Abstract
Using P25 as the titanium source and based on a hydrothermal route, we have synthesized CaTiO(3) nanocuboids (NCs) with the width of 0.3-0.5 μm and length of 0.8-1.1 μm, and systematically investigated their growth process. Au nanoparticles (NPs) of 3-7 nm in size were assembled on the surface of CaTiO(3) NCs via a photocatalytic reduction method to achieve excellent Au@CaTiO(3) composite photocatalysts. Various techniques were used to characterize the as-prepared samples, including X-ray powder diffraction (XRD), scanning/transmission electron microscopy (SEM/TEM), diffuse reflectance spectroscopy (UV-vis DRS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Rhodamine B (RhB) in aqueous solution was chosen as the model pollutant to assess the photocatalytic performance of the samples separately under simulated-sunlight, ultraviolet (UV) and visible-light irradiation. Under irradiation of all kinds of light sources, the Au@CaTiO(3) composites, particularly the 4.3%Au@CaTiO(3) composite, exhibit greatly enhanced photocatalytic performance when compared with bare CaTiO(3) NCs. The main roles of Au NPs in the enhanced photocatalytic mechanism of the Au@CaTiO(3) composites manifest in the following aspects: (1) Au NPs act as excellent electron sinks to capture the photoexcited electrons in CaTiO(3), thus leading to an efficient separation of photoexcited electron/hole pairs in CaTiO(3); (2) the electromagnetic field caused by localized surface plasmon resonance (LSPR) of Au NPs could facilitate the generation and separation of electron/hole pairs in CaTiO(3); and (3) the LSPR-induced electrons in Au NPs could take part in the photocatalytic reactions.