Computational screening and catalytic origin of transition metal supported on g-t-C3N4 as single-atom catalysts for nitrogen reduction reaction

Abstract

Electrochemically synthesis of NH3 from N2 using single-atom catalysts (SAC) is one of the important strategies for industrial nitrogen fixation and production of chemical raw materials. Herein, in the framework of DFT calculations, the single transition metal (TM) atoms anchored on g-t-C3N4 are systemically studied to screen the potential electrocatalysts for nitrogen reduction reaction (NRR). After a six-step screening process, Fe@g-t-C3N4 and Os@g-t-C3N4 SACs are screened out with good structural stability, high selectivity and high activity. Moreover, the thermodynamic and kinetic stability of Fe@g-t-C3N4 and Os@g-t-C3N4 SACs are demonstrated, suggesting the possibility of experimental synthesis. Furthermore, a series of electronic properties are investigated to uncover the mechanism for the excellent catalytic activity. Generally, three descriptors (ΔG*N, φ, ICOHP) are proposed to elucidate the trend of NRR activity and to establish a physical picture of NRR on TM@g-t-C3N4 from the aspects of energy, intrinsic characteristics and electronic properties. This work provides an effective and reliable procedure to screen out excellent electrochemical NRR catalysts, as well as guidance for the rational design of SAC.