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

Electrocatalytic reduction of nitrate (NO3−) can efficiently transform NO3− into ammonia (NH3), enabling the simultaneous removal of NO3− pollutant from wastewater and the production of NH3. Here, we report the use of rare-earth lanthanum-doped Co3O4 nanowires array on carbon cloth (La-Co3O4/CC) as an efficient electrocatalyst for the conversion of NO3− to NH3. The as-synthesized La-Co3O4/CC demonstrates a remarkable NH3 Faradaic efficiency (96.36%) and NH3 yield (537.44 µmol h−1 cm−2), markedly surpassing its Co3O4 counterpart (87.78%, 279.4 µmol h−1 cm−2). Theoretical computations unveil that the incorporation of La doping promotes NO3− adsorption and optimizes the hydrogenation process, thus enhancing the electroreduction activity of Co3O4 in NO3− conversion and NH3 selectivity. Furthermore, a Zn–NO3− battery incorporating La-Co3O4/CC achieved a peak power density of 9.86 mW cm−2. This work advances the application of Co3O4-based electrodes in electrocatalysis and highlights the effectiveness of rare earth element doping in NO3− reduction reactions.