Preparation And Study Of PdCu Nanoparticles Supported On Graphene For Ethanol Electrocatalytic Oxidation

Direct Ethanol Fuel Cells(DEFCs)are considered as economic and environment-friendly renewable energy sources because of the low operating temperature,renewability,low toxicity and high energy density.However,Long-term activity has remained as a tremendous challenge for future application of DEFCs,while the poisoning and agglomeration of metal nanocatalysts become the bottleneck for further improvement.Therefore,developing high performance and low cost electrocatalysts is one of the research key points of DEFCs.At present Pd attracts more attention not only because of its lower cost than Pt,but also its little CO-poisoning effects for electrochemical oxidation for ethanol.Furthermore,adding a second element will improve the activity of electrocatalytic,stability of Pd catalyst.And a suitable supporter will enhances the catalytic performance,such as the graphene,whose special structure determines that it has a large specific surface area and mechanical strength,a strong electron transport capacity and excellent conductivity.It was found that graphene supported precious metals are excellent materials for fuel cell catalysts,not only because it owns excellent performance of both graphene and precious metals,but also they may produce synergies effects with each other,so that graphene supported precious metals have excellent catalytic performance.Herein,we prepare PdCu bimetal nanocatalyts supported on graphene for ethanol electrocatalytic oxidation.We developed a facile one-pot hydrothermal approach to prepare these nanocatalyts.The morphology of electrocatalytic was characterized by SEM and TEM,the component of the nanocatalyst was explored by XPS and XRD,and the electrochemical studies were tested by electrochemical work station,including CV and i-t tests.Thus we prepared two kinds of nanocatalysts.One is the sphere Pd-Cu(P)/RGO nanocatalyst whose average particle sizes of the nanocatalysts are approximately 10 nm.The electrochemical studies revealed the Pd-Cu(P)/RGO nanocatalvst has larger electrochemical active surface area(FCSA) than commercial Pd/C.And the electrochemical studies of ethanol oxidation shows the Pd-Cu(P)/RGO nanocatalyst has more negative onset potential and higher values of If and If/Ib,which demonstrated that Pd-Cu(P)/RGO has higher activity and better long-term activity towards ethanol electrooxidation in alkaline medium than commercial Pd/C.The other one is the flower-like Pd-Cu(F)/RGO nanocatalyst which is the hierarchical flower-like Pd-Cu alloy nanoparticles supported on reduced graphene oxide(RGO).The average particle sizes of the nanocatalysts are around 80 nm.The incorporation of NH3 and metals which lead to the hierarchical flower-like structure,attaching to the RGO surface,synergisticly increasing the surface area of electrocatalysts and acquiring more available active sites.It was found that the change of morphology for catalysts had a great influence on the electrocatalytic performance.Also the electrochemical studies of ethanol oxidation in alkaline medium revealed the highly enhanced electrocatalytic activity towards the ethanol oxidation and better long-term stability of the hierarchical flower-like structure of Pd/Cu(F)-RGO than Pd/Cu(P)-RGO.The significantly enhanced electrocatalytic activity and durability benefiting from hierarchical flower-like morphology and Pd-Cu alloy suggest that the Pd/Cu(F)-RGO could be promising electrocatalyst towards ethanol oxidation in DEFCs,and reveal the great potential of the structure design of the supporting materials for the future design and fabrication of nanocatalysts.