Dynamic Reconstruction of Cu Catalyst under Electrochemical NO Reduction to NH3

The electrochemical reduction of nitric oxide (NO) to ammonia (NH3) offers a sustainable way of simultaneously treating the air pollutant and producing a useful chemical. Among catalyst candidates, Cu emerges as a stand‐out choice for its superb NH3 selectivity and production rate. However, a comprehensive study concerning its catalytic behavior in the NO reduction environment is lacking. Here, we unravel the dynamic rearrangement of Cu catalysts during NO reduction: the emergence of a bundled nanowire structure dependent on the applied potential. This unique structure is closely linked to an enhancement in double‐layer capacitance, leading to a progressive increase in current density from 236 mA cm‐2 by 20% over 1 h, while maintaining a Faradaic efficiency of 95% for NH3. Characterizations of Cu oxidation states suggest that the nanostructure results from the dissolution‐redeposition of Cu in the aqueous electrolyte, influenced by the interaction with NO or other reactive intermediates. This understanding contributes to the broader exploration of Cu‐based catalysts for sustainable and efficient NH3 synthesis from NO.