Preparation of RhOx/TiO2 with Pt cocatalyst effective for photocatalytic alcohol dehydrogenation under irradiation of visible light

Abstract

Photocatalytic alcohol dehydrogenation is a promising technique for the simultaneous production of hydrogen (H₂) and carbonyl compounds. In this study, titanium(IV) oxide (TiO₂) photocatalysts co-loaded with rhodium oxide (RhO_x) and platinum (Pt) particles were successfully prepared via a multi-step process involving the equilibrium adsorption of Rh ions, post-calcination, and Pt colloid impregnation. In the resulting system, RhO_x acts as a visible-light sensitizer, while Pt serves as the hydrogen evolution co-catalyst. A series of RhO_x/TiO₂–Pt samples were synthesized by systematically varying the calcination temperature of the RhO_x/TiO₂ precursor prior to Pt loading. These materials were then evaluated for photocatalytic alcohol dehydrogenation under visible light irradiation. The effects of calcination temperature on the electronic states and light absorption characteristics of the Rh species were investigated, along with their influence on photocatalytic activity. The RhO_x/TiO₂–Pt photocatalysts exhibited efficient dehydrogenation of various alcohols. In particular, benzyl alcohol was selectively converted to benzaldehyde and H₂ in a stoichiometric ratio, with no over-oxidation observed. This work demonstrates a novel strategy for coupling oxidative organic synthesis with hydrogen production under visible light, offering new insights into photocatalyst design for sustainable energy and chemical synthesis.