Rapid Fabrication of N-, Cu-, and Co-Doped Electrodes with Strong Electronic Coupling by Cold Plasma for Electrocatalytic Reduction of Nitrate to Ammonia

Electrochemical NO_<i>x</i>^- reduction (NO_<i>x</i>RR) is a sustainable technology for ammonia synthesis. The development of a simple, fast, and economical catalytic electrode preparation technique is crucial for large-scale ammonia synthesis. Herein, we propose a plate-to-plate DBD plasma strategy to synthesize the catalytic electrodes M-N/CP (M = Cu, Co, Ni, CuCo, and CuNi), achieving in suit codoping of N and bimetals on carbon paper (CP) at room temperature within 3 h. N-doping improves the metal loading and the NO_<i>x</i>RR performance by forming N-M bonds. The electronic coupling and synergistic effect of Cu and Co sites facilitate the relay conversion of NO₃^- to NO₂^- to NH₃. Notably, the NO₃^- removal efficiency of CuCo-N/CP reaches 82%, with NH₃ yield rate of 346 μg h^-1 cm^-2, and the faradaic efficiency is as high as 86% at -0.58 V vs RHE, which remains competitive in terms of NO_<i>x</i>RR performance. Importantly, wet flue gas denitrification and desulfurization coupled with electrocatalytic reduction can convert NO_<i>x</i> and SO₂ to (NH₄)₂SO₄, Additionally, the maneuverability of plasma technology offers the potential for batch preparation of CuCo-N/CP electrodes for electrochemically driven wet denitrification wastewater valorization.