Preparation And Electrochemical Performance Of Non-Noble Metal OER Electrocatalysts

Environmental pollution caused by excessive consumption of fossil energy has greatly promoted the demand for clean,green and sustainable energy.Electrochemical hydrolysis is considered as one of the most promising green for hydrogen production strategies.Among them,the hydrogen precipitation reaction（HER）at the cathode and the oxygen precipitation reaction（OER）at the anode are the keys that affect the efficiency of electrochemical hydrolysis.In particular,OER involves multiple proton and electron transfers and the slow reaction kinetics severely limits its overall efficiency in hydrolysis.Ru and Ir-based metal oxides are currently the most efficient catalysts for oxygen evolution reaction,but their inherent scarcity and high cost have limited their commercial application.However,the scarcity and high cost of the catalyst itself restrict the process of its commercial application.Therefore,the development of efficient and stable non-precious metal-based OER electrocatalysts has become one of the research hotspots in the fields of materials,chemistry and energy.MOFs-derived electrocatalysts have the advantages of high electrochemical surface area,high porosity and improved conductivity and charge transfer.Therefore,in this paper,a series of self-supporting MOFs-derived electrocatalysts were prepared,and their electrocatalytic performance was tuned through the strategies of morphological design,heteroatom doping,construction of heterojunctions and composition optimization,and their mechanisms of action on OER kinetic processes were revealed.The main research contents and results are as follows:1.The CoNiCu-LDH@CuO/CF self-supported electrode was successfully fabricated by using Cu（OH）₂ nanorods array grown in situ,trimetallic CoNiCu-MOF and MOFs-derived LDH microflower structure on copper foam substrate.The three-dimensional layered microfloral structure of the electrocatalyst can expose the catalytic active sites to the greatest extent.Due to the existence of a large number of metal ions and free anions with coordination unsaturated between CoNiCu-LDH layers,the electron and ion transfer rate is effectively improved.In addition,CoNiCu-LDH@CuO/CF has superhydrophilic surface properties,which greatly facilitates the mass transfer of the electrode at high current density.Due to the above advantages,the self-supported electrode has excellent OER performance in alkaline electrolytes,with an overpotential of only 286 m V to achieve a current density of 100 m A cm^-2,while its HER overpotential is only 268 m V.CoNiCu-LDH@CuO/CF electrode also shows excellent complete hydrolysis performance and stability.2.The Ni₂P-Fe₂P/NF self-supported electrode was successfully prepared by a three-step strategy of in-situ growth of Ni（OH）₂ array by hydrothermal method,insertion of NiFe-MOF nanosheets on the surface of Ni（OH）₂ array,and then bimetallic phosphating by low temperature phosphating.The three-dimensional heterogeneous structure of the electrocatalyst can not only provide abundant active centers in full contact with electrolytes and intermediates to promote charge transfer and mass transfer,but also expose the catalytic active sites to the maximum extent.The synergistic effect of Ni-Fe can regulate the electronic structure of the active site and reduce the reaction energy barrier The introduction of P can enhance the corrosion resistance of the electrode,so that it has excellent stability.At the same time,the electron transport performance of the catalyst can be improved,so that more active sites can be generated.Benefiting from the above advantages,Ni₂P-Fe₂P/NF self-supported electrodes exhibit excellent OER activity in alkaline electrolytes,with overpotential as low as 218 and 226 m V at current densities of 100 and 200 m A cm^-2,showing excellent OER performance and stability.These results confirm the rationality of the design of Ni₂P-Fe₂P/NF electrode,and provide a new idea for the preparation of non-noble metal OER electrocatalysts.