Activation of hydrogen-evolution reactivity in an Rh-doped SrTiO3 photocatalyst under visible-light irradiation by loading with controlled platinum nanoclusters

Rhodium-doped strontium titanate (SrTiO3:Rh)-based photocatalysts have long been studied because they can produce hydrogen (H-2) from visible light and water in Z-scheme water-splitting systems. However, the H-2-evolution reaction (HER) of SrTiO3:Rh is the rate-limiting step in such a system, so further improvement of the HER activity of SrTiO3:Rh is desired to enhance Z-scheme water splitting. In this study, we synthesize hydrophilic similar to 1 nm platinum nanoclusters (Pt NCs) using a ligand-exchange method while maintaining the geometric structure of the corresponding hydrophobic similar to 1 nm Pt NC, and we load the monodispersed Pt NCs onto SrTiO3:Rh. The Pt NC-loaded SrTiO3:Rh exhibits HER activity that is 30% higher than that of the Pt cocatalyst-loaded SrTiO3:Rh prepared using the conventional photodeposition method. This work also demonstrates that Z-scheme water splitting proceeds stoichiometrically using the Pt NC-loaded SrTiO3:Rh as the H-2-evolution photocatalyst, bismuth vanadate as an oxygen-evolution photocatalyst, and Fe2+ as a mediator.