Nitrite Electroreduction to Ammonia Promoted by Molecular Carbon Dioxide with Near‐unity Faradaic Efficiency
Yangyang Zhang, Yuan Wang, Lu Han, Shengnan Wang, Tengda Cui, Yifan Yan, Ming Xu, Haohong Duan, Yun Kuang, Xiaoming Sun
Abstract
Abstract Electrochemical reduction of nitrite (NO 2 − ) offers an energy‐efficient route for ammonia (NH 3 ) synthesis and reduction of the level of nitrite, which is one of the major pollutants in water. However, the near 100 % Faradaic efficiency (FE) has yet to be achieved due to the complicated reduction route with several intermediates. Here, we report that carbon dioxide (CO 2 ) can enhance the nitrite electroreduction to ammonia on copper nanowire (Cu NW) catalysts. In a broad potential range (−0.7∼−1.3 V vs. RHE), the FE of nitrite to ammonia is close to 100 % with a 3.5‐fold increase in activity compared to that obtained without CO 2. In situ Raman spectroscopy and density functional theory (DFT) calculations indicate that CO 2 acts as a catalyst to facilitate the *NO to *N step, which is the rate determining step for ammonia synthesis. The promotion effect of CO 2 can be expanded to electroreduction of other nitro‐compounds, such as nitrate to ammonia and nitrobenzene to aniline.