Study On The Structure-activity Relationship Of RuO₂-NiO/NF Heterostructure Electrocatalyst For Hydrogen Evolution Reaction

Rational development of high-efficiency and low-cost water electrolysis hydrogen production catalysts suitable for industrial applications is a powerful strategy to cope with environmental and energy challenges.The heterostructure catalyst constructed by Ru O₂and Ni O has unique physical and chemical properties,which has attracted much attention in recent years.In the existing reports,most of them focus on the preparation,structural characterization and performance test of the catalyst,and the structure-activity relationship between the heterostructure interface and the electrocatalytic hydrogen evolution performance is not deeply explored.Therefore,from the perspective of interface engineering,this paper constructs Ru O₂-Ni O/NF heterostructure electrode,and analyzes the structure-activity relationship of heterostructure catalyst from two aspects of geometric structure and electronic structure,which contributes to the development and application of heterostructure electrocatalyst.In order to select a reasonable composition ratio of the catalyst to improve the kinetics of alkaline hydrogen evolution reaction and to explore the influence of composition on the performance,the Ru O₂-Ni O/NF electrode was prepared with a composition ratio of n_（Ru）∶n_（Ni）=1∶x（x=0.5,1,2）,and characterized by XRD,SEM,XPS and electrochemical performance tests.In Ru O₂-Ni O/NF(n_（Ru）∶n_（Ni）=1∶1),it has the largest number of heterogeneous interfaces,the number of adsorption active sites,and the most effective reactant or intermediate transport space structure.At the same time,it has the best electrochemical performance:the hydrogen evolution overpotential is 56 m V at a current density of 10 m A·cm^-2,the Tafel slope is 47.75 m V·dec^-1,and the C_dlis 28.4 m F·cm^-2.The results show that only increasing the component Ru O₂or Ni O does not affect the electrode activity.The change of composition ratio does not affect the phase structure and valence state of the catalyst,but has a direct effect on the microstructure and electrochemical performance of the electrode.The number and distribution of Ru O₂/Ni O heterogeneous interface may be the key factor.Furthermore,the number and distribution of heterostructure interfaces are adjusted by changing the mixing state,so as to explore the influence of interfaces on the microstructure and properties of catalysts.By means of SEM,CBS,HRTEM,XPS and electrochemical performance tests,the effects of heterogeneous interface on the performance of Ru O₂-Ni O/NF(n_（Ru）∶n_（Ni）=1∶1)electrodes were investigated.Among them,the electrode prepared by uniform mixing has the most uniform distribution,the largest number of Ru O₂/Ni O heterogeneous interfaces,and the most excellent electrochemical performance.The direct stacking of catalytic components has little effect on the performance of the catalyst,while the rich heterogeneous interface formed by uniform mixing directly affects the geometric structure and electrochemical performance of the catalyst.On the basis of the above research,this paper further analyzes the HER mechanism of uniform Ru O₂-Ni O/NF(n_（Ru）∶n_（Ni）=1∶1)catalyst by DFT calculation,and clarifies the special synergistic effect of the heterogeneous interface.Through the analysis of bader charge and differential charge density diagrams,and the calculation of adsorption energy of different reactive adsorbates on the interface,it is proved that the heterostructure interface is the core of the catalyst performance improvement.The charge transfer on the interface leads to the generation of double active sites,so that different types of adsorbates are selectively adsorbed at different active sites,which synergistically promotes the elementary reaction steps of the hydrogen evolution reaction,making the catalyst excellent in the alkaline hydrogen evolution reaction and improving the overall alkaline hydrogen evolution reaction kinetics.In summary,this work successfully constructed Ru O₂-Ni O/NF heterostructures from the perspective of interfacial engineering synergistic catalysis,and discussed the structure-activity relationship and catalytic mechanism from the perspective of geometric structure and electronic structure,providing a new idea for the construction of transition metal-based compound heterostructure catalysts and their application in the field of electrocatalysis.