Electrochemical Evolution of Ru‐Based Polyoxometalates into Si,W‐Codoped RuOx for Acidic Overall Water Splitting

Despite intensive studies over decades, the development of electrocatalysts for acidic water splitting still relies on platinum group metals, especially Pt and Ir, which are scarce, expensive, and poorly sustainable. Because such problems can be alleviated, Ru‐based bifunctional catalysts such as rutile RuO2 have recently emerged. However, RuO2 has a relatively low activity for hydrogen evolution reactions (HER) and low stability for oxygen evolution reactions (OER) under acidic conditions. In this study, the synthesis of a RuOx‐based bifunctional catalyst (RuSiW) for acidic water splitting via the electrochemical evolution from Ru‐based polyoxometalates at cathodic potentials is reported. RuSiW consists of the nanocrystalline RuO2 core and Si,W‐codoped RuOx shell. RuSiW exhibits outstanding HER and OER activity comparable to Pt/C and RuO2, respectively, with high stability. Computational analysis suggests that the codoping of RuOx with W and Si synergistically improves the HER activity of otherwise poor RuO2 by shifting the d‐band center and optimizing atomic configurations beneficial for proper hydrogen adsorption. This study provides insights into the design and synthesis of unprecedented bifunctional electrocatalysts using catalytically inactive and less explored elements, such as Si and W. This study unveils the synthesis of a robust, bifunctional electrocatalyst via the electrochemical evolution of Ru‐based polyoxometalates into Si,W‐codoped RuOx (RuSiW) for efficient acidic water splitting. Exploiting the synergistic effects of Si and W codoping, RuSiW catalyst achieves remarkable activity and stability for acidic hydrogen and oxygen evolution reactions.