Preparation Of Ternary Pt-based Nanocatalyst And Its Catalytic Behavior Toward Ethanol Oxidation Reaction

Direct ethanol fuel cell(DEFC),which use liquid ethanol as fuel,can directly convert the chemical energy that stored in ethanol into electrical energy.DEFC is a kind of energy supply system with broad application prospect,which is of great significance for solving the two major problems of energy crisis and environmental pollution that the world faces today.At present,DEFC has attracted considerable attention of researchers all over the world because that the ethanol fuel has the advantages of high theoretical energy density,low toxicity,low cost and production in large scales from biomass fermentation.So far,noble metal platinum(Pt)is the most common anodic catalyst for DEFC.However,the scarce reserves,high price and poor anti-poisoning ability of Pt seriously hinder the commercialization of DEFC.Therefore,preparing a high efficiency and low cost Pt-based alloy anodic catalyst could be an efficient approach to improve the catalytic performance of DEFC.This thesis summarizes the research background of DEFC,introduces the working principle and anodic reaction mechanism of DEFC,reviews the research progress of anodic catalyst for DEFC and analyzes the influence of the catalyst support on the catalytic performance of the catalyst.The thesis research mainly focuses on the controllable synthesis of high efficiency,low cost Pt-based alloy anodic catalyst and further adjustment of the elemental compositions and the support materials of the catalysts for improvement of its catalytic performance toward ethanol oxidation reaction.The enhancement mechanism is investigated for scientific insights.The details are summarized briefly as follows: 1.Pt-based alloy nanoparticles supported on RGO as an anodic catalyst for DEFCThe Pt1Ru0.5Sn0.5 ternary alloy nanoparticles,the Pt1Ru1 binary alloy nanoparticles and the Pt1Sn1 binary alloy nanoparticles were respectively directly grown on reduced graphene oxide by a modified polyol one-step reduction method,which denoted as Pt1Ru0.5Sn0.5-RGO,Pt1Ru1-RGO and Pt1Sn1-RGO catalysts,and the as-prepared catalysts were used as the catalysts for ethanol oxidation reaction in DEFC.For comparison,commercial Pt-C catalyst was investigated under the same experimental conditions.In the experiment,Pt1Ru0.5Sn0.5-RGO exhibits the largest electrochemical active surface area(ECSA)up to 51.7 m2·g-1 Pt,which is 1.49 times larger than that of commercial Pt-C catalyst.As for the catalytic behaviors toward ethanol oxidation reaction,the Pt1Ru0.5Sn0.5-RGO catalyst has 2.07 times higher mass current densities(1287 mA·mg-1 Pt)and 1.38 times higher area current densities(24.89 A·m-2 Pt)than that of commercial Pt-C catalyst.Moreover,the Pt1Ru0.5Sn0.5-RGO catalyst presents the most negative onset potential(-0.633 V)and the best stability in comparison to commercial Pt-C catalyst,Pt1Ru1-RGO and Pt1Sn1-RGO catalysts.The results display that the catalyst that Pt1Ru0.5Sn0.5 ternary alloy nanoparticles directly loaded on reduced graphene oxide(Pt1Ru0.5Sn0.5-RGO)shows the best catalytic activity and stability toward ethanol oxidation reaction,which is ascribed to the excellent properties of reduced graphene oxide and the synergistic effects of alloy Pt,Ru and Sn components,and it offers a great application potential.2.Pt3Ru0.5Cu0.5 ternary alloy nanoparticles supported on different carbon support material toward ethanol oxidation reactionThe porous three-dimensional graphene formed by interlace stacked graphene sheets supported Pt3Ru0.5Cu0.5 ternary alloy nanoparticles(Pt3Ru0.5Cu0.5-3D RGO),the zero-dimensional Vulcan XC-72 carbon supported Pt3Ru0.5Cu0.5 ternary alloy nanoparticles(Pt3Ru0.5Cu0.5-C)and the one-dimensional carbon nanotubes supported Pt3Ru0.5Cu0.5 ternary alloy nanoparticles(Pt3Ru0.5Cu0.5-CNT)were respectively prepared by NaBH4 one step reduction method.The ternary alloy nanoparticles with different support materials were used to catalyze ethanol oxidation reaction,and the catalytic performance of the as-prepared catalysts were compared with that of commercial Pt-C catalyst.Results demonstrate the Pt3Ru0.5Cu0.5-3D RGO catalyst that the porous three-dimensional graphene formed by interlace stacked graphene sheets supported Pt3Ru0.5Cu0.5 ternary alloy nanoparticles has the largest electrochemical active surface area(ECSA,54.8 m2·g-1 Pt).Besides,the Pt3Ru0.5Cu0.5-3D RGO catalyst exhibits the largest mass current density(1378 mA·mg-1 Pt)and current densities(25.14 A·m-2 Pt),the best catalytic activity and stability toward ethanol oxidation reaction.Obviously,the support material that the porous three-dimensional graphene formed by the interlace stacked graphene sheets promotes the uniform deposition and dispersion of the Pt3Ru0.5Cu0.5 ternary alloy nanoparticles and effectively preventes the Pt3Ru0.5Cu0.5 ternary alloy nanoparticles from agglomerating in the process of catalyzing ethanol oxidation reaction,which improves the utilization of Pt in the catalysts.Furthermore,the three-dimensional porous structure of the three-dimensional graphene also improves the mass transfer rate and the electron transport rate during the ethanol oxidation reaction.When compared with the zero-dimensional Vulcan XC-72 carbon and the one-dimensional carbon nanotubes,the support material that the porous three-dimensional graphene formed by the interlace stacked graphene sheets makes the catalytic activity and the stability of the catalysts with the same Pt loading increase,so it is a promising support material with extensive application prospect.In summary,the works in this thesis reveal that the adjustable element compositions of the catalysts and the appropriate catalyst support materials can significantly improve the catalytic activity and stability for DEFC anodic catalyst by combining the synergistic effect of the alloy components with the excellent properties of the support materials.