Dopant‐Induced Electronic States Regulation Boosting Electroreduction of Dilute Nitrate to Ammonium

Abstract Electrochemically converting NO 3 − into NH 3 offers a promising route for water treatment. Nevertheless, electroreduction of dilute NO 3 − is still suffering from low activity and/or selectivity. Herein, B as a modifier was introduced to tune electronic states of Cu and further regulate the performance of electrochemical NO 3 − reduction reaction (NO 3 RR) with dilute NO 3 − concentration (≤100 ppm NO 3 − −N). Notably, a linear relationship was established by plotting NH 3 yield vs . the oxidation state of Cu, indicating that the increase of Cu + content leads to an enhanced NO 3 − ‐to‐NH 3 conversion activity. Under a low NO 3 − −N concentration of 100 ppm, the optimal Cu(B) catalyst displays a 100 % NO 3 − ‐to‐NH 3 conversion at −0.55 to −0.6 V vs. RHE, and a record‐high NH 3 yield of 309 mmol h −1 g cat −1 , which is more than 25 times compared with the pristine Cu nanoparticles (12 mmol h −1 g cat −1 ). This research provides an effective method for conversion of dilute NO 3 − to NH 3 , which has certain guiding significance for the efficient and green conversion of wastewater in the future.