Single transition metal atom anchored on g-C3N4 as an electrocatalyst for nitrogen fixation: A computational study

Electrocatalytic nitrogen reduction reaction (NRR) provides a green and sustainable way to produce ammonia at ambient conditions. The key to realize highly efficient NRR is the catalysts. To design highly active electrocatalysts for NRR, the multistep mechanism involved in NRR must be clearly unraveled. Herein, single V atoms anchored on g-C3N4 is identified to be an efficient electrocatalyst for NRR by screening single 3d transition metal (TM = Sc to Zn) atoms anchored by g-C3N4 (TM@g-C3N4) through density functional theory calculations. NRR takes place on V@g-C3N4 preferentially through distal path with a relatively low limiting potential of −0.55 V. The outstanding NRR performance of V@g-C3N4 is found from the peculiar electronic structure of V after anchored in the six-fold cavity of g-C3N4 and the good transmitter role of V for electron transfer between NxHy species and g-C3N4. Moreover, the formation energy and dissolution potential indicate that V@g-C3N4 is thermodynamically and electrochemically stable and the aggregation of V atoms is unfavorable thermodynamically, signifying that the synthesis of V@g-C3N4 is feasible in experiments. Our work screens out a superior noble metal-free NRR electrocatalyst and will be helpful for the development of ambient artificial nitrogen fixation.