Unveiling pH‐Dependent Mechanistic Shifts in Cu<sub>2</sub>O‐Catalyzed Nitrate Electroreduction for Selective Ammonia Synthesis
Zizi Wang, Fengchen Zhou, Bo Lv, Jian Yu, Junjun Zhang, Yifan Zhang, Yang Wu, Yong Wang, Wen Luo
Abstract
Abstract The electrocatalytic nitrate reduction reaction (NO 3 RR) offers a sustainable route for ammonia synthesis, yet its practical implementation requires catalysts adaptable to pH fluctuations inherent in industrial wastewater systems. Herein, Cu 2 O nanocubes as a model catalyst is synthesized and decoupled the pH‐dependent reaction mechanisms with systematic experimental investigations. In acid electrolytes, the catalyst exhibited 93.3% faradaic efficiency for NH 3 with a yield rate of 34.6 mg h −1 mg cat −1 at −0.7 V versus. RHE. In contrast, in alkaline and neutral electrolytes, NH 3 synthesis is impeded by the formation of NO 2 ‐ which served as the predominant by‐product. Through operando infrared spectroscopy analysis, proton availability as the pivotal regulator is identified: Acidic media facilitates the further conversion of * NO 2 intermediates into NH 3 via the NOH pathway, whereas H + ‐deficient environments in neutral/alkaline conditions divert reaction flux through the NHO pathway. This mechanistic elucidation establishes proton concentration as a key parameter for steering nitrate‐to‐ammonia conversion efficiency.