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 (NO₃RR), but the limited utilization of hydrogen species still constrains overall performance. Herein, we fabricate a self-supported EG-CuO_<i>x</i>@Ni(OH)₂ electrode, in which the CuO_<i>x</i>@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 NO₃^- and the activation ability of Ni sites toward H₂O. Notably, EG directs the oriented growth of Ni(OH)₂ into uniform, dense flower-like nanoclusters on CuO_<i>x</i>, 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_<i>x</i>@Ni(OH)₂ exhibits outstanding NO₃RR 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.