Research On The Dopant-regulation And Oxygen Evolution Performance Of Transition Metal-based Electrocatalysts

Environment and energy issues are essential for a sustainable society.Hydrogen as an energy carrier has many advantages,such as high energy density,water as the only product,and zero pollution.The production of hydrogen by electrolysis of water can convert intermittent renewable energy into storable chemical energy and resolve the problem of abandoned renewable electricity,thereby effectively alleviating the energy and environment crisis.The electrolysis of water consists of the anodic oxygen evolution reaction（OER）and the cathodic hydrogen evolution reaction（HER）.The OER is a sluggish four-electron process and requires the use of electrocatalysts to reduce the reaction energy barrier and accelerate reaction kinetics.Compared with Ir O₂and Ru O₂ noble metal-based electrocatalysts,transition metal-based OER electrocatalysts could reduce cost and realize a large-scale application.However,the electrocatalytic activity and stability of current transition metal-based OER electrocatalysts still need to be significantly improved to reduce the cost of hydrogen production and improve energy conversion efficiency.Therefore,this thesis focuses on the dopant-regulation and performance optimization of transition metal-based OER electrocatalysts through the dopant-induced transformation of active sites and the dopant-regulation of the coordination environment of active sites to improve the performance of transition metal-based OER electrocatalysts and promote alkaline water electrolysis technology.The specific works are shown as follows:（1）Zr Doptant-induced shift of active centers:a series of transition metal（Mo,Mn,V,Cu,W,Zr）-doped NiSe₂ nanosheets have been designed and prepared,which were grown on carbon cloth as self-supporting integrated electrodes for alkaline OER.The results show that the dopants（Mo,Mn,V,Cu,W,Zr）increase OER activity compared with NiSe₂ nanosheets,among which,Zr-doped NiSe₂ exhibited the best performance with an overpotential of only 224 m V at 10 m A cm^-2 and a stable operation for at least500 h.Microstructural characterizations,in-situ Raman spectra,and theoretical calculations indicate that NiSe₂ was electrochemically in-situ restructured to NiOOH/Zr-NiSe₂,in which,the Zr via charge transfer induces the transformation of active centers from Nisingle sites to Ni-Se dual-sites.The Ni-Se metal-nonmetal dual-sites dynamically tune the adsorption energy of oxygenated intermediates and overall reaction kinetics.（2）B dopant-regulation of the coordination environment of FeCo/NC:firstly,the influence of the coordination environment of the FeCodiatomic center on the OER performance was theoretically calculated.It was predicted that the FeCodiatom with B and N hetero-coordination has excellent electrocatalytic activity and stability for OER.The B-FeCo/NC catalyst was then synthesized experimentally,and electrochemical tests showed that the B-FeCo/NC has an overpotential of 317 m V at 10 m A cm^-2 and stably operates for at least 50 h.Theoretical calculations coupled with experimental validation help in developing efficient OER electrocatalysts.