Efficient electrocatalytic reduction of nitrate to ammonia at low concentration by copper-cobalt oxide nanowires with shell–core structure
Chenhao Xiao, Yaxiao Guo, Jiayuan Sun, Tao Guo, Xinyuan Jia, Shinuo Guo, Guancheng Wu, Yue Sun, Zhaoyang Yao, Liu Yi
Abstract
Electrocatalytic nitrate reduction to ammonia (NO3−RR) for removing nitrate from wastewater is a promising but challengeable technology that is increasingly studied. Herein, we developed an efficient CuOx and CoCuOx composed hybrid catalyst (CoCuOx@CuOx/copper foam (CF)), characteristic of distinctive shell–core nanowires grown on CF substrate with CuOx core and CoCuOx shell. The built-in electric field formed at the interface of the CoO/Cu2O heterostructure promotes NO3− adsorption by modulating the charge distribution at the interface, which greatly improves the ammonia yield rate and Faradaic efficiency. At −0.2 V vs. reversible hydrogen electrode (RHE), CoCuOx@CuOx/CF achieves not only an excellent ammonia yield rate of up to 519.1 µg·h−1·cm−2 and Faradaic efficiency of 99.83% at 1 mM NO3− concentration, but also excellent mechanical stabilities. This study provides a novel pathway to design electrocatalyst for the removal of nitrate from dilute nitric acid solutions (≤ 2 mM).