Optimizing Oxidation State of Octahedral Copper for Boosting Electroreduction Nitrate to Ammonia
Zhaodong Niu, Shiying Fan, Xinyong Li, Penglei Wang, Moses O. Tadé, Shaomin Liu
Abstract
Electrocatalytic nitrate reduction reaction (NITRR) is a potential candidate for efficient ammonia (NH3) production under ambient conditions in the aqueous media, whereas the direct nine-proton and eight-electron transfer result in low Faraday efficiency and product selectivity. Here, we report that electrochemical NITRR produces NH3 catalyzed by surface oxygen-modified copper nanoparticles wrapped in layered graphitized carbon (Cu@C). The characterization results reveal that Cu@C-800 possesses an optimal oxidation state and exhibits the highest NH3 production Faradaic efficiency of 78 ± 0.9% and a corresponding rate of 51.7 ± 0.6 mmol h–1 g–1 at −0.9 V versus reversible hydrogen electrode. The incorporation of surface oxygen species endows to enhance the binding energy of *NO3 and reduce the energy barrier of *NO to *NOH, the potential rate-determining step. These findings offer a reference for designing efficient catalysts for NITRR to NH3 under ambient conditions.