Theoretical Design And Exploration Of Electrocatalysts For Overall Water Splitting And Fast Ion Conductor

With the increasing demand for energy,renewable clean energy,such as solar energy,wind energy,tidal energy and so on,has been widely concerned.But the uneven distribution of time and region seriously hinders their use.In order to adapt the electricity system to the characteristics of renewable energy,the energy storage system has become an important research project.As large-scale energy storage devices,high safety and low cost are the two primary considerations.Electrochemical hydrogen production and batteries are effective ways to achieve scale energy storage.Developing efficient,robust,green catalysts is the major goal in this field.For electrochemical storage,all-solid-state batteries（ASSBs）have emerged as attractive alternatives due to their enhanced safety,higher energy density,longer cycle life and lower cost.For a long time,the development of materials is adopting experience guiding experiment,which leads to long research time and high cost.With the development of computer,Computational Materials plays a more and more important role in material research.In this paper,the microscopic mechanisms of electrocatalytic hydrogen production and ion diffusion in solid electrolyte are studied by DFT,and the existing materials are designed theoretically.The relevant research work is as follows:（1）A new type bifunctional heterostructure electrocatalyst:Ru-Ni/Ru-Ni-O was designed.On the basis of the excellent catalytic performance of Ruand RuO₂,their components and structural design were performed by DFT.First,the influence of Ni doping on the catalytic properties of RuO₂was investigated.WithΔG_O⁰_*-ΔG⁰_HO*descriptor,the OER performance and active sites were investigated after doping.Taking into accountΔG_O⁰_*-ΔG⁰_HO*and the adsorption of water on the surface after doping,it is concluded that Ni doping improves OER activity.For the effect of Ni doping on RuHER performance,different H atom adsorption situations on the surfaces of Ru,Ru-Ni and Pt were explored,and the H atom adsorption Gibbs free energies are calculated.Considering)53(G_H*,the decomposition energy of water and the adsorption of water on the surface of catalyst,it is concluded that Ni doping can effectively improve the catalytic performance of RuHER.The designed nanoheterostructure of Ru-Ni/Ru-Ni-O has both component and structural advantages,and a series of experiments have provided evidences for our prediction.（2）The diffusion mechanisms of intrinsic NaCuZrS₃ are studied by combining AIMD and CI-NEB simulation.It is found Na ion interstitial diffusion has lower barrier than vacancy diffusion in the layered material.Based on the conclusions,NaCuZrS₃has been designed theoretically.Na interstitials introduce into the NaCuZrS₃lattice by La doping,and Li replaces Cu can increase band width.Our findings provide a reference for the later research.Our study also find Van der Waals force correction has great influence on the properties of layered materials in computational simulation.The diffusion of Na ions between layers becomes difficult after adding Van der Waals force correction.It can be seen that the correction of Van der Waals force is very necessary in the study of layered solid electrolytes.