Single-atom transition metal supported on B-doped g-C3N4 monolayer for electrochemical nitrogen reduction

Abstract

Electrochemical reduction of the naturally abundant nitrogen (N2) under ambient conditions is a promising way of ammonia (NH3) synthesis, while the development of a highly active, stable and low-cost catalyst is a challenge for it. Herein, the N2 reduction reaction of TM@g-BC3N4 in electrochemical nitrogen reduction has been systematically investigated by density functional theory (DFT) calculation and compared with that of TM@g-C3N4. It was found that TM atoms are more stable anchored to g-BC3N4 than g-C3N4. The adsorption free energy of N2 molecule on Fe@g-BC3N4 has the greatest change compared with that on Fe@g-C3N4, decreasing by 1.08 eV. The spin charge density around the Fe atom in Fe@g-BC3N4 increases significantly compared with that in Fe@g-C3N4, and the total magnetic moment of the system increases by 3.26 μB. The limiting potential (-0.57 V) of Fe@g-BC3N4 in nitrogen reduction is decreased by 0.06 V compared with that of Fe@g-C3N4 (-0.63 V), and the desorption free energy of ammonia molecules decreases from 1.72 eV to 0.46 eV. Fe atom has higher catalytic activity, ammonia molecule is easier to desorption, nitrogen reduction performance is better. This provides an important reference for the application of g-C3N4-based single atom catalyst in the field of nitrogen reduction.