Synthesis And Electrocatalytic Oxygen Evolution Performance Of Oxides Derived From Prussian Blue Analogues Of Metal Organic Frameworks

Nowadays,the research of current energy storage and conversion systems is an important strategy for solving energy challenges.In view of the fact that the oxygen evolution reaction(OER)is the main reason that hinders the high efficiency of the water decomposition reaction,the key to solving the problem is how to improve the efficiency of the oxygen evolution catalyst and take into account the economic cost.Prussian blue analogs(PBAs)are metal-organic frameworks(MOFs).Due to their low cost,unique framework structure and controllable components,PBAs have attracted much attention in the field of electrocatalysis.Prussian blue analogs derivatives could add/improve other properties while preserving Prussian blue’s many advantages.In this paper,transition metal-based(Ni,Co,Fe)PBAs are used as precursors,and they are calcined in air at high temperature to obtain binary metal oxides.After modulating the metal ratio of Ni-Co oxides,characterizing the prepared materials and performing electrochemical performance tests,the effects and reasons of different components and different Ni/Co ratios on the electrocatalytic performance of PBAs derivatives were studied.The main content of the paper is as follows:Firstly,preparing transition metal-based(Ni,Co,Fe)PBAs as precursors through co-precipitation method,then the precursors were calcined at high temperature to obtain PBAs-derived oxides.According to the analysis of the electrocatalysis test results,the Ni-Co oxides show the good OER performance.According to the SEM,TEM and HRTEM images,the catalyst is calcined at high temperature,the frame structure of the nanocubes remain unchanged,and it exhibits a porous structure.Combined with XRD,XPS,BET characterization analysis and ECSA test analysis,the morphology of nanocubes and internal mesopores not only promote the full contact between the electrode material and the electrolyte solution,but also expose a greater number and variety of active sites.Secondly,preparing a serise of PBAs derivates by modulating the molar ratio of Ni/Co,namely Ni-Co-71 oxide,Ni-Co-31 oxide,Ni-Co-11 oxide,Ni-Co-13 oxide and Co-Co oxide.Because Ni and Co in Ni-Co PBAs provide the main active sitess for OER.In the LSV test,the Ni-Co-31 oxides shows the best OER performance among all the PBAs derivates prepareds.Combining the characterization analysis of SEM,TEM,HRTEM,XRD,XPS,BET,and the electrochemical analysis of ECSA,EIS,the reasons of Ni-Co-31 oxides shows best OER performance are small size,largeest specific surface area,largest electrochemical activity surface area and good electrical conductivity.That is to say,the Ni-Co-31 oxide ion transmission path is shorter,and more types and numbers of active sites are exposed between the catalyst and the electrolyte during OER process.