Activating Fe3 single clusters for efficient electrocatalytic nitrate reduction reaction by tuning metal-support effect: A DFT study

Electrocatalytic nitrate reduction reaction (NO₃RR) represents a promising green and efficient pathway for ammonia synthesis, owing to its mild reaction conditions. However, significant technological challenges persist in developing electrocatalysts capable of achieving high-selectivity ammonia synthesis. In this study, density functional theory computations are employed to investigate the performance of Fe₃ clusters supported on ten carbon-based substrates (Fe₃/g-X, X = graphene (gra), GDY, N, CN, C₂N, C₃N, C₇N₃, C₉N₄, C₁₀N₃, and C₁₃N₃) in NO₃RR. By evaluating key indicators such as structural stability, adsorption configuration, reaction mechanisms, catalytic activity, and product selectivity, it was found that Fe₃/g-gra demonstrates exceptional catalytic performance under ambient conditions, with a limiting potential of only −0.51 V, and the ability to stably and selectively reduce nitrate to ammonia. Electronic structure analysis elucidates the intrinsic mechanism behind the high activity of this catalyst. Further comparative studies reveal that among Fe₁ to Fe₄ cluster catalysts (Fe_n/g-gra, n = 1–4), Fe₃/g-gra consistently maintains the optimal catalytic performance. These findings not only deepen the understanding of the metal-support effect but also provide significant theoretical and technical guidance for the development of efficient ammonia synthesis electrocatalysts.