A highly efficient overall water splitting ruthenium-cobalt alloy electrocatalyst across a wide pH range via electronic coupling with carbon dots

Efficient pH-universal overall water splitting electrocatalysts are critical but remain challenging. Herein, a highly efficient, pH-universal overall water-splitting electrocatalyst, was reported by ingeniously controlling the bulk and surface electronic structures of Ru with Co-doping and interfacial incorporation of carbon dots (CDs), respectively. The developed RuCo@CD electrocatalyst present superior hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities with great durability over a wide pH range, achieving a very low overpotential of 51 mV, 11 mV and 67 mV for HER, and 190 mV, 257 mV and 410 mV for OER at 10 mA cm(-2) in 0.5 M H2SO4, 1.0 M KOH and neutral 1.0 M phosphate buffer solution (PBS), respectively. A modified chemical/valence state originating from the strong electronic coupling process among Co, Ru and CDs, is revealed by combined experimental and theoretical results, which contributes to the optimization of water dissociation kinetics. A RuCo alloy was unprecedentedly endowed with efficient and stable bi-functional activities for the first time through electronic coupling with CDs. This reflects the dependence of catalytic activity on chemical/valence states and electronic structures at the atomic level. The work provides a new approach for the design of excellent Ru-based overall water splitting electrocatalysts.