Preparation Of Nickel-molybdenum Nitride Nano Catalysts And Their Performance Exploration On Electrocatalytic Water Splitting For Hydrogen Evolution Reaction

In the process of industrialization,fossil fuels are continuously consumed.Fossil fuels are non-renewable and easily cause serious environmental pollution problems when burned.Therefore,it is crucial to find a new renewable and clean energy source.Hydrogen has the advantages of high energy density and zero carbon emissions,and is considered one of the ideal alternatives to fossil fuels.Hydrogen production by electrolysis of water is an effective way to obtain hydrogen energy.It is well known that Pt-based noble metal catalysts have excellent performance in electrocatalytic hydrogen evolution reaction（HER）,but the high price and low storage capacity limit their wide application in industry.Therefore,it is necessary to develop efficient and inexpensive non-precious metal catalysts for HER.Among them,transition metal nitrides have become one of the hot spots for electrocatalyst research on account of their noble-metal like electronic structure.This paper focuses on the design and synthesis of transition metal nitride electrocatalysts,as following:（1）First,the optimal synthesis conditions of monometallic nitride Mo₂N and its HER catalytic performance optimization are explored.In this chapter,the regulation of the growth morphology of molybdenum nitride nanosheets is achieved by optimizing the ammonium molybdate concentration and nitridation temperature.It was found that when the concentration of ammonium molybdate was 0.4 M and the nitriding temperature was600°C,the prepared Mo₂N electrode had an overpotential of 42 m V at a current density of 10 m A/cm²,which had the best electrochemical hydrogen evolution performance and good stability.（2）Secondly,the optimal HER performance of the bimetallic nitride Mo₂N/Ni Mo N is explored and optimized.This chapter focuses on the formation of nickel-molybdenum nitride bimetallic nitrides based on the doping of Ni elements,which effectively reduces the energy barrier of the hydrogen precipitation reaction step with the synergistic effect of Ni and Mo.The HER test shows that the overpotential of nickel molybdenum nitride is 20 m V at a current density of 10 m A/cm²,which is significantly higher than that of molybdenum nitride,and is superior to the traditional Pt/C catalytic performance.（3）Finally,the self-supported nickel-molybdenum nitride is prepared through the in-situ urea reaction of nickel-molybdenum foam and its corresponding HER performance was also optimized.This chapter focuses on further improving the stability of nickel-molybdenum nitride based on its high catalytic activity through a urea-deposited carrier strategy.In this chapter,Ni Mo O nanosheet precursors with good adhesion were directly prepared in situ on nickel-molybdenum foam support by hydrothermal method,which improved the electrical contact and adhesion between the catalyst and the substrate.The overpotential can reach 38 m V at a current density of 10 m A/cm²,which improves the stability and life of the catalyst.