Preparation And Reasearch Of A Series Of Graphene Supported PtCu Electrocatalysts For Methanol Electrooxidation Reaction

Direct methanol fuel cells(DMFCs),with methanol as raw materials,is an approach that converts directly the chemical energy into electrical energy.Considerable attentions have been attracted because of their environmental friendliness,high energy conversion efficiency,low emissions,and simple device fabrication.From the point of view of thermodynamic,electrocatalytic oxidation of methanol is prone to occur.However,in fact,the relatively poor methanol oxidation kinetics significantly limit the methanol oxidation reaction.Currently,there are two main ways to promote the rate of methanol electrocatalytic oxidation:First,the research of the type and preparation methods of the electrocatalysts;and the second is the study of electrocatalyst supports.Graphene is a new carbon material with significant electrical conductivity,large surface area,good thermal conductivity,mechanical properties,etc.This paper mainly aims at researching DMFCs anode catalysts.Graphene oxide was synthesized according to the modified Hummers method.Using graphene oxide as precursor to develop different synthetic method for the synthesis of Pt-based catalyst and research the electrocatalytic oxidation of methanol.The content in this paper in detail is as follows:Section one:We mainly outline the DMFCs composition,structure,working principle,advantages,disadvantages and applications,etc.In addition,the study of DMFCs anode electrode electrocatalysts are introduced in detail,including the electrocatalysts preparation method and their application in DMFCs anode catalyst and the preparation of graphene and doping methods.Section two:Research papers,including one-pot synthesis of reduced graphene oxide supported PtCuy catalysts with enhanced electrocatalytic activity for the methanol oxidation reaction,a high-efficiency microwave-assisted synthesis of PtCu alloy nanoparticles dispersed on three dimensional nitrogen-doped graphene networks for highly efficient methanol electrooxidation,hydrothermal synthesis of graphene supported PtCoCu electrocatalysts for highly efficient methanol electrooxidation.Specific content is as follows:1.The outstanding performance PtCuy(y=1,2,3)alloy nanoparticles supported on reduced graphene oxide(rGO)have been synthesized by a facile,efficient,one-pot hydrothermal synthesis approach.The as-prepared PtCuy/rGO catalysts are comprehensively characterized by X-ray diffraction,X-ray photoelectron spectroscopy,transmission electron microscopy.Cyclic voltammetry,CO-stripping voltammetry and chronoamperometry results reveal that the PtCuy/rGO catalysts have higher electro-catalytic activity,more negative onset oxidative potential,more excellent tolerance ability for CO poisoning and enhanced stability for the electro-oxidation of methano]compared to pure Pt/rGO.A s far as the as-made PtCuy/rGO catalysts are concerned,the PtCu2/rGO exhibits the highest electro-catalytic activity.The mechanism of the promoting effect of Cu on Pt is explained based on the electronic modification effect.The nature of interfacial interactions between the Pt-Cu active metal phase and the rGO supporting materials is crucial to achieving high performance.2.PtCu alloy nanoparticles(NPs)dispersed on three dimensional nitrogen-doped graphene(PtCu/3D N-G)electrocatalysts have been successfully synthesized by a two step process.Firstly,three dimensional nitrogen-doped graphene(3D N-G)hydrogels were achieved by an economical one-step hydrothermal method.Then,PtCu alloy NPs were fabricated and deposited on 3D N-G hydrogels by using a high-efficiency microwave-assisted polyol process.Furthermore,the morphology,composition,structure and activity towards methanol electrooxidation of the as-prepared electrocatalysts are characterized by transmission electron microscopy,scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,cyclic voltammetry and chronoamperometry.It is observed that the PtCu/3D N-G electrocatalysts exhibit enhanced electrocatalytic activity,good durability,and high tolerance to CO poisoning towards the methanol electrooxidation in acid solution than those supported on reduced graphene oxide and XC-72 carbon black.The excellent performance towards the methanol electrooxidation reaction is attributed to the combined effects of uniform interconnected three dimensional porous graphene networks,nitrogen doping,strong binding between metal NPs and 3D N-G and the modified Pt state due to alloying.3.After treated with NaBH4,the obtained graphene is dried under-50℃ to prepare graphene(G).Then used as the carrier to support the PtCoCu nanoparticles(PtCoCu/G)which constructed by using CuCl2·2H2O,H2PtCl6 and COCl2·6H2O as raw materials,oil amine as the reducing agent,oleic acid as the structure-directing agent.Transmission electron microscopy and scanning electron microscopy results show that PtCoCu alloy nanoparticles cover all around the G sheets are highly dispersion.X-ray diffraction result reveals the formation of PtCoCu alloy.Electrochemical test results show that the PtCoCu/G on the oxidation of methanol has higher catalytic activity and stability compared to the PtCu/G,PtCo/G,Pt/C.The study showed that the catalytic activity of tri-metallic catalyst is more excellent than bi-metallic catalyst.This may be due to the role of coordination between the ternary alloy is more stronger.