Facile Synthesis of a Cu3Mo2O9 Nanosheet Array for Electrochemical Reduction of Nitrite to Ammonia in Neutral Solution

Electrochemical nitrite (NO2–) is a promising technology for NO2– removal and a sustainable method for generating valuable ammonia (NH3), but this process is intricate and generates other byproducts. In this work, we propose a facile and low-cost method for the preparation of a Cu3Mo2O9 nanosheet array, which can serve as an efficient electrocatalyst for the reduction of NO2– to NH3. The morphology of Cu3Mo2O9 can be adjusted by controlling the synthesis conditions. In neutral solution, Cu3Mo2O9 achieves a high NH3 yield of 30.46 mg h–1 cm–2 and an outstanding faradaic efficiency of 98.6% with excellent long-term electrochemical stability for NO2– reduction. Density functional theory calculations further reveal the key role of the Cu3Mo2O9 (202) surface and its possible reaction pathways in the electrocatalytic reduction of nitrite.