The Study Of Metal Oxides/graphene Composites As Bifunctional Electrocatalysts In Oxygen Evolution Reaction And Oxygen Reduction Reaction

Graphene is a novel carbon material that has two dimensional?2D?planar structure with sp²-bonded monolayer sheet.It shows a unique advantage in the electrocatalytic oxygen evolution reaction?OER?,oxygen reduction reaction?ORR?and hydrogen evolution reaction?HER?due to its large specific surface area,high conductivity,electronic mobility,and stability,which results that graphene has important potential applications in catalysts.Combining with the advantages of metal or metallic oxide and graphene respectively,we successfully fabricate graphene/metal oxides composites with bifunctional catalytic activity.In this thesis,graphene oxide is spontaneously reduced and self-assembled into three dimensional porous networks?3DRGO?on substrate Zinc because of its active reduction property.Then putting the substrate metal which is covered by a black layer of reduced graphene oxide into the corresponding metal salt solution?CoCl₂,NiCl₂,CoCl₂/NiCl₂?to prepare functional graphene composites modified with corresponding metal compound?Co₃O₄@3DRGO,NiO@3DRGO,Co₃O₄/NiO@3DRGO?.The study found that the Co₃O₄@3DRGO catalyst shows better electrochemical performance than that of planar Co₃O₄ and other samples.The lower overpotential and smaller charge transfer resistance at the catalyst/electrolyte interface enhance the catalytic efficiency of the oxygen evolution reaction?OER?.Moreover,the hybrid catalyst is also active in oxygen reduction reaction?ORR?with high durability and excellent immunity toward methanol crossover.As the sample has both the OER and ORR electrocatalytic performance,it has a good application prospect in electrochemical energy conversion and storage devices such as high performance zinc-air battery.