Regulating The Sulfur Vacancies Of Ni₃S₂ And Research On Electrocatalytic Activity Towards Oxygen Evolution Reaction

In recent years,due to its rich phase structure,good stability of oxygen evolution and low cost,the transition-metal sulfides are considered to be excellent catalysts for replacing noble metal and noble metal oxide?RuO₂,IrO₂?.Among them,Ni₃S₂ has become a promising candidate for OER catalyst because of its high conductivity,low cost and excellent catalytic activity.In order to further improving the catalytic performance of Ni₃S₂.This paper proposes a method to regulating sulfur vacancies in Ni₃S₂ through precursor annealing.Firstly,anodization was carried out on the nickel to obtain the precursor.In order to tuning the concentration of oxygen vacancies in precursor,the heat treatment of different annealing process was performed on the precursor.At last,the sulfur-deficient Ni₃S₂ was obtained through hydrothermal.Firstly,based on some experiment results,we found that the concentration of oxygen vacancies in precursor was affected by different temperature and atmosphere.The concentration of oxygen vacancies in precursor were 53%after annealing at 350?under air atmosphere one hour,while the concentration of oxygen vacancies in precursor after annealing under oxygen atmosphere one hour was 28.6%.Then the sulfur-deficient Ni₃S₂ was obtained through hydrothermal.Thees samples were characterized by XPS,EPR,and these results show that the oxygen vacancies in precursor transformed into sulfur vacancies in Ni₃S₂ through hydrothermal process.Furthermore,the sulfur vacancies in Ni₃S₂ can reduce adsorption energy of intermediates or water molecules on the surface of the catalyst,so it can speed up the reaction of catalytic kinetics.Secondly,the comparison and analysis of the electrocatalytic performance of the samples with different hydrothermal process,the data results show that the precursor with air annealing after sulfuration process have good oxygen catalytic activity,the overpotentials of 0.293V are needed to achieve a current density of 10mA/cm² and delivers a high current density of12.1mA/cm² under the overpotentials of 300 mV.Finally,the method of regulating sulfur vacancies are applied to cobalt-base sulfide.This results show that the cobalt precursor with air annealing after sulfuration has good catalytic activity,it indicates that the strategy of regulating sulfur vacancies have expansibility.So this research is helpful to further promote the development and application of transition-metal sulfide catalysts.