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 N 2 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 Fe 2 @CN and Co 2 @CN catalysts, respectively. Owing to its high suppression of hydrogen evolution reactions, Co 2 @CN is a superior electrocatalytic material for a N 2 fixation. Stable Fe 2 @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 N 2 and Fe 2 @CN or Co 2 @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. A series of atom pairs supported in g-CN were explored as electrocatalysts for N 2 fixation based on DFT calculations. A stable Co 2 @CN may be a strongly competitive material for the electroreduction of nitrogen with high selectivity and a relatively low overpotential.