale applications, extensive research has been carried out on the electrode modification methods for VRFB. First, to increase the electrocatalytic activity of graphite felt (GF) electrodes in vanadium redox flow batteries (VRFBs) toward the VO2+/VO2+ redox couple, we prepared stable, high catalytic activity, and uniformly distributed hexagonal Ta2O5 nanoparticles on the surface of GF by varying the Ta2O5 contents. Scanning electron microscopy (SEM) revealed the amount and distribution uniformity of the electrocatalyst on the surface of GF. It was found that the optimum amount and uniformly immobilized Ta2O5 nanoparticles on GF surface provided the active sites, enhanced hydrophilicity and electrolyte accessibility, thus remarkably improved electrochemical performance of GF. In particular, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results showed that the Ta2O5-GF nanocomposite electrode with weight percentage of Ta2O5 to GF of 0.75 wt% exhibited the best electrochemical activity and reversibility toward the VO2+/VO2+ redox reaction, when compared with the other electrodes. The corresponding energy efficiency was enhanced by ~ 9% at a current density of 80 mA cm−2, as compared with untreated GF. Furthermore, the charge–discharge stability test with 0.75 wt% Ta2O5-GF electrode at 80 mA cm−2 showed that after 50 cycles, there was no obvious attenuation of efficiencies signifying, the best stability of Ta2O5 nanoparticles which strongly adhered on the GF surface. Second, we synthesized simple, inexpensive, and conductive W18O49 nanowires (W18O49NWs) as electrocatalysts on the surface of GF through the one-step solvothermal process. Cyclic voltammetry and electrochemical impedance spectroscopy studies revealed that W18O49NWs exhibit electrocatalytic effects on a VO2+/VO2+ redox couple on the positive side, which enhance the electrochemical kinetics of the redox reactions. To further improve the electrochemical performance of the W18O49NWs, the sample was thermally annealed with a controlled amount of H2/Ar atmosphere to form oxygen-vacancy–rich hydrogen-treated W18O49NWs (H-W18O49NWs). When used as an electrode in a VRFB single cell, this material demonstrated outstanding performance with 9.1% and 12.5% higher energy efficiency than cells assembled with W18O49NWs and treated GF, respectively, at a high current density of 80 mA cm−2. The superior performance of the H-W18O49NW electrocatalyst-based electrode can be attributed to the presence of numerous oxygen vacancies, which were proven to act as active sites for the VO2+/VO2+ redox reaction. Moreover, the uniformly immobilized and 1D nature of the W18O49NWs facilitated the charge-transport process, enhanced hydrophilicity and electrolyte accessibility, and thus remarkably reduced electrochemical polarization during the mass transfer of active species. The long-term cycling performance confirmed the outstanding durability of the as-prepared H-W18O49NWs–based electrode with negligible activity decay after 100 cycles. Third, we use a simple, low-cost, and powerful titanium niobium oxide–reduced graphene oxide (TiNb2O7–rGO) nanocomposite electrocatalyst which was synthesized through dispersion and blending in aqueous solution followed by freeze-drying and annealing for all-vanadium redox flow battery (VRFB). The TiNb2O7 nanoparticles are uniformly anchored between the rGO sheets; simultaneously, the rGO sheets are separated using TiNb2O7 nanoparticles. The synergistic effects between them prevent the agglomeration of the nanoparticles and restacking of the rGO sheets. Cyclic voltammetry and electrochemical impedance spectroscopy results reveal that among all prepared samples, the TiNb2O7–rGO nanocomposite electrocatalyst exhibits the most favorable electrocatalytic activity toward VO2+/VO2+ and V3+/V2+ at the positive electrode and the negative electrode, respectively, to facilitate the electrochemical kinetics of the vanadium redox reactions. The corresponding energy efficiency is improved by ~11.1% and 12.34% at current densities of 80 and 120 mA cm−2, respectively, compared with pristine graphite felt. The superior performance of the TiNb2O7–rGO nanocomposite electrode may have been due to the synergistic effects related to the high electronic conductivity of rGO nanosheets and the interfacial properties created within TiNb2O7 and rGO. Furthermore, the charge-discharge stability test demonstrates the outstanding stability of the TiNb2O7–rGO electrodes. The TiNb2O7–rGO-based VRFB exhibits negligible activity decay after 200 cycles. The remarkable electrocatalytic activity and mechanical stability are achieved due to the TiNb2O7–rGO nanocomposite being strongly anchored on the graphite felt surface for a substantial time during repetitive cycling.
Muthumariappan, Akilarasan y Akilarasan Muthumariappan. "Morphologically Tuned Transition Metal Oxide as a High Surface Electrocatalysts for Electrochemical (Bio) Sensors and Supercapacitor Applications". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/h2963c.
Texto completo國立臺北科技大學
能源與光電材料專班(EOMP)
107
The Transition Metal Oxides (TMO) clenches a vast perspective for the expansion of various novel materials with its prospective in medical, energy storage, electrochemical sensor and biosensor applications. However, as the electrode materials, the fabrication of nano-scaled TMO have some theoretical limitations, it can be resolved by current synthesis known protocols and also the carbon (graphite, graphene, reduced graphene oxide, and carbon nanotubes) based matrix were combined with metal oxide to enhance their properties. Nevertheless facilely, tuning the morphology of TMO results in the enhancement of catalytic activity, conductivity, and physical and chemical properties. Nowadays, domestic waste, is an extensive problem in all over the nation. Due to lack of proper maintenance, awareness, and proper disposal systems, the problem is rather more acute in developing nations. When this waste entered into the landfill, it will be hazardous to the environment and cause health risks to human. On the other hand, these waste are considered as a valuable one, because it consists of a massive amount of iv metals, including precious metals. Therefore, the recovery of metals such as gold, silver, tantalum, aluminum, and Iron from waste become an emerging trend. An extensively utilized active component of a glucose sensor, cuprous oxide (Cu2O) is synthesized and dealt with various annealing temperatures at 400, 600, and 800◦C. The impacts of annealing temperatures on morphology, electro-active surface area, and the glucose sensing properties of cuprous oxides are investigated and spotted that, 600◦C is an effective annealing temperature. Then, a comprehensively applied effective material of the dopamine (DA) and uric acid (UA) sensors, Zinc oxide (ZnO) is prepared through the microwave method with the different stoichiometric ratios of urea, such as [C4H6O4Zn ·2H2O: CH4N2O]=[1:1], [1:2], and [1:3], respectively. After that, the DA and UA biosensor over the cost-effective screen-printed carbon electrode (SPCE) adaption method. The functional (mono and binary) microstructures of transition metal oxides (Co and Mn) with different morphologies have been prepared through simple one-step hydrothermal methodology. The (mono and binary) microstructures of transition metal oxides (Co and Mn) such as Co3O4 polyhedrons (PHs), Mn3O4 microcubes (MCs), MnCo2O4 microflowers (MFs) and CoMn2O4 hollow microspheres (HMs) were employed for the specific and sensitive detection of triptan drug Rizatriptan benzoate (RZB), to evaluate the electrocatalytic ability of transition metal oxides towards electrochemical biosensing. Finally, aluminium oxide nanoparticles (Al2O3 NPs) has recovered through a facile one-step sonochemical methodology. The as-recovered Al2O3 NPs were employed for the specific and sensitive detection of omeprazole (OMZ), which comes under the class of protonpump inhibitor. Furthermore, the recovered material was employed as an active participant in supercapacitor application, which exhibited an appreciable specific capacitance value (688 F/g) at 1 A/g current density in 1 M KOH and maintained 86 % capacitance retention even after 3000 GCD cycles.
Chiou, Yuh-Jing y 邱郁菁. "Electrocatalysis Applications of Palladium and Gold Catalysts Supported on Metal Oxide Modified Multi-Walled Carbon Nanotubes". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/00347803783944807580.
Texto completo大同大學
材料工程學系(所)
99
For the application of direct formic acid fuel cell, Pd catalyst with some modification attracts the study attention for its electrocatalytic advantages. To benefit the catalytic performance and prevent the catalyst poison problem, this study develops Pd basis catalysts, which have solid solution phase with Au and ceria/ceria-zirconia modified MWCNTs substrate, by impregnation and polyol methods. The composition, structure and morphology are analyzed by ICP, XRD and FETEM, respectively. For Au-Pd bimetal catalysts, the formation of solid solution phase and the compositions of the catalysts are proved to be consistent with the initial designation. For MWCNTs modified by ceria or ceria-zirconia, both mesoporous structure of ceria/ceria-zirconia and the advanced breaking of MWCNTs in the impregnation process may cause the surface area increasing of MWCNTs. Zr doping may decrease the temperature of lattice oxygen desorption. The addition of metal can fill the defect of the substrate and decrease the surface area. Pd is the main dominant to promote the reaction and lower the reaction temperature in the TPD helium process. In electrocatalysis, Au-Pd solid solution can prevent the leaching of Pd in formic acid, while the oxide modified support can prevent catalyst poison. The prepared catalysts can totally convert CO between 150~250oC. More Pd can convert 100% CO at lower temperature. It can be considered that, both the formation of solid solution, Au-Pd, and the oxide modification of MWCNTs can decrease the activation energy of the catalyzing reaction and have better catalytic performance.
Chin, Chih-Chun y 金智駿. "Preparation of Mesoporous Metal Oxide Composites as Electrocatalysts by Soft Template Method for Cathode Material of Lithium-Air Batteries". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/31888056569858071372.
Texto completo國立高雄大學
應用化學系碩士班
103
Oxygen reduction reactions ( ORR ) at the air cathode in non-aqueous electrolytes are well-known to influence the performance of Li-air batteries. In this work, highly ordered mesoporous metal oxide composites were designed as electrocatalysts and porous air cathode material in the Li-air battery. The highly ordered mesoporous MnO2/C and TiO2/C composites were synthesized by soft template method and hydrothermal method, combining solvent-evaporation-induced self-assembly and the in situ carbothermal reduction reaction and using the triblock copolymer F127 as the structure-directing agent and resol as the carbon source. In summary, the XRD patterns show metal oxide can be attributed to a pure and well-crystallized MnO2 and TiO2 phase. The metal oxide composites with large specific surface area 424 m2/g ( MnO2/C ) and 599 m2/g ( TiO2/C ). The porous structure of metal oxide composites provides high electrocatalytic active sites and sufficient transmission paths for O2 and electrolyte. Both ordered metal oxide composites show good elecrcatalytic activity toward Oxygen Reduction Reactions ( ORR ) / Oxygen Evolution Reactions ( OER ) in non-aqueous electrolytes. Employing the ordered mesoporous metal oxides as electrocatalyst in Li-air batteries, the Li-air batteries display lower overpotential and good discharge capacity. This result demonstrates ordered mesoporous metal oxide composites are promising cathode electrocatalysts for non-aqueous Li-air batteries.
Guo, Mann-Charn y 郭蔓嬋. "Adding metal oxides in Pt anode electrocatalysts for enhancing CO tolerance in proton exchange membrane fuel cells". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/81445252234693930210.
Texto completo國立中興大學
環境工程學系所
100
The aim of this study is to discuss the preparation of the membrane-electrode assembly (MEA) by using carbon nanotubes (CNTs) in proton exchange membrane fuel cell (PEMFC). Different pretreatment procedures of carbon supports are also considered to evaluate the catalytic activity with various catalysts. Besides, the addition of metal oxides such as CeO2、ZrO2 and SnO2 are investigated to enhance the electrocatalytic activity and the tolerance of different CO concentrations. All catalysts are characterized by means of FESEM, TEM, XRD, BET and ESCA. The experimental results show that the effects of various preparation methods on the MEA to determine the best operating parameters. The 240 seconds hot-press with temperature is 135 oC has been selected for further experiments. Additionally, the investigation of the catalytic activity compared with different pretreatment procedures for catalyst support indicates that CNTs pretreated with nitric acid at 50 oC for two days (CNTs-50 oC-2d) that are supported active metals has higher catalytic activity than others. It is supposed that CNTs-50oC-2d supports have higher surface area provided more active sites and the gas molecules may easily diffuse into the pores to be reacted. Moreover, the electrocatalytic activities by using several catalysts included 5%SnO2-5%Pt/C, 5%ZrO2-5%Pt/C at the same voltage are higher than those without adding any MOx, and 5%SnO2-5%Pt/C is the effectiveness catalyst found after testing .On the other hand, it was reported that the CO tolerance of electrocatalyst was also enhanced by the addition of SnO2 and ZrO2 under the CO concentration is 100 ppm. The CO tolerance are in the following order as 5%ZrO2-5%Pt/C > 5%SnO2-5%Pt/C > 5%Pt/C > 5%CeO2-5%Pt/C. The effect of various concentrations of CO (0、50 and 100 ppm) shows that 5%ZrO2-5%Pt/C catalyst displays a better CO tolerance than the others. Consequently, the electrocatalytic activity and CO tolerance of catalysts are both enhanced while MOx added with Pt.
Alves, Ana Catarina Gomes Moreira. "Synthesis and characterization of abiotic electrocatalysts based on reduced graphene oxide for oxygen reduction reaction". Master's thesis, 2019. http://hdl.handle.net/10451/40629.
Texto completoThe use of low-temperature fuel cells as power supplies of energy conversion devices is attracting considerable interest because of the direct electrochemical conversion of a fuel, e.g. hydrogen and glucose, and an oxidant, such as oxygen, producing electrical current. The sluggish kinetic of the oxygen reduction reaction (ORR) on the cathode half-reaction is particularly investigated since its acceleration relies on the development of efficient electrocatalysts. Unfortunately, the most promising catalysts for ORR are platinum-based materials that exhibit poor durability, limited resource and high cost. Under such circumstances, the development of non-noble, efficient and low-cost electrocatalysts has attracted a great deal of attention. The present dissertation focuses on the synthesis and physicochemical characterization of graphene-based materials doped with nitrogen and 2 and 10 wt % transition metals (Fe, Co, Mn, Cu, Ni and Rh), denoted as rGO/M 2 and 10 %, capable of reducing molecular oxygen. Firstly, nitrogen-doped reduced graphene oxide with atomically dispersed transition metal materials were synthesized using commercial graphene as precursor. A sequential extra-exfoliation and oxidation of the graphene increased the d-spacing between carbon layers and created porosity on the structure, which is essential for the diffusion of reactants on the material. Further simultaneous N doping and reduction of graphene oxide using thermal and low-temperature plasma treatment allowed the formation of M-Nx active sites that contribute greatly on the ORR activity. The obtained carbon structure exhibited a large specific surface area (c.a. 800 m2 g-1) doped with c.a. 1.98 wt % of nitrogen. The incorporation of atomically dispersed metal reached 21 % of 2 wt %, 3 % and 0.46 % of 10 wt % using different reduction methods. The engagement of aromatic macrocycle molecules, particularly iron and cobalt metalloporphyrins, in the graphene oxide structure was also studied. The synthesis of these hybrid materials was based on a procedure described previously, relying on the addition of the metalloporphyrin to the graphene structure, followed by its pyrolysis under N2 atmosphere. The ORR electrochemical characterization of the materials was performed using hydrodynamic convective systems: the rotating disk electrode (RDE) and the rotating ring-disk electrode (RRDE), in acidic, alkaline and neutral media. Among all the synthesized materials, iron- and cobalt-based materials showed the highest performance towards ORR. In particular rGO/Fe 2 % exhibited a remarkable activity in acidic (Eonset 0.76 V vs. RHE), alkaline (Eonset 0.91 V vs. RHE) and neutral (Eonset 0.78 V vs. RHE) media, comparable to Pt/C catalysts. A mixed 2- and 4-electron pathway was observed for rGO/Fe 2 % in acidic and alkaline media due to the contributions of several functional groups in the structure. The remaining materials displayed lower onset potential in acidic (0.44 to 0.71 V vs. RHE), alkaline (0.80 to 0.87 V vs. RHE) and neutral (0.64 to 0.74 V vs. RHE) media. The outstanding ORR performance of these materials is attributed to the presence of M-Nx actives sites dispersed in the carbon structure and intrinsic ORR activity of metalloporphyrins.
Chien-JuiLo y 羅建睿. "Fabrication of Co-based metal-organic frameworks/ N-doped reduced graphene oxide nanocomposites as bifunctional electrocatalysts for Zn-air batteries". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/cxkg4p.
Texto completoLeelavati, A. "Nanostructured Hybrids with Engineered Interfaces for Efficient Electro, Photo and Gas Phase Catalytic Reactions". Thesis, 2015. http://etd.iisc.ernet.in/2005/3849.
Texto completoSarkar, Sujoy. "Electrocatalytic Studies on Layer-type Ternary Phosphochalcogenides and on the Formation of Nitride Phases". Thesis, 2014. http://hdl.handle.net/2005/3027.
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