Composite Catalysts Based On Three-dimensional Graphene Network For Oxygen Evolution Reaction

Graphene, a two-dimensional monolayer sheet of sp2-bonded novel carbon materials, has important potential applications in catalysts due to high conductivity, electronic mobility, stability and large specific surface area. Therefore, it has attracted increasing attention in recent years. In this thesis, we focus on the composite catalysts based on graphene oxide(GO) and transition metal oxides to explore the novle sturcture and unique properties of the graphene-based composite catalysts, which will further expand the applications of graphene in energy strorage and conversion. The main research contents and results are as follows:Firstly, the composite catalyst based on three-dimensional grapheneporousnetwork(PGF) and amorphous cobalt oxide(Co-Pi) has been prepared on FTO by a convenient charge-controlled electrodeposition method successively. The prepared Co-Pi@PGF composite catalyst performs a 3D network, then we test the electrocatalytic activity of the Co-Pi@PGF nanohybrid. Results indicate that graphene networkcan effectively increase the surface area of Co-Pi catalyst and the active catalytic sites in the OER, thus accelerate the reaction rate of catalyst/electrolyte interface and effectively reduced the overpotential of water splitting.Then, by controlling the morphology of Fe Ni-LDH and the network of 3D graphene, we prepare iron-nickel layered double hydroxide(Fe Ni-LDH) nanoplates on three-dimensional(3D) graphene framework as the building scaffold in a one-step hydrothermal process. The study found that the Fe Ni-LDH@3DG/CNTs catalyst shows better electrochemical performance than that of planar Fe Ni-LDH. This unique 3D system apparently possesses lower overpotential and smaller charge transfer resistance, therefore can enhance the catalytic efficiency of the oxygen evolution reaction(OER). Moreover, the hybrid catalyst is also active in theoxygen reduction reaction(ORR), qualifying it as a new type of bi-functional catalyst that could potentiallyapply in the related electrochemical energy conversion and storage fields, such as the metal-air batteries and so on.