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.