Heterogeneous single-cluster catalysts (Mn3, Fe3, Co3, and Mo3) supported on nitrogen-doped graphene for robust electrochemical nitrogen reduction

Electrochemical nitrogen reduction reaction (NRR) is one of the most promising alternatives to the traditional Haber-Bosch process. Designing efficient electrocatalysts is still challenging. Inspired by the recent experimental and theoretical advances on single-cluster catalysts (SCCs), we systematically investigated the catalytic performance of various triple-transition-metal-atom clusters anchored on nitrogen-doped graphene for NRR through density functional theory (DFT) calculation. Among them, Mn3-N4, Fe3-N4, Co3-N4, and Mo3-N4 were screened out as electrocatalysis systems composed of non-noble metal with high activity, selectivity, stability, and feasibility. Particularly, the Co3-N4 possesses the highest activity with a limiting potential of −0.41 V through the enzymatic mechanism. The outstanding performance of Co3-N4 can be attributed to the unique electronic structure leading to strong π backdonation, which is crucial in effective N2 activation. This work not only predicts four efficient non-noble metal electrocatalysts for NRR, but also suggest the SCCs can serve as potential candidates for other important electrochemical reactions.