Theoretical Study Of Electrochemical Nitrogen Reduction On Single Transition Metal Atoms Supported By Two Dimensional Materials

Ammonia(NH3)is an important industrial raw material that is widely used in various industrial processes.Currently,the production of NH3 in industry still relies on the Haber-Bosch process.While this method not only consumes a lot of energy but also results in a large amount of greenhouse gas CO2 emissions.As the most promising alternative to Haber-Bosch technique,electrocatalytic nitrogen reduction reduction(eNRR)can convert nitrogen into ammonia at room temperature and pressure.However,there are some challenges with eNRR,such as the high potential required by eNRR to drive the reaction and the competitive hydrogen evolution reactions(HER),which result in low yield ammonia.Based on the above problems,single-atom catalysts(SACs)supported on two-dimensional materials are investigated to explore how they convert N2 into highly available NH3 and to reveal the catalytic mechanism.The main research results are as follows:Based on density functional theory calculation,we systematically study the eNRR performance of eighteen two-dimensional 1T-MoSe2-supported transition metal singleatom catalysts(TM@1T-MoSe2,TM=V～Ni,Nb～Pd,Ta～Pt).Through the evaluation of the thermodynamic stability of each TM@1T-MoSe2,calculating the limitingpotential of eNRR and ammonia selectivity on each TM@1T-MoSe2,W@1T-MoSe2 is screened out as a potential catalyst for eNRR.On W@1T-MoSe2,the three N2 molecules are co-adsorbed,and it is found that the eNRR process proceeds along the distal path,and its limiting-potential step is the first protonation hydrogenation step,with a limiting potential of-0.23 V.In addition,the multi-adsorption of N2 on W@1TMoSe2 can effectively suppress the side reaction HER and improve the selectivity of eNRR.Therefore,W@1T-MoSe2 can be used as a potential eNRR catalyst with high activity and selectivity.Furthermore,we carry out a theoretical study to investigate the electrocatalytic nitrogen reduction reaction performance of 18 types of single transition metal atom supported on the gallium vacancies of two-dimensional gallium arsenide monolayer(TM@GaAs,TM=V-Pt).The stability,eNRR activity and ammonia selectivity of the catalysts are evaluated.Among the 18 SACs,Mo@GaAs,W@GaAs,and Re@GaAs are identified as potential high-efficiency eNRR catalysts.A detailed study on the reaction mechanism of eNRR show that the three electrocatalysts exhibit good catalytic activity with limiting-potential of-0.29 V,-0.34 V and-0.25 V via distal pathway,respectively.The limiting-potential step is*N2→*N2H or*NH2→*NH3.This work provides a theoretical insight for the design of new eNRR catalysts.