Study On The Application Of Nickel-based Sulfide Heterostructure In Water Electrolysis

With the development and progress of modern society,people’s demand for energy is higher and higher.However,due to the excessive use of coal,oil,natural gas and other non-renewable energy,we have a major problem of energy crisis and environmental pollution.Therefore,in order to solve these problems,we need to urgently develop environmentally friendly,pollution-free and renewable new energy.Hydrogen is considered to be the most promising,environmentally friendly and nonpolluting new energy.Among many hydrogen production technologies,the technology of hydrogen production by electrolysis of water has attracted people’s attention.In industry,it is an effective production method to obtain hydrogen by electrolysis of water,but the efficiency of hydrogen production from electrolytic water needs to be further improved in industry.In many studies,the use of efficient catalysts to improve the efficiency of hydrogen production from electrolytic water is an important method.At present,in alkaline environment,precious metal platinum-based catalysts and ruthenium dioxide have high catalytic performance and stability,but the cost of these precious metals is too high,which limits their industrial use.Therefore,it is very important to research and develop catalysts with excellent performance and low cost to replace precious metal electrocatalysts.Among them,transition metal nickel-based materials have attracted wide attention because of their rich resources and good environmental protection.The derived catalyst NiS2 has been widely reported because of its good catalytic activity and unique pyrite structure.NiS2 is a low-cost,clean and promising electrocatalyst material.Because of its unique three-dimensional electronic orbit,it is advantageous to adjust its electronic structure.In this paper,nickel-based nanomaterials were compounded with other sulphide materials to accelerate the reaction rate of alkaline hydrogen evolution and oxygen evolution through the synergistic effect of heterogeneous interface.The electrochemical hydrogen and oxygen evolution properties of the catalyst materials in alkaline environment were improved by adjusting the electronic structure.(1)The design of a bifunctional electrocatalyst with stable performance and low cost is of great significance for full water hydrolysis.In this paper,in-situ MoS2/NiS2 nanosheets(Co-MoS2/NiS2/CP)were prepared on carbon paper by chemical vapor vulcanization for the first time.Based on the co-doping of cobalt and the electronic interaction between MoS2 and NiS2,cobalt doping can effectively change the electronic structure of MoS2/NiS2 heterostructure and adjust the electron density of the catalytic center,which not only accelerates the alkaline hydrogen evolution reaction(HER)of Volmer step,but also optimizes the oxygen-containing intermediate adsorption to promote the oxygen evolution reaction(OER).Therefore,the Co-MoS2/NiS2/CP heterojunction shows a low overpotential in alkaline solution(HER:η10=109 mV,OER:η10=323mV).On this basis,Co-MoS2/NiS2/CP double-electrode alkaline electrolyte was designed for total hydrolysis.When Co-MoS2/NiS2/CP was used as both anode and cathode,the battery voltage of Co-MoS2/NiS2/CP was 1.66V when the current density was 10mA cm-2.This strategy proves the feasibility of synergistic effect to improve the performance of low-cost electrocatalyst.(2)We first prepared ferronickel precursor and then vulcanized it to form heterostructure FeS2/NiS2.Samples with different molar ratios of iron and nickel were prepared by adjusting the ratio of nickel to iron.Through the OER performance test in alkaline solution,it can be determined that when Fe:Ni=1:3,the sample has the best OER performance.Under the current density of 10mA cm-2 in alkaline saline and 1.0 M KOH solution,the overpotential is 294 mV and 256 mV.Tafel slope is 92 mV dec-1 and 42.4 mV dec-1,respectively.The interfacial synergism between heterostructures and the electronic interaction between elements are the reasons for the improvement of the performance of FeS2/NiS2 heterostructure electrocatalysts for OER.