Plasma-Assisted Synthesis of Ni-Doped Cu-Based Catalyst Shielded by Carbon Overlayer for Ammonia Electrosynthesis.

Abstract

Plasma-enabled N₂ oxidation coupled with electrocatalytic NO_x ^- reduction (pNOR-eNO_x ^-RR) represents a highly promising approach for sustainable, scalable, and distributed NH₃ production under mild conditions. However, the eNO_x ^-RR for NH₃ synthesis is hindered by catalyst degradation, which results in low NH₃ selectivity and poor stability. Here, inspired by solid-state source doping in photolithography, this work reports a rapid plasma shock strategy to build a Ni-doped Cu-based catalyst shielded by a carbon overlayer. It demonstrates long-term stability, maintaining an NH₃ Faradaic efficiency (FE) of 96% for 156 h at a current density of 1000 mA cm^-2. More importantly, this work establishes a continuous-flow pNOR-eNO_x ^-RR system using air and water as feedstocks, achieving an NH₃ yield rate of 5.36 mmol h^-1 cm^-2 with an NH₃ FE of 85%. In situ characterizations and theoretical calculations reveal that the carbon overlayer suppresses electrochemical surface degradation and stabilizes the coexistence of Cu₂O and Cu during eNO₃ ^-RR, while Ni doping simultaneously balances the mismatch between NO₃ ^- adsorption and *H supply and accelerates both processes. This study provides a new approach for designing stable catalysts and offers insights into the pNOR-eNO_x ^-RR system, paving the way for continuous NH₃ production directly from air and water under ambient conditions.