Transition metal doped and strain engineered VS−MoS2 as electrocatalysts for N2 electroreduction: A DFT study

Abstract

S vacancy activated MoS2 (VS−MoS2) materials are greatly attractive as electrocatalysts in electrocatalytic N2 reduction reaction (NRR). Herein, we investigate the electrocatalytic NRR performance of transition metal (Cr, Mn, V, W) doped and strain engineered VS−MoS2 using first-principles calculations. For all the designed MoS2s, VS is easy to form due to the small defect formation energy (≤3.48 eV) and determined as active site for N2 adsorption and electrocatalytic NRR. Calculation results show that doping and strain regulate the electrocatalytic activity of VS−MoS2 by altering its electronic properties. When strain is absent, Cr-, Mn-, and V-VS−MoS2 exhibit better electrocatalytic NRR activity than undoped VS−MoS2, while W-VS−MoS2 shows slightly worse activity. However, the above situation changes with applying strain. Moreover, the catalytic activity of all the catalysts firstly decreases and then increases with increasing strain. Further comprehensive considering limiting potential (UL) and Faraday efficiency (FE), Cr-VS−MoS2 under 7 % strain is identified as the best NRR electrocatalyst with both excellent activity (UL = -0.18 V) and high selectivity (FE = 99.44 %). In addition, 5 % and 6 % strained Mn-VS−MoS2 are also good electrocatalysts for NRR with low UL and (-0.45 V and -0.23 V, respectively) and substantial FE (37.69 % and 19.29 %, respectively). Therefore, the electrocatalytic NRR performance of VS−MoS2 could be optimized through transition metal doping and strain engineering. Relevant experimental explores will be encouraged based on our theoretical findings.