Efficient Electroreduction of Nitrate into Ammonia at Ultralow Concentrations Via an Enrichment Effect
Zhimin Song, Yan Liu, Yongzhi Zhong, Qing Guo, Jie Zeng, Zhigang Geng
Abstract
Abstract The electroreduction of nitrate (NO 3 − ) pollutants to ammonia (NH 3 ) offers an alternative approach for both wastewater treatment and NH 3 synthesis. Numerous electrocatalysts have been reported for the electroreduction of NO 3 − to NH 3 , but most of them demonstrate poor performance at ultralow NO 3 − concentrations. In this study, a Cu‐based catalyst for electroreduction of NO 3 − at ultralow concentrations is developed by encapsulating Cu nanoparticles in a porous carbon framework (Cu@C). At −0.3 V vs reversible hydrogen electrode (RHE), Cu@C achieves Faradaic efficiency for NH 3 of 72.0% with 1 × 10 −3 m NO 3 − , which is 3.6 times higher than that of Cu nanoparticles. Notably, at −0.9 V vs RHE, the yield rate of NH 3 for Cu@C is 469.5 µg h −1 cm −2 , which is the highest value reported for electrocatalysts with 1 × 10 −3 m NO 3 − . An investigation of the mechanism reveals that NO 3 − can be concentrated owing to the enrichment effect of the porous carbon framework in Cu@C, thereby facilitating the mass transfer of NO 3 − for efficient electroreduction into NH 3 at ultralow concentrations.