Transient heating synthesis of a highly ordered Ga–Cu intermetallic antiperovskite for efficient ammonia electrosynthesis and ultrastable zinc–nitrate fuel cells†

The electrocatalytic nitrate reduction reaction (eNitRR) shows great prospects in treating nitrate-containing wastewater and substituting the Haber–Bosch process for ammonia production. Cu-based bimetallic compounds (BMCs) are attractive eNitRR catalysts due to their high nitrate selectivity, but their disordered crystal structure has restricted their kinetics and durability. Herein, we propose a heat-refactoring strategy to construct an antiperovskite with regular and ordered Ga–Cu coordination, which bonds via strong p–d orbital-oriented hybridization to balance catalytic activity and crystal stability. As a result, a highly ordered Ga–Cu₃N catalyst delivers an impressive ammonia faradaic efficiency (FE) of 96.48% and a stable yield of 24.36 mg h⁻¹ cm⁻². The fast active hydrogen (*H) generation and low eNitRR energy barrier on Ga–Cu intermetallic facets are unveiled by both theoretical calculation and dynamic experiments. The assembled Zn–NO₃⁻ flow battery based on the Ga–Cu₃N cathode can afford an amazing power density of 23.85 mW cm⁻² and a charge/discharge stability of 120 h with efficient nitrate removal and ammonia recovery, much higher compared to the previously reported catalysts. Our research provides novel insights into designing durable BMC catalysts for neutral nitrate wastewater treatment and renewable utilization.