Electronic Structure Engineering of Single-Atom Ru Sites via Co-N4 Sites for Bifunctional pH-Universal Water Splitting.
basic_science · Level V
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- Record sourced from PubMed, PMID 35384087.
- Also identified by DOI 10.1002/adma.202110103.
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Abstract
The development of bifunctional water-splitting electrocatalysts that are efficient and stable over a wide range of pH is of great significance but challenging. Here, an atomically dispersed Ru/Co dual-sites catalyst is reported anchored on N-doped carbon (Ru/Co-N-C) for outstanding oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in both acidic and alkaline electrolytes. The Ru/Co-N-C catalyst requires the overpotential of only 13 and 23 mV for HER, 232 and 247 mV for OER to deliver a current density of 10 mA cm<sub>geo</sub> <sup>-2</sup> in 0.5 m H<sub>2</sub> SO<sub>4</sub> and 1 m KOH, respectively, outperforming benchmark catalysts Pt/C and RuO<sub>2</sub> . Theoretical calculations reveal that the introduction of Co-N4 sites into Ru/Co-N-C efficiently modify the electronic structure of Ru by enlarging Ru-O covalency and increasing Ru electron density, which in turn optimize the bonding strength between oxygen/hydrogen intermediate species with Ru sites, thereby enhancing OER and HER performance. Furthermore, the incorporation of Co-N4 sites induces electron redistribution around Ru-N4, thus enhancing corrosion-resistance of Ru/Co-N-C during acid and alkaline electrolysis. The Ru/Co-N-C has been applied in a proton exchange membrane water electrolyzer and steady operation is demonstrated at a high current density of 450 mA cm<sub>geo</sub> <sup>-2</sup> for 330 h.