Insights into the Origin of Activity Enhancement via Tuning Electronic Structure of Cu[sub.2]O towards Electrocatalytic Ammonia Synthesis

The insight of the activity phase and reaction mechanism is vital for developing high-performance ammonia synthesis electrocatalysts. In this study, the origin of the electronic-dependent activity for the model Cu[sub.2]O catalyst toward ammonia electrosynthesis with nitrate was probed. The modulation of the electronic state and oxygen vacancy content of Cu[sub.2]O was realized by doping with halogen elements (Cl, Br, I). The electrocatalytic experiments showed that the activity of the ammonia production depends strongly on the electronic states in Cu[sub.2]O. With increased electronic state defects in Cu[sub.2]O, the ammonia synthesis performance increased first and then decreased. The Cu[sub.2]O/Br with electronic defects in the middle showed the highest ammonia yield of 11.4 g h[sup.−1] g[sup.−1] at −1.0 V (vs. RHE), indicating that the pattern of change in optimal ammonia activity is consistent with the phenomenon of volcano curves in reaction chemistry. This work highlights a promising route for designing NO[sub.3] [sup.−]RR to NH[sub.3] catalysts.