Theoretical Study On The Electrocatalytic Reaction Performance Of Bimetallic Atom Doped Graphene

In order to solve the problem of insufficient energy supply and deteriorating living environment in modern society,it is especially important to develop and utilize clean new energy.Among them,H₂ has become the focus of researchers’attention because of its high energy density,non-polluting products and renewable.At present,the mainstream hydrogen production method is still electrolysis of water.However,the overpotential of the anode side oxygen evolution reaction during the electrolysis of water is too high,which is not conducive to the entire reaction.If the urea oxidation reaction with a lower overpotential can be used to replace the oxygen evolution reaction,the efficiency of the entire catalytic process can be greatly improved.On the other hand,although Pt based materials can effectively catalyze water decomposition reactions,it is difficult to achieve large-scale industrial application due to the high cost and scarce reserves of Pt.Therefore,the preparation of cheap and efficient water decomposition reaction catalysts is a highly concerned topic.Based on the above background,this article conducts corresponding research on the two reactions of urea oxidation and water decomposition.Based on five Ni based bimetallic doped graphene,the performance of different metal atom combinations for urea oxidation and water decomposition reactions was studied.The main research content is as follows:（1）Model construction and electronic structure analysis:Based on the characterization data in the experiment,five bimetallic doped N,O coordinated graphene models were constructed.By calculating the formation energy,it was found that the model with serrated edges and metal sites located at the edges is the most stable.On this basis,a single metal doping model was established for comparison.According to the analysis of density of states and differential charge density,there is a certain interaction between two metal atoms in bimetallic doped graphene,which has an impact on the electronic structure.The internal electronic transmission capacity of bimetallic doped graphene is stronger.（2）Theoretical research on urea oxidation reaction:through the differential charge density diagram after urea adsorption,it is found that the change of charge density of bimetallic doped graphene is concentrated in urea,while the change of charge density of monometallic doped graphene is concentrated in the area of metal sites.By using the bond length and ICOHP analysis,it was found that the internal bonds of urea adsorbed on bimetallic doped graphene are more unstable and prone to fracture and reaction.This indicates that bimetallic doped graphene has more advantages in urea oxidation reaction compared to single metal doped graphene.（3）Theoretical research on water decomposition reaction:Bimetal doped graphene has multiple possible adsorption sites for N,O,and metals.By optimizing the structure of different adsorption sites of key intermediates in hydrogen and oxygen evolution reactions,the sites that can undergo adsorption were selected.The reaction energy descriptors for two reactions were calculated at the sites where adsorption can be completed.The results show that the bimetallic-doped graphene as a whole has good activity in the oxygen precipitation reaction,while the Ni Mo bimetallic-doped graphene has considerable activity in the hydrogen precipitation reaction.This work provides theoretical guidance for the use of bimetallic doped graphene in the electrolysis of water for hydrogen production.