Arming Ru with Oxygen Vacancy Enriched RuO 2 Sub-nanometer Skin Activates Superior Bifunctionality for pH-Universal Overall Water Splitting.

Water electrolysis has been expected to assimilate the renewable yet intermediate energy-derived electricity for green H 2 production. However, current benchmark anodic catalysts of Ir/Ru-based compounds severely suffer from poor dissolution resistance. Herein, we propose an effective modification strategy by arming a sub-nanometer RuO 2 skin with abundant oxygen vacancy to the interconnected Ru clusters/carbon hybrid microsheet (denoted as Ru@V-RuO 2 /C HMS), which can not only inherit the high HER activity of Ru, but more importantly, activate the superior activity towards OER in both acid and alkaline conditions. Outstandingly, it can achieve an ultralow overpotential of 176/201 mV for OER and 46/6 mV for HER to reach 10 mA cm -2 in acidic and alkaline solution, respectively. Inspiringly, the overall water splitting can be driven with an ultrasmall cell voltage of 1.467/1.437 V for 10 mA cm -2 in 0.5 M H 2 SO 4 /1.0 M KOH, respectively. Density functional theory calculations disclose that armoring the oxygen vacancy enriched RuO 2 exoskeleton can cooperatively alter the interfacial electronic structure and make the adsorption behavior of hydrogen and oxygen intermediates much close to the ideal level, thus simultaneously speeding up the hydrogen evolution kinetics and decreasing the energy barrier of oxygen release. This article is protected by copyright. All rights reserved.