Transition-metal-atom-pairs deposited on g-CN monolayer for nitrogen reduction reaction: Density functional theory calculations

The development of highly active DFT catalysts for an electrocatalytic N2 reduction reaction (NRR) under mild conditions is a difficult challenge. In this study, a series of atom-pair catalysts (APCs) for an NRR were fabricated using transition-metal (TM) atoms (TM = Sc−Zn) doped into g-CN monolayers. The electrochemical mechanism of APCs for an NRR has been reported by well-defined density functional theory calculations. The calculated limiting potentials were −0.47 and −0.78 V for the Fe2@CN and Co2@CN catalysts, respectively. Owing to its high suppression of hydrogen evolution reactions, Co2@CN is a superior electrocatalytic material for a N2 fixation. Stable Fe2@CN may be a strongly attractive material for an NRR with a relatively low overpotential after an improvement in the selectivity. The two-way charge transfer affirmed the donation-acceptance procedure between N2 and Fe2@CN or Co2@CN, which play a crucial role in the activation of inert N≡N bonds. This study provides an in-depth investigation into atom-pair catalysts and will open up new avenues for highly efficient g-CN-based nanostructures for an NRR.