TiO2 Anchored Cu Single Atoms Catalysts Boost Nitrite Electroreduction to Ammonia for Water Remediation

Abstract The electrochemical conversion of harmful pollutant nitrite (NO 2 − ) in wastewater to NH 3 is an effective strategy for water remediation and production of value‐added chemicals. However, achieving high NH 3 yield and selectivity is challenging due to the low catalyst activity and competitive H 2 and N 2 H 4 byproducts. Herein, for the first time, Cu single‐atom electrocatalysts on TiO 2 (Cu 1 /TiO 2 ) are designed for nitrite reduction to NH 3 in a neutral aqueous electrolyte. The optimal Cu 1 /TiO 2 exhibits an exceptional NH 3 production rate of 21.2 mg h −1 mg cat −1 and a high NH 3 Faradaic efficiency of 96.0% at −1.0 V (vs RHE), representing one of the best electrocatalytic performance ever achieved. Impressively, the NO 2 − (0.1 mol L −1 ) can be completely conversed in 8 h electrolysis. The experimental studies and theoretical calculations uncover that the single atoms Cu narrows the bandgap of TiO 2 and improves the electron transfer in Cu 1 /TiO 2 , and the single‐atom Cu and TiO 2 synergistically activate NO 2 − , stabilize the *NO intermediate, and reduce the energy barrier of the rate‐determining step (*NH 3 →NH 3 ), thus resulting in remarkable electrocatalytic activity and selectivity for the reduction of nitrite to NH 3 . This study provides a new strategy for simultaneous NH 3 production and water remediation at ambient conditions by using single‐atom catalysis.