Enhancing nitrate electroreduction for ammonia production over electron-deficient Co3O4 with La doping regulation

• • La doping elevates NH3 Faradaic efficiency to 96.36% (vs. 87.78% for undoped Co3O4) and NH3 yield to 537.44 μmol h−1 cm−2 (vs. 279.4 μmol h−1 cm−2), effectively doubling productivity while suppressing HER—critical for reducing separation costs and enabling economically viable decentralized NH3 synthesis. • • The Zn–NO3− battery incorporating La-Co3O4/CC achieves a peak power density of 9.86 mW cm−2, demonstrating that nitrate removal can be coupled with energy recovery, offsetting operational costs in wastewater treatment plants. • • DFT calculations confirm that La doping induces electron deficiency at Co sites, lowering the NO3− adsorption energy barrier and optimizing hydrogenation steps, which explains the enhanced selectivity and activity at the atomic level. • • The catalyst exhibits stable operation for at least 24 h with no significant degradation in FE or yield, indicating robust structural integrity under continuous electrocatalytic conditions, a prerequisite for industrial deployment.