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

Ammonia (NH3) 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 equivalent to 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 mu g 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. Electrochemically reducing nitrogen-containing molecules could provide less energy-intense routes to produce ammonia than the traditional Haber-Bosh process. Here the authors use a catalyst comprising Cu embedded in an organic molecular solid to synthesize ammonia from nitrate ions.