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

Spinel oxides Co 3 O 4 with mixed valence cations Co 2+ and Co 3+ make it possible to improve the catalytic activity by regulating the distribution of cations via additional doping. Controllable synthesis of nanosized Co 3 O 4 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 Co 3 O 4 nanoparticles (Ru/Ni-Co 3 O 4 ) 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 Co 3 O 4 , 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-Co 3 O 4 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 IrO 2 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). Ru and Ni co-doped Co 3 O 4 with improved OER activity were synthesized by a one-step hydrothermal method. Ru doping increases the intrinsic activity, while Ni doping creates more oxygen vacancies and exposes more active sites.