Co-doped RuO2 nanoparticles with enhanced catalytic activity and stability for the oxygen evolution reaction

Abstract

Efficient and durable electrocatalysts for the oxygen evolution reaction (OER) play an important role in the use of hydrogen energy. Rutile RuO₂, despite being considered as an advanced electrocatalyst for the OER, performs poorly in stability due to its easy oxidative dissolution at very positive (oxidizing) potentials. Herein, we report a type of Co-doped RuO₂ nanoparticle for boosting OER catalytic activity and stability in alkaline solutions. The replacement of Ru by Co atoms with a lower ionic valence and smaller electronegativity can promote the generation of O vacancies and increase the electron density around Ru, thus enhancing the adsorption of oxygen species and inhibiting the peroxidative dissolution of RuO₂ during the OER process. It was found that Ru_0.95Co_0.05O_y exhibited excellent OER performance with overpotentials as low as 217 mV at 10 mA cm⁻² and 290 mV at 100 mA cm⁻² in 1 M KOH, as well as outstanding stability in continuous testing for 50 h at a current density of 100 mA cm⁻², and nearly no significant degradation after the accelerated durability test of 2000 cycles.