Hydrothermal synthesis of rhodium-doped barium titanate nanocrystals for enhanced photocatalytic hydrogen evolution under visible light

Rhodium-doped barium titanate (BaTiO3:Rh) nanocrystals were prepared by hydrothermal (HT) method followed by post-heating, and examined as photocatalysts for H-2 evolution from an aqueous methanol solution under visible light (lambda > 420 nm). The photocatalytic activity was dependent on synthetic parameters such as precursor ratio and using precursor materials, post-heating conditions, which have influence on crystallinity, compositional homogeneity and the generation of Ba defects in BaTiO3:Rh, as well as the oxidation state of Rh in the material. Experimental results highlighted that suppressing the generation of Ba defects during the preparation process and improving the crystallinity both contributed to higher photocatalytic activity. The most active material prepared by the HT method outperformed similar analogues prepared by the polymerized complex method and a conventional solid state reaction method.