Theoretical Stuty Of Different Nitrogen-Doped Graphene Catalyzing Oxygen Reduction/Evolution

Nitrogen-doped graphene(NDG)catalyst has excellent catalytic performance for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),which is expected to replace noble metal catalyst.However,the specific material morphology and reaction conditions reported in different reports are different,so the configuration of the dominant nitrogen atom cannot be explained.Considering the superiority of computational simulation in variable control and intrinsic properties,this paper designed the graphite nitrogen(GN),pyridine nitrogen(PDN)and pyrrole nitrogen(PRN)doped NDG model for research,to clarify PDN for favorable configuration,provided the theoretical support for the reasonable design of NDG,and revealed the influence of various factors and mechanism of action.from the theoretical level to The main research contents and conclusions are as follows:(1)The superiority of PDN doping is revealed.Through thermodynamic calculation,it is found that PDN formation is exothermic process.Through reaction path simulation,it is found that PDN doping has the highest catalytic activity on ORR(minimum overpotential 0.44 V,same below)and OER(0.38V),and has prominent four-electron path selectivity and obvious two-electron path inhibition in ORR.Through the analysis of electronic structure,it is shown that the advantage of PDN is due to the negative charge and high spin density.(2)The environmental model of sulfuric acid solution was introduced step by step to reveal the advantages of PDN doping under solvation conditions and the influence of sulfuric acid solution on NDG catalytic performance and the mechanism of action.Through the calculation of the reaction path and electronic structure after the introduction of implicit solvent,it is found that PDN is still the doping configuration with the most catalytic potential(ORR 0.38 V,OER 0.53 V),preferentially choosing the four-electron path,which has good conductivity(minimum band gap 0.02 eV)and a large number of effective doping structures.Through the introduction of implicit solvent,the law of solvation effect improving the catalytic performance of ORR by stabilizing the adsorption of intermediates was clarified.By introducing protons and hydrogen sulfate,it was found that they adsorbed and enriched on the catalyst surface to occupy the effective active site and inhibit the adsorption of oxygen-containing intermediates,thus reducing the catalytic performance of NDG.