Metal-doping Effect The Performance Of Ru-based Electrocatalyst For Oxygen Evolution Reaction

Electrochemical water splitting plays a key role in the utilization of renewable energy.It is consisted of anodic oxygen evolution reaction and cathodic hydrogen evolution reaction.Improving the anodic oxygen evolution reaction is an important factor to improve the efficiency of electrolysis of water,and finding an efficient and stable catalyst is an important way to improve the electrolysis of water.The catalyst efficiency can be improved by changing the electronic structure and increasing the active sites of the catalyst.Metal-organic framework（MOF）is a new type of porous composite material connected by inorganic metal ions and organic ligands.Metal-organic framework（MOF）has large specific surface area,adjustable pore size and particle size,which is widely used in catalyst preparation.Simulation calculations can be used to design and predict the chemical properties of new materials and explain the materials that have been synthesized.In this paper,Mg-MOF-74 is used as the precursor framework,and RuCl₃ is used for ion exchange with Mg-MOF-74.The exchanged samples are annealed and then applied to the surface of the electrode to fabricate Mg-RuO₂ electrocatalyst with high performance.RuO₂ crystal is used to replace Ruwith metal atoms such as Mg,and O atoms are removed to maintain charge balance to build a model.The analysis results show that:（1）Mg-MOF-74 is used as the precursor,and Mg-RuO₂ nanocrystals material with high oxygen evolution reaction（OER）activity and strong stability is obtained after a series of treatments such as exchange and annealing with RuCl₃.The same ellipsoid shape of Mg-MOF-74 is maintained in morphology,but the size decrease from 1-2 μm to 5-10 nm.Mg-RuO₂ catalyst contains a certain proportion of Mg in the material.The electrochemical test results show that Mg-doping change the performance of RuO₂,and the activity,stability and other electrochemical properties are improved.Compared with commercial RuO₂,Mg-RuO₂ overpotential is increased to about 80 m V,and the stability is increased to more than 30 hours.（2）Through the simulation calculation,it can be effectively explained that the electronic structure of RuO₂ is changed after the doping of Mg.By calculating the energy barrier of Mg-RuO₂,the energy barrier of its oxygen evolution reaction（OER）reaction fall by about 0.14 eV compared with pure RuO₂,and the charge distribution is also changed.This further shows that the charge distribution of RuO₂ changes after Mg doping,and the energy barrier of the oxygen evolution reaction（OER）decreases,which is conducive to the reaction.（3）DFT calculations are carried out to reveal the inherent electron variation induced by the M（Fe,Co,Ni,Cr,V,Zn）dopant.After dopant,the electronic structure is changed compared with RuO₂,indicating that element dopant is beneficial to RuO₂ oxygen evolution reaction（OER）.The DFT calculation shows that the optimization of RuO₂ electrocatalytic performance with transition metal dopant is a feasible method.