Electrocatalytic nitrite-to-ammonia reduction on isolated Cu sites.

We report that isolated Cu atoms anchored on MnO nanowires (Cu/MnO) can be an effective catalyst towards the electrocatalytic NO-to-NH reduction (NORR). A combination of experiments and theoretical calculations reveals that isolated Cu sites can effectively activate NO, lower the energy barrier of *NO→*NOH rate-determining step and suppress the competitive hydrogen evolution, thus facilitating both activity and selectivity towards the NORR. As a result, Cu/MnO shows the maximum NH-Faradaic efficiency of 93.3% with a corresponding NH yield rate of 439.8 μmol h cm at -0.7 V vs. RHE, together with an excellent electrocatalytic durability.