Preparation Of Nickel-Based Oxygen Evolution Electrode By Gradient Electrodeposition Method And Electrolysis Water Performance

Hydrogen energy is expected to be an ideal energy carrier with the advantages of high energy density,no pollution-free products and coupling with multiple energy sources in the future energy system.The widespread use of hydrogen energy can further accelerate the realization of the strategic goals of carbon peaking and carbon neutrality.The simple process of hydrogen production by water electrolysis is the most ideal green method of hydrogen production.However,hydrogen production by water electrolysis process consumes a lot of electric energy,which severely limits its scale development.Therefore,seeking an economical and stable electrocatalyst could lead to a wide application of electrolytic water technology.In this thesis,the Ni S/NF catalytic electrode based on nickel foam was prepared by gradient current density deposition method.The optimal deposition process parameters were determined by adjusting the deposition solution concentration,deposition solution temperature,p H value and deposition time,and Ni SCo/NF,Ni SMn/NF and Ni SP/NF catalytic electrodes were prepared by introducing metallic and non-metallic elements in electrodeposition solution.（1）The Ni SCo/NF catalytic electrode was successfully prepared by the gradient current density deposition method based on the optimization of the deposition process parameters of Ni S/NF electrode and the introduction of the transition metal element Co.Ni SCo/NF electrode was characterized by XRD,SEM,TEM and XPS.The results showed that the successful doping of Co elements optimized the electronic structure of Ni,and the Co S compound formed as the main active sites of the electrode were located at the crystalline and amorphous nano-edge,which accelerated the electron transfer rate during the oxygen evolution reaction.The unique hierarchical structure of the Ni SCo/NF electrode exposed a large number of active sites and ensured the stability of the electrode.Due to the gradual increase of current density during the deposition process,the Ni SCo/NF electrode exhibited a unique branch-like structure that effectively enhanced the elctrocatalytic performance of the electrode.（2）Ni SMn/NF oxygen evolution catalytic electrode was successfully prepared by gradient current density deposition method,which was optimized based on the deposition parameters of Ni S/NF electrode,and the metal element Mn was introduced.The microstructure and morphology of the electrode was characterized,and it was found that the Ni SMn/NF electrode exhibited a hierarchical cellular structure,which was conducive to the release of gas and full contact with the electrolyte during the oxygen evolution reaction.The successful doping of Mn element optimized the electronic structure of Ni,and the formed Mn S as the main active site enhanced the conductivity of the electrode and accelerated the OER reaction process of the electrode.Therefore,Ni SMn/NF electrode obtained by gradient current density deposition method had excellent electrochemical properties.（3）Ni SP/NF oxygen evolution catalytic electrode was successfully prepared by gradient current density deposition using the same deposition parameters as Ni S/NF electrode and introducing non-metallic element P.Microstructure and morphology characterization of the electrode revealed that the hierarchical honeycomb structure of the Ni SP/NF electrode was formed by aggregation of nanoparticles of inhomogeneous size.The metal phosphate Ni₂P and sulfide Ni S were the main active sites located at the crystalline and amorphous nano-edge of the electrode,and the synergistic effect between Ni₂P and Ni S accelerated the process of oxygen evolution reaction.Therefore,the Ni SP/NF electrode obtained by the gradient current density deposition method behaved an outstanding electrocatalytic activity.