Ethylene Glycol-Assisted Interfacial Engineering for Efficient Electrocatalytic Nitrate Reduction to Ammonia at Industry-Relevant Current Exceeding 2 A cm ^–2

Constructing synergistic heterointerfaces is recognized as an effective strategy to enhance the efficiency of electrocatalytic nitrate reduction to ammonia (NO 3 RR), but the limited utilization of hydrogen species still constrains overall performance. Herein, we fabricate a self-supported EG-CuO x @Ni(OH) 2 electrode, in which the CuO x @Ni(OH) 2 heterointerface induces charge redistribution, and the introduction of ethylene glycol (EG) further strengthens electronic coupling between phases, synchronously optimizing the adsorption capability of Cu sites toward NO 3 – and the activation ability of Ni sites toward H 2 O. Notably, EG directs the oriented growth of Ni(OH) 2 into uniform, dense flower-like nanoclusters on CuO x, substantially increasing active site exposure and interfacial contact efficiency. Moreover, EG is beneficial to locally enriching protons, facilitating the efficient hydrogenation of key intermediates by H* species. Benefiting from these synergistic effects, EG-CuO x @Ni(OH) 2 exhibits outstanding NO 3 RR performance, achieving an ammonia half-cell energy efficiency of 39.90%, a Faradaic efficiency of 96.59%, an ammonia production rate of 202.16 mg h –1 ·cm –2, and a current density of 2549.24 mA·cm –2, while maintaining stable operation for 18 h.