Electrochemical reduction of nitrate to ammonia via direct eight-electron transfer using a copper–molecular solid catalyst

Ammonia (NH 3 ) is essential for modern agriculture and industry and is a potential energy carrier. NH 3 is traditionally synthesized by the Haber–Bosch process at high temperature and pressure. The high-energy input of this process has motivated research into electrochemical NH 3 synthesis via nitrogen (N 2 )–water reactions under ambient conditions. However, the future of this low-cost process is compromised by the low yield rate and poor selectivity, ascribed to the inert N≡N bond and ultralow solubility of N 2 . Obtaining NH 3 directly from non-N 2 sources could circumvent these challenges. Here we report the eight-electron direct electroreduction of nitrate to NH 3 catalysed by copper-incorporated crystalline 3,4,9,10-perylenetetracarboxylic dianhydride. The catalyst exhibits an NH 3 production rate of 436 ± 85 μg h −1 cm −2 and a maximum Faradaic efficiency of 85.9% at −0.4 V versus a reversible hydrogen electrode. This notable performance is achieved by the catalyst regulating the transfer of protons and/or electrons to the copper centres and suppressing hydrogen production.