Oxygen vacancy enables electrochemical N2 fixation over WO3 with tailored structure

Electrochemical ammonia production under ambient conditions remains a grand challenge. Herein, we demonstrate that efficient binding and reduction of N 2 at low overpotentials can be realized over WO 3 with tailored surface oxygen vacancies , as predicted by density functional theory studies and evidenced by an NH 3 yield rate of 4.2 μg NH3 h −1 mg cat. −1 and a faradaic efficiency of 6.8% at −0.12 V ( vs . the reversible hydrogen electrode). A high NH 3 faradaic efficiency of up to 12.8% is obtained at an overpotential of only 80 mV, which can even be further improved by increasing the electrolyte pH to suppress the competing hydrogen evolution reaction . This low-cost metal oxide holds great appeal as one of the most promising electrocatalysts for efficient N 2 fixation.