Highly Efficient Electrochemical Nitrate and Nitrogen Reduction to Ammonia under Ambient Conditions on Electrodeposited Cu‐Nanosphere Electrode

Abstract The electrochemical reduction reaction of nitrogenous species such as NO 3 − (NO 3 RR) and N 2 (NRR) is a promising strategy for producing ammonia under ambient conditions. However, low activity and poor selectivity of both NO 3 RR and NRR remain the biggest problem of all current electrocatalysts. In this work, we fabricated Cu‐nanosphere film with a high surface area and dominant with a Cu(200) facet by simple electrodeposition method. The Cu‐nanosphere film exhibits high electrocatalytic activity for NO 3 RR and NRR to ammonia under ambient conditions. In the nitrate environment, the Cu‐nanosphere electrode reduced NO 3 − to yield NH 3 at a rate of 5.2 mg/h cm 2 , with a Faradaic efficiency of 85 % at −1.3 V. In the N 2 ‐saturated environment, the Cu‐nanosphere electrode reduced N 2 to yield NH 3 with the highest yield rate of 16.2 μg/h cm 2 at −0.5 V, and the highest NH 3 Faradaic efficiency of 41.6 % at −0.4 V. Furthermore, the Cu‐nanosphere exhibits excellent stability with the NH 3 yield rate, and the Faradaic efficiency remains stable after 10 consecutive cycles. Such high levels of NH 3 yield, selectivity, and stability at low applied potential are among the best values currently reported in the literature.