Hybridized Nanowires and Cubes: A Novel Architecture of a Heterojunctioned TiO_2/SrTiO_3 Thin Film for Efficient Water Splitting

摘要

A unique morphology of SrTiO_3 nanocubes precipitated on TiO_2 nanowires is successfully synthesized in the form of a thin-film heterojunctioned TiO_2/ SrTiO_3 photocatalyst using facile hydrothermal techniques. The formation mechanisms of the synthesized photocatalysts are meticulously studied and described. Growth of SrTiO_3 single crystal nanocubes (=50 nm in width) on anatase polycrystalline nanowires follows an in situ dissolution-precipitation pathway. This is consonant with the classic LaMer model. By analyzing the results of field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), and UV-vis spectrophotometry, a comprehensive structural and morphological characterization of the photocatalysts is established. FESEM images reveal that the anatase film comprises mainly of nanowires bristles while the tau-sonite film is primarily made up of nanocube aggregations. In comparison to the respective pristine semiconductor photocatalysts, the heterostructured photocatalyst demonstrates the highest efficiency in photocatalytic splitting of water to produce H_2,4.9 times that of TiO_2 and 2.1 times that of SrTiO_3. The enhanced photocatalytic efficiency is largely attributed to the efficient separation of photogenerated charges at heterojunctions of the two dissimilar semiconductors, as well as a negative redox potential shift in the Fermi level.