Bulk and surface dual modification of nickel-cobalt spinel with ruthenium toward highly efficient overall water splitting

The development of highly active and stable bifunctional catalysts toward overall water splitting at large current densities through delicate control of composition and structure is a challenging work. Herein, we combined the Ru-doping of NiCo2O4 spinel (NCO) and the surface modification with Ru nanoparticles through rational design and controllable fabrication (NCRO) as a dual modification method to markedly enhance the overall water splitting. Benefiting from the structure advantages, the synergistic electronic effects and optimal binding strength of the reaction intermediates, the NCRO exhibited excellent performance for both hydrogen evolution reaction and oxygen evolution reaction in alkaline media. The density functional theory calculations suggest that the dual modification could enhanced water dissociation ability, optimized the adsorption energy of reaction intermediates and altered the energy level of the d band center. The bulk and surface dual modification is made on nickel-cobalt spinel (NCO) by ruthenium (NCRO) to enhance the water dissociation ability, optimize the adsorption energy of reaction intermediates and alter the energy level of the d band center. NCRO exhibits outstanding overall water splitting performance at high current density in alkaline media. [Display omitted] •The bifunctional electrocatalyst NCRO was developed through a dual modification method toward overall water splitting•The atomic and electronic structure of the electrocatalysts were detailed analysis.•The NCRO can maintain impressive catalytic activity and stability even at high current density (> 1000 mA cm-2).•The dual modification could optimize the adsorption energy and alter the energy level of the d band center.