Interfacing Engineering Of Nickel-based Electrocatalyst For Hydrogen Generation From Water

With the rapid development of economy and society,human’s demand for energy has become increasingly urgent.It is imminent to explore clean energy with high efficiency and low cost.Hydrogen,with high energy density,high calorific value,extensive sources,and clean and non-pollution,can be used as an ideal substitute for fossil fuels.At present,hydrogen production from electrolytic water is one of the most effective ways for green hydrogen production.Water decomposition involves hydrogen evolution reaction（HER）at the negative tap and oxygen evolution reaction（OER）at the positive tap,but its energy consumption is still high.Therefore,it is imperative to develop stable,low-cost,high-performance catalysts for HER and OER performance.The purpose of this paper is to study transition metal based sulfide and selenide catalysts for hydrogen production from water decomposition by surface modification and nanostructure construction,and reveal the deep reaction mechanism by combining with the calculation software VASP.（1）The two-dimensional Co Ni₂S₄@Ni Co-BDC thin-film heterojunction interface composite structure is constructed based on the interface design.The Ni Co-BDC Bi-metal organic Framework（MOFs）structure containing Ni/Co was accurately prepared by one-step solvothermal method,and then Ni Co-BDC was partially sulfided to prepare a composite structure of Co Ni₂S₄@Ni Co-BDC as a synergistic catalyst.Due to the John-Teller effect between Ni and Co,the porous structure of MOF and the high conductivity of Co Ni₂S₄,these factors enhance the intrinsic activity of the catalyst.First-principles calculations based on density functional theory（DFT）show that the heterojunction interface formed by Ni Co-BDC and Co Ni₂S₄ can effectively promote the electron transfer,optimize the adsorption energy of oxygen-containing products in the oxygen evolution reaction,and improve the catalytic reaction kinetics.For the prepared Co Ni₂S₄@Ni Co-BDC heterostructure,it endows a low overpotential（η）of 266 m V at 10 m A cm^-2,which is lower than the previously reported Ni and Co-based sulfide catalysts.Using this universal and effective strategy to anchor the conductive active material in the multi-vacant MOF can indeed achieve efficient OER performance.（2）The composite structure of precious metal Ru and metal selenide with heterogeneous interface was constructed.Ni Se nanorods were grown on nickel foam by hydrothermal method.Due to the nickel foam（NF）in the low p H Ru Cl₃ solution would be partially oxidized,which will lose electrons and transfer to the Ru³⁺on the Ni Se surface,and the Ru³⁺will be reduced to the metal Ru.Finally,Ru clusters were uniformly loaded on the surface of nanorods.In this composite material,Ru and Ni Se have high-efficiency catalytic activity for HER and OER,respectively,and the high electrical conductivity accelerates the electron transfer during the reaction.This fine-designed nanostructure can not only reveal more active sites,but also has good stability.The construction of heterojunction interface optimizes the electron distribution and interface structure,which greatly improves the overall electrocatalytic performance of the composite Ru@Ni Se,and this is proved by the difference charge density.For the Ru@Ni Se heterostructure,the overpotential required for HER and OER to reach the current densities of 50 m A cm^-2 and10 m A cm^-2 are only 49 m V and 243 m V,respectively.When it is used as both the cathode and anode for electrocatalytic water splitting,the current density of 10 m A cm^-2 can be achieved with 1.53 V of driving voltage.Besides,there was no significant performance degradation over 27 hours of continuous testing.The properties are better than commercial Pt/C||Ir O₂ and Pt/C||Ru O₂ electrode pair.The method used in this paper has the advantages of simple technology,relatively low cost,and the prepared materials has uniform morphology.The internal mechanism of kinetic improvement of catalytic reaction is analyzed based on the First-principles calculations of density functional theory（DFT）,which can be used as a reference for the development of high performance electrolysis water catalyst.