Promoted electrocatalytic water splitting by regulating the concentration of oxygen vacancies

Among the many methods of hydrogen production, the electrolysis of water has a broad prospect. In this experiment, NiCo2O4 nanosheets with different degrees of oxidation were synthesized on nickel foam by the hydrothermal method, air calcination and reduction steps. The experimental results show that reduction treatment significantly improved the catalytic activity of NiCo2O4 materials under alkaline medium conditions of 1.0 mol/L KOH. V-NiCo2O4-4 shows better catalytic activity with an overpotential of 285 mV and 340 mV for the oxygen evolution reaction (OER) at 10 mA cm-2 and 50 mA cm-2, respectively. The better catalytic activity of V-NiCo2O4-4 is mainly assigned to the flower-like structure of the catalyst surface and the moderate reduction of NaBH4, resulting in more oxygen va-cancies and active sites. Density functional theory calculation also indicates that the V-NiCo2O4-4 material has a stronger water absorption energy (0.75 eV) compared to the V-NiCo2O4-2 and V-NiCo2O4-6 materials, which provides a new foundation for the con-struction of binder-free high-performance electrodes for water splitting.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.