Constructing Ru@C₃N₄/Cu Tandem Electrocatalyst with Dual‐Active Sites for Enhanced Nitrate Electroreduction to Ammonia

Abstract

Abstract Electroreduction of nitrate to ammonia reaction (NO 3 − RR) is considered as a promising carbon‐free energy technique, which can eliminate nitrate from waste‐water also produce value‐added ammonia. However, it remains a challenge for achieving satisfied ammonia selectivity and Faraday efficiency (FE) due to the complex multiple‐electron reduction process. Herein, a novel Tandem electrocatalyst that Ru dispersed on the porous graphitized C 3 N 4 (g‐C 3 N 4 ) encapsulated with self‐supported Cu nanowires (denoted as Ru@C 3 N 4 /Cu) for NO 3 − RR is presented. As expected, a high ammonia yield of 0.249 mmol h −1 cm −2 at −0.9 V and high FE NH3 of 91.3% at −0.8 V versus RHE can be obtained, while achieving excellent nitrate conversion (96.1%) and ammonia selectivity (91.4%) in neutral solution. In addition, density functional theory (DFT) calculations further demonstrate that the superior NO 3 − RR performance is mainly resulted from the synergistic effect between the Ru and Cu dual‐active sites, which can significantly enhance the adsorption of NO 3 − and facilitate hydrogenation, as well as suppress the hydrogen evolution reaction, thus lead to highly improved NO 3 − RR performances. This novel design strategy would pave a feasible avenue for the development of advanced NO 3 − RR electrocatalysts.