Robust Ru‐VO₂ Bifunctional Catalysts for All‐pH Overall Water Splitting

Abstract

Designing robust bifunctional catalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction in all-pH conditions for overall water splitting (OWS) is an effective way to achieve sustainable development. Herein, a composite Ru-VO₂ containing Ru-doped VO₂ and Ru nanoparticles (NPs) is synthesized, and it shows a high OWS performance in full-pH range due to their synergist effect. In particular, the OER mass activities of Ru-VO₂ at 1.53 V (vs RHE) in acidic, alkaline, and PBS solutions are ≈65, 36, and 235 times of commercial RuO₂ in the same conditions. The "Ru-VO₂ || Ru-VO₂ " two-electrode electrolyzer only needs a voltage of 1.515 V (at 10 mA cm^-2 ) in acidic water splitting, which can operate stably for 125 h at 10 mA cm^-2 without significant voltage decay. In situ Raman spectra and in situ differential electrochemical mass spectrometry prove that the OER of Ru-VO₂ in acid follows the adsorption evolution mechanism. Density functional theory calculations further reveal the synergistic effect between Ru NP and Ru-doped VO₂ , which breaks the hydrogen bond network formed by *OH adsorbed on the Ru single-atom site, and thereby significantly enhances the OER activity. This work provides new insights into the design of novel bifunctional pH-universal catalysts for OWS.