Ultrafast Carbothermal Shock Strategy for Engineering Lattice Hydroxyl-Enriched Co-Based Catalysts toward Nitrate Electroreduction

Efficient electrocatalytic reduction of nitrate to ammonia (NRA) offers a promising pathway for environmentally benign ammonia production. Herein, we report a carbothermal shock strategy enabling the ultrafast (11 s) construction of lattice hydroxyl-incorporated CoO/Co3O4 nanosheet arrays. The resulting electrode delivers high NRA activity, achieving an ammonia yield rate of 21.5 mg h–1 cm–2 and a Faradaic efficiency of 93.4% at −0.4 V vs RHE, along with long-term electrochemical stability. Ex situ characterizations reveal that the electrode undergoes an in situ deep reconstruction into the CoO/Co(OH)2 architecture with a large surface area for accelerating charge dynamics. In situ Raman and FTIR, and DFT data disclose a dual-site catalytic mechanism of CoO/Co(OH)2, wherein CoO facilitates NO3– absorption and intermediate stabilization, while Co(OH)2 promotes interfacial water dissociation and proton supply as well as lowers the energy barrier for NH3 desorption. This work provides a rapid synthesis strategy and mechanistic insights into phase reconstruction for boosting nitrate-to-ammonia conversion.