Exploring microenvironmental configuration effects of Cu-based catalysts on nitrate electrocatalytic reduction selectivity

The reduction of nitrate (NO 3 − ) can mitigate its impact on the environment. The electrochemical NO 3 − reduction reaction (NO 3 RR) offers a green and environmentally friendly approach for sustainable ammonia (NH 3 ) synthesis, yet hindered by the complex reaction pathways. Herein, for the first time, we regulated the atomic structure of Cu-based catalysts to control the product selectivity of the NO 3 RR, and three catalysts with different microenvironmental configurations were successfully synthesized. Cu nanocluster (Cu NC) exhibited state-of-the-art NH 3 selectivity (81.1 %), while Cu diatom (Cu DAC) was inclined to produce N 2 (93.4 %), and Cu single atom (Cu SAC) was more likely to simultaneously produce both NH 3 (44.9 %) and N 2 (51.9 %). A series of experiments and theoretical calculations were performed to unveil the underlying mechanism. It was found that Cu NC can form Cu-O bonds with multiple oxygen atoms of the NO 3 − , facilitating electron transfer and rapid NH 3 synthesis. Cu DAC was more conducive to the formation of N*intermediate, which is crucial for N 2 production. This work provides a novel paradigm to regulate the NO 3 RR pathway and steer product selectivity via the microenvironmental configuration modulation of the electrocatalyst at the molecular level. • Three Cu-based catalysts with different microenvironmental configuration were designed. • The functional properties of catalysts were revealed, each producing different reduction products. • The electrocatalytic characteristics of catalysts were analyzed through electrochemical analyses. • The reduction mechanisms of catalysts were explored using theoretical calculations.