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 N2 at low overpotentials can be realized over WO3 with tailored surface oxygen vacancies, as predicted by density functional theory studies and evidenced by an NH3 yield rate of 4.2 μgNH3 h−1 mgcat.−1 and a faradaic efficiency of 6.8% at −0.12 V (vs. the reversible hydrogen electrode). A high NH3 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 N2 fixation.