Preparation Of Nickel-based Alloy And Sulfide Catalysts And Its Electrocatalytic Performance Towards Urea Electrooxidation

Hydrogen energy（H₂）is considered to be the most environmentally friendly clean energy with high energy density and zero environmental pollution.Due to the slow kinetics of oxygen evolution reaction（OER）in the electrolytic water reaction and the excessive resistance of the electrolytic system,the voltage required for water electrolysis is relatively large,and the theoretical voltage is about 1.23 V.Compared to the electrolytic water reaction,the voltage required for urea electrooxidation is a smaller value of 0.37 V.Using the electrolytic process to convert urea from urea-rich wastewater to hydrogen is a method that helps to protect the environment and generate clean energy（H₂）.However,six electrons need to be transferred during urea electrooxidation,which actually reduces the reaction kinetics.Therefore,it is very important to find an effective urea electrooxidation catalytic electrode.Therefore,this paper is based on the nickel foundation,through the alloying and vulcanization of its two routes for treatment,which not only can effectively improve the catalytic performance of urea electrooxidation reaction,but also can make the nickel-based catalytic electrode in a long time catalytic reaction has a good stability.The details are as follows:1.The NiCu/NF catalytic electrode loads on nickel foam is prepared by a simple one-step hydrothermal method,and the optimum preparation process is optimized by changing the reaction temperature and reaction time.The results show that the catalytic electrode prepared when the reaction temperature is 160℃and the reaction time is 12 h had the best catalytic performance of UOR and HER.By SEM characterization of NiCu/NF electrodes,it is found that the surface of the electrode has a large number of flower-like nanostructures,which can greatly increase the specific surface area of the electrode and provide a large number of active sites for the reaction,so as to improve its catalytic performance.The electrochemical performance of NiCu/NF electrode is tested.It is found that the overpotential of NiCu/NF electrode is only 1.55 V to reach the current density of 10 m A cm^-2.Therefore,the cost,efficiency and high activity of NiCu/NF electrode are of great help to the development of urea electrooxidation.2.Ni₇S₆-Ce₂S₃/NF catalytic electrode is prepared by hydrothermal synthesis.The optimum preparation conditions show that when the total amount of Ni source and Ce source is 0.1mmol and the ratio of Ni source to Ce source is 5:5,the catalytic performance of UOR and HER is the best.SEM characterization results show that the electrode has rod and ball structure,which can improve the specific surface area of the catalyst,provide a large number of active sites for the reaction and accelerate the mass transfer process on the electrode surface.The electrode is electrochemical tested.Ni₇S₆-Ce₂S₃/NF catalytic electrode is used as the cathode and anode of the total electrolytic cell.The overpotential required to reach the current density of 10 m A cm^-2 is 1.51 V.Therefore,the low cost,high efficiency and high activity of Ni₇S₆-Ce₂S₃/NF catalytic electrode are helpful to the development of urea electrooxidation.3.Mo-Ni₃S₂/NF catalytic electrode is prepared by hydrothermal synthesis.By optimizing the preparation conditions,it is concluded that the catalytic properties of UOR and HER are the best when the Mo source is 1.2 mmol.The SEM characterization results show that the catalytic electrode is composed of nanorods,which can not only greatly improve the specific surface area of the catalytic electrode,but also provide a large number of active sites for the catalytic reaction and accelerate the mass transfer process on the electrode surface.The Mo-Ni₃S₂/NF catalytic electrode is assembled into the cathode and anode of the full electrolytic cell.The overpotential required to reach the current density of 10 m A cm^-2 is 1.44 V,showing excellent performance,and the difference between the test results without urea is 0.1 V.Therefore,the low cost,high efficiency and high activity of Mo-Ni₃S₂/NF catalytic electrode are helpful to the development of urea electrooxidation.