Electroreduction NO to NH3 over single metal atom anchored on pyrrole type defective graphene: A DFT study

Electrochemical is considered an attractive approach to recycling the pollution NO (NORR) and producing the valuable NH3, which could simultaneously solve the two challenging problems, i.e., NO removal and NH3 synthesis. Current research efforts focus less on NORR due to the lack of effective catalysts. Herein, based on DFT calculation, we try to explore effective pyrrole-type TM-N4 (TM = V, Cr, Mn, Fe, Co, Ni, Cu, Ru, Rh, Ta) catalysts for achieving the direct NORR. Among the investigated systems, Fe-N4 exhibits excellent catalytic activity and high NH3 selectivity. Moreover, the free energy of adsorption of N* has been proposed as a descriptor to predict and screen the effective TM-N4 catalyst for NORR and the crystal orbital halmilton populations (COHP) is used to describe the intrinsic relationship between metal atoms and the adsorption free energy of N* intermediate. This work has provided a theoretical picture of TM-N4 catalyzing NO to NH3, which will establish guidelines for the rational design of NORR catalysts and other electrochemical reactions.