Dual-doping of ruthenium and nickel into Co3O4 for improving the oxygen evolution activity

Abstract

Spinel oxides Co₃O₄ with mixed valence cations Co²⁺ and Co³⁺ make it possible to improve the catalytic activity by regulating the distribution of cations via additional doping. Controllable synthesis of nanosized Co₃O₄ with excellent catalytic properties and stability towards the oxygen evolution reaction (OER) is critical for conversion and storage of sustainable source-derived electricity. Herein, Ru and Ni co-doped Co₃O₄ nanoparticles (Ru/Ni-Co₃O₄) with abundant active sites and oxygen vacancies were synthesized by a one-step hydrothermal method. Ru atoms doped into the octahedral sites improve the intrinsic activity of spinel oxide Co₃O₄, while the introduction of Ni creates abundant oxygen vacancies, thus exposing more active sites at the surface and accelerating the OER kinetics. The optimized Ru/Ni-Co₃O₄ nanoparticles possess a low overpotential (290 mV at 10 mA cm⁻²) and excellent stability (only 1% activity decay after 10 h), significantly superior to the state-of-the-art IrO₂ and most OER electrocatalysts reported before. This work provides a new strategy to increase the density of the active sites and generate surface oxygen vacancies simultaneously without destroying the crystallinity/microstructure and use of any additional complicated treatments (such as plasma techniques and multi-step pyrolysis).