Photocatalytic Efficiency Improvement of Porous TiO2 Immobilized by a Pd-Te Complex for H2 Production by Water Splitting

Four photocatalysts solids were designed using a new Pd−Te complex, [Pd₂(μ-TePh)₂(bipy)₂](PF₆)₂, immobilized over titania to improve its solar energy harvesting ability for enhancing H₂ production by water splitting under sunlight (300 W Xe/Hg lamp). Firstly, the photocatalytic performance for H₂ production of the porous TiO₂ supports (m-TiO₂), synthesized with varying textural properties and anatase/rutile contents, were compared. Furthermore, cyclic voltammetry measurements revealed that the Pd−Te complex can catalyze protons to hydrogen under weak acidic conditions. Then, different wt % concentrations of the complex were immobilized over the m-TiO₂ of the greatest performance and also over Degussa P25 (commercial titania) for photocatalytic comparison. Among the newly designed photocatalysts, the one containing only 4 wt% of Pd−Te complex over m-TiO₂ showed the greatest hydrogen production (3631 μmol g⁻¹ h⁻¹), which is 69 times greater than that of the pure m-TiO₂ and 378 times higher than that of the pure Pd−Te complex. These results suggested the crucial role of the Pd−Te complex when combined with m-TiO₂, promoting greater photocatalytic performance compared to the pure support. This outcome inspires an extensive investigation of metal complexes combined with semiconductors to improve their ability for photocatalytic H₂ production by water splitting under sunlight.