Ampere-level plasma-electrosynthesis of ammonia via a Cu⁰/Cu⁺-enriched heterogeneous catalyst

Electrochemical reduction of waste nitrogen-containing salts such as nitrite (NO₂^-) and nitrate (NO₃^-) to NH₃ provides a sustainable waste-to-value strategy for nitrogen recycling. However, the development of efficient electrocatalysts with abundant active sites to boost catalytic efficiency remains a significant challenge. Herein, we report the synthesis of a Cu@CuMoO_4-x heterostructure supported on nickel foam (Cu@CuMoO_4-x/NF) via an electrochemical reconstruction strategy. Unlike conventional Cu-based catalysts, the introduction of the CuMoO_4-x support establishes a robust interfacial coupling that optimizes electron redistribution and stabilizes catalytically active Cu⁰/Cu⁺ species. Benefiting from this interfacial synergy, the Cu@CuMoO_4-x/NF catalyst achieves a low potential of -0.77 V vs. RHE at 1000 mA cm^-2, along with a high Faradaic efficiency of 94.2 % and an NH₃ yield rate of 4.83 mmol h^-1 cm^-2 at -0.8 V vs. RHE. In situ characterizations confirm that the enriched heterointerfaces and abundant Cu⁰/Cu⁺ species accelerate the kinetics of nitrogen intermediates formation, ensuring efficient NH₃ production. Importantly, the Cu@CuMoO_4-x/NF catalyst also demonstrates excellent performance in a Zn-NO₂^- battery with a remarkable power density of 8.63 mW cm^-2, as well as in a paired-electrolysis system that efficiently converts plasma-treated nitrite electrolytes and plastic hydrolysates into value-added NH₄Cl and HCOOK chemicals.