Simultaneous Structural and Electronic Engineering on Bi- and Rh-co-doped SrTiO3 for Promoting Photocatalytic Water Splitting

Activating metal ion-doped oxides as visible-light-responsive photocatalysts requires intricate structural and electronic engineering, a task with inherent challenges. In this study, we employed a solid (template)-molten (dopants) reaction to synthesize Bi- and Rh-codoped SrTiO₃ (SrTiO₃ : Bi,Rh) particles. Our investigation reveals that SrTiO₃ : Bi,Rh manifests as single-crystalline particles in a core (undoped)/shell (doped) structure. Furthermore, it exhibits a well-stabilized Rh³⁺ energy state for visible-light response without introducing undesirable trapping states. This precisely engineered structure and electronic configuration promoted the generation of high-concentration and long-lived free electrons, as well as facilitated their transfer to cocatalysts for H₂ evolution. Impressively, SrTiO₃ : Bi,Rh achieved an exceptional apparent quantum yield (AQY) of 18.9 % at 420 nm, setting a new benchmark among Rh-doped-based SrTiO₃ materials. Furthermore, when integrated into an all-solid-state Z-Scheme system with Mo-doped BiVO₄ and reduced graphene oxide, SrTiO₃ : Bi,Rh enabled water splitting with an AQY of 7.1 % at 420 nm. This work underscores the significance of simultaneous structural and electronic engineering and introduces the solid-molten reaction as a viable approach for this purpose.