Ultrafine nano-copper derived from dopamine polymerization & synchronous adsorption achieve electrochemical purification of nitrate to ammonia in complex water environments

Abstract

Electrochemical-nitrate-reduction-reaction (eNitRR) synthesis of ammonia is an effective way to treat nitrate wastewater and alleviate the pressure of the Haber-Bosch ammonia production industry. How to develop effective catalysts to electrochemically reduce nitrate to ammonia and purify sewage under complex environmental conditions is the focus of current research. Herein, the dopamine polymerization process and the [(C₁₂H₈N₂)2Cu]2+ complex embedding process were run simultaneously in time and space, and ultrafine Cu nanoparticles (Cu/CN) were effectively loaded on nitrogen-doped carbon after heat treatment. Using Cu/CN as the catalyst, the ammonia yield rate and Faradaic efficiency of the electrochemical conversion of NO3− to NH3 are highly 8984.0 µg h−1 mgcat.−1 and 95.6%, respectively. Even in the face of complex water environments, such as neutral media, acidic media, coexisting ions, and actual nitrate wastewater, nitrate wastewater can be effectively purified to form high value-added ammonia. The strategy of simultaneous embedding increases the exposure rate of Cu sites, and the support of CN is also beneficial to reduce the energy barrier of *NO3 activation. This study rationally designed catalysts that are beneficial to eNitRR, and considered the situation faced by practical applications during the research stage, reducing the performance gap between laboratory exploration and industrial applications.