Theoretical screening of single transition-metal atoms anchored Janus MoSSe monolayers as efficient electrocatalysts for nitrogen fixation

Designing efficient nitrogen reduction reaction (NRR) electrocatalysts for ammonia (NH3) synthesis under mild conditions is an attracting and challenging theme in energy electrocatalysis. Herein, the catalytic activity of a series of 3d (Cr, Mn, Fe, Co, Ni), 4d (Mo, Tc, Ru, Rh, Pd) and 5d (W, Re, Os, Ir, Pt) transition-metal (TM) atoms anchored Janus MoSSe monolayers for NRR is systematically explored by means of the first-principles calculations. A four-step NRR screening strategy (Delta G(*N-2) < 0 eV, Delta G(*N-2 -> *NNH) < 0.50 eV, Delta G(*NH2 -> *NH3) < 0.50 eV and Delta G(*N-2) < Delta G(*H)) is designed and applied to 15 TM-MoSSe systems, and only the Mo-, Re- and OsMoSSe stand out. The reaction mechanisms of NRR on Mo-, Re- and Os-MoSSe are all via the distal pathway and exhibit excellent catalytic activity (with the limiting potentials of -0.49, -0.39 and -0.49 V, respectively), especially the Re-MoSSe. The high NRR activity of the Mo-, Re- and Os-MoSSe can originate mainly from the effective activation of N-2, high built-in electrical field and superior electrical conductivity. Present findings may suggest a reliable and effective NRR screening strategy for the design of NRR electrocatalysts and promote the further exploration and development of novel NRR electrocatalysts.