Green synthesis of Pt-doped TiO2 nanocrystals with exposed (001) facets and mesoscopic void space for photo-splitting of water under solar irradiation

Abstract

We report a non-trivial facile chemical approach using ionic liquid ([bmim][Cl]) as a porogen for the synthesis of (001) faceted TiO₂ nanocrystals having mesoscopic void space. This faceted TiO₂ nanomaterial has been doped with Pt nanoclusters through chemical impregnation. The resulting Pt-doped TiO₂ nanomaterials are thoroughly characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), ultra high resolution transmission electron microscopy (UHR-TEM), energy dispersive X-ray spectrometry (EDX), UV-vis diffuse reflection spectroscopy (DRS) and N₂ sorption studies. These Pt/TiO₂ nanocrystals with (001) exposed facets are employed as efficient and benign catalysts for hydrogen production from pure water and methanol–water systems under one AM 1.5G sunlight illumination. The effect of platinum loading and methanol–water ratio on the photocatalytic activity of the faceted TiO₂ nanocrystals are investigated and it is found that hydrogen evolution rates have been enhanced significantly upon Pt loading. Under optimized reaction conditions the highest photocatalytic activity of 11.2 mmol h⁻¹ g⁻¹ has been achieved over ca. 1.0 wt% Pt loaded Pt/TiO₂ nanocrystals with (001) exposed facets, which is one of the highest hydrogen evolution rates over the noble metal/TiO₂ system reported to date in the literature.