Electrocatalytic nitrate-to-ammonia conversion with ~100% Faradaic efficiency via single-atom alloying

Converting nitrate to ammonia (NH3) with the use of electricity produced from renewable energy provides an alternative and sustainable route for NH3 synthesis under ambient conditions. However, due to the complex mechanism involving eight electrons and nine protons transfer processes in nitrate-to-ammonia conversion, reactions run with Cu-based catalysts for NH3 often exhibit limited selectivity and yield. Here, we report a single-atom Ni-alloyed Cu catalyst that exclusively converts nitrate into NH3 with a maximum Faradaic efficiency of ~100% and a yield rate of 326.7 μmol h−1 cm−2 at − 0.55 V versus reversible hydrogen electrode (RHE). X-ray absorption fine structure evidence and density functional theory calculations reveal that the activated single Ni atom on the Cu catalyst regulates the third protonation step of the electrocatalytic nitrate reduction reaction (eNO3-RR) and increases the interaction between the Ni atom and the crucial NOOH* intermediate, thus decreasing the limiting potential and inhibiting byproduct formation. A rough estimation suggests that the price of fertilizer produced by this single-atom alloyed catalyst through the eNO3-RR is competitive with the Haber-Bosch process. Electrocatalytic nitrate reduction constitutes an alternative and sustainable route for NH3 synthesis under ambient conditions. Here, the authors present a single-atom Ni-alloyed Cu electrocatalyst that exclusively converts nitrate into NH3 with a maximum Faradaic efficiency of ~100%. [Display omitted] •A single-atom Ni-alloyed Cu electrocatalyst that specifically converts nitrate into NH3.•A maximum Faradaic efficiency of ~100% can be achieved on Ni1Cu-SAA.•Incorporated single Ni atom decreases the limiting potential and inhibits byproduct formation.•Fertilizer prices produced by eNO3-RR on Ni1Cu-SAA are competitive with the Haber-Bosch process.