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Synthesis of biohybrid electrocatalysts using electroactive bacteriaJimenez Sandoval, Rodrigo J. 03 1900 (has links)
Environmental pollution and health problems created by fossil fuels have led to the development of alternative energies such as solar and wind energies, hydroelectric power, and green hydrogen. The use of biohybrid materials in the development of this type of alternative energies is recent. Biohybrid materials are a unique type of advanced materials that have a biological component that can be a biomolecule or a whole cell and an abiotic or non-biological component that can be a ceramic, a synthetic polymer, or a metal, among others. They have applications in different fields that range from construction (such as bioconcrete) to catalysis (such as artificial enzymes). There are examples in the literature in which bacteria are hybridized with reduced graphene oxide or manganese oxide to catalyze the oxygen evolution of the electrochemical water splitting reaction that produces green hydrogen. The focus of this dissertation is to synthesize efficient biohybrid catalysts following a whole cell approach using electroactive bacteria as the biological component and metallic precursors that form particles ranging from single atoms, nanoclusters, and nanoparticles as the abiotic component. The Fe molecule that is part of the heme group of C-type cytochromes in the outer membrane of Geobacter sulfurreducens acted as the reduction center that allowed the synthesis and hybridization of the metals with the bacteria. Single atom metal catalyst of Ir, Pt, Ru, Cu, and Pd were synthesized and demonstrated a bifunctional catalytic activity towards the hydrogen evolution reaction and the oxygen evolution reaction. Ni single atoms were also synthesized with excellent activity in the water splitting reactions making this biohybrid catalyst very efficient but also green, as Ni is an abundant and cheap metal. Pd nanoclusters with size-control were synthesized by controlling the metal concentration, dosing, and incubation times and were tested in the electrochemical water splitting. Overall, the findings of these studies provide new knowledge on the field of biohybrid materials by contributing with novel methodologies for the synthesis of these materials and the application in the green hydrogen production with high efficiencies.
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Theoretical Studies of Fuel Cell Reaction Mechanisms: Water and Oxygen on Platinum ElectrodesZhang, Tianhou 08 July 2008 (has links)
No description available.
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Electroless Deposited Transitional Metal Phosphide for Oxygen/Hydrogen Evolution ReactionsZhou, Leyao 08 June 2018 (has links)
No description available.
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Mo-S Chemistry: From 2D Material to Molecular ClustersMa, Lu January 2016 (has links)
No description available.
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INVESTIGATION OF ELECTROCATALYTIC ENERGY CONVERSION REACTIONS ON 2D LAYERED MATERIALS: HYDROGEN EVOLUTION ON MoS2 AND CARBON DIOXIDE REDUCTION ON Ti3C2 AND Mo2CAttanayake, Nuwan January 2019 (has links)
Anthropogenic release of the greenhouse gas carbon dioxide is believed to be a leading cause in the global rise in temperature. The main source of the carbon dioxide released is from combustion of fossil fuels. Thus, its necessary to mitigate the release of CO2, look for alternatives for fossil fuels and capture and sequester or capture and convert CO2 to other useful fuels and chemicals hence creating carbon neutral or carbon negative energy cycles. This thesis work was primarily focused on design, adapt and understand the chemistry of two-dimensional (2D) layered materials, particularly transition metal dichalcogenide (TMD) molybdenum disulfide and transition metal carbides (MXenes) as catalytic materials for the conversion of renewable energy into fuels and chemicals as an alternative for fossil fuels. This investigation was accomplished by combining electrochemistry, state of the art characterization and density functional theory (DFT) calculations. We hypothesized that it would be possible to improve the electrocatalytic hydrogen evolution reaction (HER) on MoS2 by engineering catalytically active sites on the plane, their edges and their interlayer regions. We also hypothesized 2D MXene sheets would serve as good carbon dioxide reduction reaction (CO2RR) catalysts under aprotic conditions. Conceivably the broad impact of this thesis work utilizing experimental and theoretical studies is the realization of transition metal doped metallic MoS2 as a potential candidate towards HER in alkaline conditions. Initially the interlayer region of MoS2 were investigated for the HER by introducing Na+, Ca2+, Ni2+ and Co2+ cations in the interlayers of metallic phase MoS2. Experimental results show that intercalation of cations (Na+, Ca2+, Ni2+, and Co2+) into the interlayer region of 1T-MoS2 to lower the overpotential for the HER. In acidic media the overpotential to reach 10 mAcm-2 for 1T-MoS2 with intercalated ions is lowered by ~60 mV relative to pristine 1T-MoS2 (~230 mV). DFT calculations suggest that the introduction of states from the intercalated metals whether sp or d, to lower the Gibbs free energy for H-adsorption (ΔGH) relative to intercalant-free 1T-MoS2. The DFT calculations suggest that Na+ intercalation results in ΔGH closest to zero, which is consistent with our experiments where the lowest overpotential for the HER is observed with Na+ intercalation. In order to explore the activity of the edge sites of MoS2 and the effect of a conductive support we used a microwave-assisted growth technique to synthesize interlayer expanded MoS2 with a vertically orientation on conductive two-dimensional Ti3C2 MXene nanosheets (MoS2⊥Ti3C2). Judicious choice of reaction temperature allows a control over the density of the edges obtained. Compared to pure MoS2 this unique inorganic hybrid structure allows an increased exposure of catalytically active edge sites of MoS2. The produced materials were investigated as electrocatalysts for the hydrogen evolution reaction (HER) in acidic conditions. The MoS2⊥Ti3C2 catalyst synthesized at 240 0C exhibited a low onset potential (-95 mV vs RHE) for the HER and a low Tafel slope (~40 mV dec-1). The decrease in the overpotential is linked to decrease in the charge transfer resistance of the materials with the electrode and the increased edge site density. In a third study the basal plane of metallic MoS2 was engineered by doping with transition metals Co and Ni to be evaluated as a catalyst for the alkaline HER. Due to a lack of oxygen evolution catalysts that can oxidize water at the anode under acidic conditions, there is an urgency to realize HER catalysts that can efficiently reduce water to hydrogen gas under alkaline conditions. Though metallic MoS2 has an optimum H binding free energy for the HER, the sluggish water dissociation step under alkaline conditions has made the implementation of MoS2 as a catalyst at higher pHs harder. We hypothesized that doping transition metals in the basal plane of metallic MoS2 that can efficiently catalyze the water dissociation step in alkaline conditions would help to reduce the overpotential required for the HER under alkaline conditions. Ni and Co were doped in orthorhombic MoO3 which was then converted metallic MoS2 under hydrothermal conditions. The polarization plots obtained in 1.0 M KOH solution shows a low onset overpotential of -75 mV vs RHE for the 10% Ni doped metallic MoS2 with an overpotential of -145 mV to reach a current density of 10 mA/cm2. Pure metallic MoS2 reaches the same current density at an overpotential of -238 mV vs RHE while samples doped with 10% Co atoms reached 10 mA/cm2 at -165 mV. This improvement in the doped samples is attributed to the improved kinetics of the water dissociation step under the alkaline reaction conditions. DFT calculations suggests that an optimal binding of water for the water dissociation step, H binding free and low free energy of binding for OH intermediates. Rigorous cycling of the catalysts shows extremely high stability with the doped samples while the pure metallic MoS2 loses its activity with continuous cycling. DFT calculations show that the doped samples provide extra stability to the metastable metallic MoS2 thus improving their long-term stability. Photo/electrochemical conversion of CO2 is an important step in the path to renewable production of carbon-based fuels and chemicals. Activity and selectivity have been major concerns on the CO2RR catalysts. The activity of known materials are hindered by the scaling relationship in the binding energies of the many intermediates involved in the CO2RR. Thus, the simplest of CO2RR products CO and HCOOH are of great value. Nano structured precious metals like silver and gold have shown promise as cathode materials for the conversion of CO2 to CO. In this thesis work we evaluate the electrocatalytic properties of Mo2C and Ti3C2 MXenes towards the electrochemical CO2 reduction reaction (CO2RR) as cheaper alternatives for precious metals. Though there have been theoretical predictions of the ability of MXenes with certain composition to have the ability to reduce CO2 to hydrocarbons, there are no experimental findings to support these calculations. In this study we observe very high faradaic efficiencies, ~90% for the CO2 reduction to CO at low overpotentials ~250 mV in acetonitrile/ionic liquid electrolytes on Mo2C MXene while Ti3C2 shows ~65% FE at an overpotential of ~600 mV for the cathodic half reaction. Density functional theory calculations suggests that the enhanced activity of Mo2C relative to Ti3C2 is due to relative lowering of the energy barrier for the initial proton couple electron transfer step of CO2 and the spontaneous dissociation of the absorbed *COOH species to *CO and H2O on the Mo2C surface. The calculations also predict the most probable active sites for the CO2 conversion to be vacant oxygen sites. High selectivity and high FE of CO2 reduction to CO makes these earth abundant materials an attractive electrocatalyst for the CO2RR. / Chemistry
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Preparation and characterization of highly active nano pt/c electrocatalyst for proton exchange membrane fuel cell.Ying, Qiling January 2006 (has links)
<p>Catalysts play an essential role in nearly every chemical production process. Platinum supported on high surface area carbon substrates (Pt/C) is one of the promising candidates as an electrocatalyst in low temperature polymer electrolyte fuel cells. Developing the activity of the Pt/C catalyst with narrow Pt particle size distribution and good dispersion has been a main concern in current research.</p>
<p><br />
In this study, the main objective was the development and characterization of inexpensive and effective nanophase Pt/C electrocatalysts. A set of modified Pt/C electrocatalysts with high electrochemical activity and low loading of noble metal was prepared by the impregnation-reduction method in this research. The four home-made catalysts synthesized by different treatments conditions were characterized by several techniques such as EDS, TEM, XRD, AAS, TGA, BET and CV.</p>
<p><br />
Pt electrocatalysts supported on acid treatment Vulcan XC-72 electrocatalysts were produced successfully. The results showed that Pt particle sizes of Pt/C (PrOH)x catalysts between 2.45 and 2.81nm were obtained with homogeneous dispersion, which were more uniform than the commercial Pt/C (JM) catalyst. In the electrochemical activity tests, ORR was confirmed as a structure-sensitive reaction. The Pt/C (PrOH/pH2.5) showed promising results during chemically-active surface area investigation, which compared well with that of the commercial standard Johnson Matthey Pt/C catalyst. The active surface area of Pt/C (PrOH/pH2.5) at 17.98m2/g, was higher than that of the commercial catalyst (17.22 m2/g ) under the conditions applied. In a CV electrochemical activity test of Pt/C catalysts using a Fe2+/Fe3+ mediator system study, Pt/C (PrOH/pH2.5) (67mA/cm2) also showed promise as a catalyst as the current density is comparable to that of the commercial Pt/C (JM) (62mA/cm2).</p>
<p><br />
A remarkable achievement was attained in this study: the electrocatalyst Pt supported on CNTs was synthesized effectively. This method resulted in the smallest Pt particle size 2.15nm. In the electrochemically-active surface area study, the Pt/CNT exhibited a significantly greater active surface area (27.03 m2/g) and higher current density (100 mA/cm2) in the Fe2+/Fe3+ electrochemical mediator system than the other home-made Pt/C catalysts, as well as being significantly higher than the commercial Pt/C (JM) catalysts. Pt/CNT catalyst produced the best electrochemical activities in both H2SO4 and K4[Fe(CN)6] electrolytes. As a result of the characteristics of Pt/CNTï¼it can be deduced that the Pt/CNT is the best electrocatalyst prepared in this study and has great potential for use in fuel cell applications.</p>
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Preparation and characterization of highly active nano pt/c electrocatalyst for proton exchange membrane fuel cell.Ying, Qiling January 2006 (has links)
<p>Catalysts play an essential role in nearly every chemical production process. Platinum supported on high surface area carbon substrates (Pt/C) is one of the promising candidates as an electrocatalyst in low temperature polymer electrolyte fuel cells. Developing the activity of the Pt/C catalyst with narrow Pt particle size distribution and good dispersion has been a main concern in current research.</p>
<p><br />
In this study, the main objective was the development and characterization of inexpensive and effective nanophase Pt/C electrocatalysts. A set of modified Pt/C electrocatalysts with high electrochemical activity and low loading of noble metal was prepared by the impregnation-reduction method in this research. The four home-made catalysts synthesized by different treatments conditions were characterized by several techniques such as EDS, TEM, XRD, AAS, TGA, BET and CV.</p>
<p><br />
Pt electrocatalysts supported on acid treatment Vulcan XC-72 electrocatalysts were produced successfully. The results showed that Pt particle sizes of Pt/C (PrOH)x catalysts between 2.45 and 2.81nm were obtained with homogeneous dispersion, which were more uniform than the commercial Pt/C (JM) catalyst. In the electrochemical activity tests, ORR was confirmed as a structure-sensitive reaction. The Pt/C (PrOH/pH2.5) showed promising results during chemically-active surface area investigation, which compared well with that of the commercial standard Johnson Matthey Pt/C catalyst. The active surface area of Pt/C (PrOH/pH2.5) at 17.98m2/g, was higher than that of the commercial catalyst (17.22 m2/g ) under the conditions applied. In a CV electrochemical activity test of Pt/C catalysts using a Fe2+/Fe3+ mediator system study, Pt/C (PrOH/pH2.5) (67mA/cm2) also showed promise as a catalyst as the current density is comparable to that of the commercial Pt/C (JM) (62mA/cm2).</p>
<p><br />
A remarkable achievement was attained in this study: the electrocatalyst Pt supported on CNTs was synthesized effectively. This method resulted in the smallest Pt particle size 2.15nm. In the electrochemically-active surface area study, the Pt/CNT exhibited a significantly greater active surface area (27.03 m2/g) and higher current density (100 mA/cm2) in the Fe2+/Fe3+ electrochemical mediator system than the other home-made Pt/C catalysts, as well as being significantly higher than the commercial Pt/C (JM) catalysts. Pt/CNT catalyst produced the best electrochemical activities in both H2SO4 and K4[Fe(CN)6] electrolytes. As a result of the characteristics of Pt/CNTï¼it can be deduced that the Pt/CNT is the best electrocatalyst prepared in this study and has great potential for use in fuel cell applications.</p>
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Catalizadores heterogéneos de rodio y cobalto para la hidroformilación de olefinas y la reacción de evolución del hidrógenoGaldeano Ruano, Carmen Piedad 10 March 2024 (has links)
[ES] La presente tesis doctoral se centra en la investigación y desarrollo de catalizadores avanzados con aplicaciones en la industria química. Desde la síntesis de nanopartículas de Rh2P hasta la exploración de catalizadores de cobalto dopados con heteroátomos, se ha buscado no sólo la eficiencia catalítica, sino también minimizar el impacto de estos procesos, permitiendo la producción de productos químicos esenciales con un menor consumo de recursos. Se ha investigado el proceso de síntesis de nanopartículas de Rh2P soportadas por impregnación húmeda seguida de pirólisis para su uso en reacciones de hidroformilación. Para ello, se han descrito y comparado dos métodos que se diferencian en los precursores empleados: uno a partir de un único precursor de fósforo y rodio y el otro a partir de dos precursores separados. Posteriormente, se ha realizado una caracterización de los materiales que ha permitido relacionar la forma de incorporar el fósforo con la composición de las partículas, determinando que el contenido de óxido de rodio es mayor cuando se emplean dos precursores. Para analizar la contribución del fósforo en el sistema se han preparado nanopartículas de rodio metálico soportadas para estudiar la influencia del fósforo en la composición y el tamaño de partícula. Se han analizado otros aspectos como la carga metálica, la temperatura de pirólisis y el uso de diferentes soportes empleando la microscopía electrónica; y se ha estudiado su capacidad de disociación de hidrógeno mediante ensayos de intercambio isotópico. Tras la caracterización de los materiales, éstos se han empleado como electrocatalizadores en la reacción de evolución del hidrógeno, en la que se ha estudiado su aplicabilidad a pH ácido, básico y neutro con bajas cargas de metal. Se ha demostrado que las especies de Rh2P son más activas que las de Rh metálico en la producción de hidrógeno y que el método de síntesis influye en la actividad catalítica. Para completar los ensayos experimentales, se han realizado cálculos DFT que han permitido comprobar por un lado la influencia de los defectos en la red de Rh2P y por otro, si las capas de carbono son efectivas en la protección de las nanopartículas. Se han aplicado los materiales de Rh y Rh2P en la hidroformilación de olefinas donde se ha estudiado la actividad catalítica, la influencia del fósforo y la estabilidad de los catalizadores. Se ha demostrado que el material Rh2P-1@C, obtenido a partir de un solo precursor de rodio y fósforo, es un sustituto viable del catalizador homogéneo RhCl(PPh3)3 ya que las energías de activación calculadas son muy cercanas entre sí. Se ha estudiado la influencia de algunos parámetros en la estabilidad del catalizador, como la temperatura de pirólisis a la que se sintetiza el material, demostrando que existe una relación inversa entre la temperatura de pirólisis y la cantidad de metal lixiviado durante la reacción. Otro factor estudiado es el del soporte, donde además del carbón se han empleado óxidos inorgánicos (Al2O3, CeO2, La2O3, ZnO), poniendo de manifiesto la superioridad del carbón como soporte no sólo en términos de actividad catalítica, sino de estabilidad del material. El catalizador Rh2P-1@C ha sido satisfactoriamente probado en reacciones de hidroformilación de etileno en un reactor de lecho fijo y en la reacción de hidroaminometilación. Como alternativa a los materiales de rodio, se han desarrollado catalizadores de cobalto dopados con heteroátomos (fósforo y nitrógeno). Éstos se han empleado en la hidroformilación de olefinas, donde se ha evaluado la influencia del dopaje en la actividad catalítica y en su estabilidad. Se ha comprobado la efectividad del recubrimiento del carbón dopado con nitrógeno al aumentar su estabilidad en comparación con las nanopartículas de cobalto sin recubrir y se ha demostrado que las nanopartículas de Co2P, al contrario que las Rh2P, no son más activas que las de Co metálico. / [CA] Aquesta tesis doctoral es centra en la investigació i la síntesis de nous catalitzadors amb aplicacions en reaccions químics d'interès industrial. Durant el transcurs de la síntesis de les nanopartícules fins a l'estudi de nous catalitzadors, s'ha cercat no únicament l'eficiència catalítica dels processos sinó la disminució de l'impacte dels mateixos. S'ha investigat el procés de síntesis de nanopartícules de Rh2P suportades a través del mètode d'impregnació humida seguida d'un procés de piròlisis, per al posterior ús d'aquests materials en reaccions d'hidroformil·lació. Per tal fi, s'han descrit i comparat dos mètodes de síntesis que es diferencien en els precursors utilitzats: un a partir d'un únic precursor com a font de fòsfor i rodi, i l'altre a partir dels dos precursors - de rodi i fòsfor - per separats. Posteriorment, s'ha portat a terme una caracterització completa de cadascun dels materials preparats que a permès relacionar la forma com s'incorpora el fòsfor el material en funció de la composició de les partícules. Amb l'objectiu d'analitzar la contribució de les espècies de fòsfor en el sistema s'han preparat un material basat en nanopartícules de rodi metàl·lic suportades. S'han analitzat, mitjançant la microscòpia electrònic, com influeixen en aquest paràmetre altres aspectes, com ara: la càrrega metàl·lica, la temperatura de piròlisis i l'ús de diferents suports. Tanmateix, s'ha estudiat la capacitat dissociativa de l'hidrogen per part d'aquests materials mitjançant assajos d'intercanvi isotòpic. Després de la caracterització dels materials, aquests s'han utilitzat com a electrocatalitzadors en la reacció d'evolució de l'hidrogen en la què s'ha estudiat la utilització d'aquests materials, utilitzant una baixa càrrega metàl·lica, en diferents medis (pH àcid, bàsic i neutre). Els treballs han demostrat que les espècies de Rh2P són més actives que les de Rh metàl·lic i que el mètode de síntesis també influeix en l'activitat catalítica. Per a completar la part experimental, s'han realitzat càlculs DFT que han permès comprovar tan la influència dels defectes de la xarxa de Rh2P com la influència de les capes de carboni en quant a la protecció de les pròpies nanopartícules. Tot seguit, els materials de Rh y Rh2P s'han aplicat en la reacció d'hidroformil·lació d'olefines on s'ha estudiat l'activitat catalítica, la influència de les espècies de fòsfor i l'estabilitat dels catalitzadors utilitzats. S'ha demostrat que el material de Rh2P-1@C, obtingut a partir d'un sol precursor de rodi i fòsfor, pot convertir-se en un possible candidat per a substituir el catalitzador homogeni RhCl(PPh3)3. També, s'ha estudiat la influència d'alguns paràmetres relacionats amb l'estabilitat del catalitzador, com ara la temperatura de piròlisis i la quantitat de metall lixiviat durant la reacció. Una altre factor que ha estat objecte d'estudi és el suport, on a més a més del carboni s'han utilitzat òxids inorgànics - Al2O3, CeO2, La2O3 i ZnO - posant de manifest la superioritat del carboni com a suport; no només en termes d'activitat catalítica sinó d'estabilitat del propi material. A més a més, el catalitzador Rh2P-1@C s'ha provat satisfactòriament en reaccions d'hidroformil·lació de l'etilè en un reactor de tipus llit fix, i en la reacció d'hidroaminometil·lació. Com a alternativa als materials de rodi, s'han sintetitzat catalitzadores de cobalt dopats amb heteroàtoms (fòsfor i nitrogen). Aquests materials, s'han utilitzat en la reacció d'hidroformil·lació d'olefines, on s'ha estudiat la influència del dopatge en l'activitat catalítica i en la seva estabilitat. S'ha comprovat que l'efectivitat del recobriment del carbó dopat amb nitrogen augmenta l'estabilitat del catalitzador en front de les nanopartícules de cobalt sense recobriment, i s'ha aconseguit demostrar que les nanopartícules de Co2P, a diferència de les de Rh2P, no resulten ser més actives que les de Co metàl·lic. / [EN] The present doctoral thesis focuses on the research and development of advanced catalysts with applications in the chemical industry. From the synthesis of Rh2P nanoparticles to the exploration of cobalt catalysts doped with heteroatoms, the primary goal has been to enhance not only the catalytic efficiency but also to minimize the environmental impact of these processes. In a time where the transition to clean energy sources and environmentally friendly processes is of utmost importance, advances in catalysis and material synthesis play a crucial role in the quest for more sustainable solutions in the chemical industry. The synthesis of supported Rh2P nanoparticles by wet impregnation followed by pyrolysis has been investigated. Two methods, differing only in the precursors employed, have been described and compared: one using a single precursor of phosphorus and rhodium, and the other using two separate precursors. Material characterization has revealed the relationship between the method of phosphorus incorporation and particle composition, demonstrating that the rhodium oxide content is higher when two separate precursors are used. Additionally, supported metallic rhodium nanoparticles were prepared to study the influence of phosphorus on particle size and composition. In this chapter, other factors have also been analyzed such as metal loading, pyrolysis temperature, and the use of different supports, employing electron microscopy. Finally, the hydrogen dissociation capacity of the catalysts has been compared through isotopic exchange assays, and the presence of carbon patches around the nanoparticles has been studied using Raman spectroscopy. Following material characterization, these materials have been employed as electrocatalysts in the hydrogen evolution reaction, where their applicability at acidic, basic and neutral pH at one of the lowest metal loadings described has been studied. It has been demonstrated that Rh2P species are more active than metallic Rh species in hydrogen production, and the synthesis method influences catalytic activity. To complement experimental assays, DFT calculations have been performed, allowing for an examination of the influence of defects in the Rh2P lattice and an assessment of the effectiveness of carbon layers in protecting the nanoparticles. Rh and Rh2P materials have been applied in the hydroformylation of olefins, where catalytic activity, the influence of phosphorus, and catalyst stability have been investigated. It has been shown that the material Rh2P-1@C, obtained from a single precursor of rhodium and phosphorus, is a viable substitute for the homogeneous catalyst RhCl(PPh3)3, as their apparent activation energies are very close. The influence of parameters affecting catalyst stability, such as the pyrolysis temperature at which the material is synthesized, has been studied, demonstrating an inverse relationship between pyrolysis temperature and the amount of leached metal during the reaction. Another factor studied is that of the support, where, in addition to carbon, inorganic oxides (Al2O3, CeO2, La2O3, ZnO) have been employed, highlighting the superiority of carbon as support not only in terms of catalytic activity but also material stability. At the end of this chapter, the Rh2P-1@C catalyst has been applied in the hydroformylation of ethylene in a fixed-bed reactor and in the hydroaminomethylation reaction. As an alternative to rhodium materials, cobalt catalysts doped with heteroatoms (phosphorus and nitrogen) have been developed. These catalysts have been employed in the hydroformylation of olefins, where the influence of doping on the catalytic activity and leaching has been evaluated. The effectiveness of nitrogen-doped carbon coating in suppressing leaching has been demonstrated compared to undoped cobalt nanoparticles, and it has been shown that Co2P nanoparticles, unlike Rh2P, are not more active than metallic Co nanoparticles. / Galdeano Ruano, CP. (2024). Catalizadores heterogéneos de rodio y cobalto para la hidroformilación de olefinas y la reacción de evolución del hidrógeno [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203121
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Competitive Adsorption: Reducing the Poisoning Effect of Adsorbed Hydroxyl on Ru Single-Atom Site with SnO for Efficient Hydrogen EvolutionZhang, Jiachen, Chen, Guangbo, Liu, Qicheng, Fan, Chuang, Sun, Dongmei, Tang, Yawen, Sun, Hanjun, Feng, Xinliang 19 January 2024 (has links)
Ruthenium (Ru) has been theoretically considered a viable alkaline hydrogen evolution reaction electrocatalyst due to its fast water dissociation kinetics. However, its strong affinity to the adsorbed hydroxyl (OHad) blocks the active sites, resulting in unsatisfactory performance during the practical HER process. Here, we first reported a competitive adsorption strategy for the construction of SnO2 nanoparticles doped with Ru single-atoms supported on carbon (Ru SAs-SnO2/C) via atomic galvanic replacement. SnO2 was introduced to regulate the strong interaction between Ru and OHad by the competitive adsorption of OHad between Ru and SnO2, which alleviated the poisoning of Ru sites. As a consequence, the Ru SAs-SnO2/C exhibited a low overpotential at 10 mAcm2 (10 mV) and a low Tafel slope of 25 mVdec1. This approach provides a new avenue to modulate the adsorption strength of active sites and intermediates, which paves the way for the development of highly active electrocatalysts.
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Synthesis and Evaluation of PtW Solid-Solution Nanoparticles and Bioactive Metal-Organic Frameworks / PtW固溶体ナノ粒子および生理活性金属-有機構造体の合成と評価Kobayashi, Daiya 24 January 2022 (has links)
京都大学 / 新制・論文博士 / 博士(理学) / 乙第13460号 / 論理博第1577号 / 新制||理||1683(附属図書館) / (主査)教授 北川 宏, 教授 吉村 一良, 教授 竹腰 清乃理 / 学位規則第4条第2項該当 / Doctor of Science / Kyoto University / DGAM
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