Synthesis of TiO@Au Composite Catalyst for Methylene Blue Removal.

In this article, HBP-NH₂-modified titania nanowire (TiO)-decorated Au nanoparticles (TiO@Au) were synthesized by one-step method. The role of HBP-NH₂ concentration in the formation of TiO was investigated. The fineness and uniformity of pure TiO were enhanced by absorbed amino groups from amino-terminated hyperbranched polymer (HBP-NH₂). The morphology and crystal structure of TiO and TiO@Au were examined by transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fournier transform infrared (FTIR) spectroscopy. The chemical states of gold, titanium and oxygen were analyzed by X-ray photoelectron spectroscopy (XPS). The results showed that at the concentration of HBP-NH₂ 100 g/L, the mean diameter of TiO was nearly 72 nm and Au nanoparticles were uniformly distributed on the surface of TiO. The presence of Au improved the photocatalytic properties of TiO under UV light irradiation. The Au load was believed to improve the utilization rate of the photoelectron and activated the adsorbed oxygen. The obtained TiO@Au decomposed 99.6% methylene blue (MB) after 300 min when subjected to UV light irradiation. After five cycles of the catalyzing process, the TiO@Au still retained over 90% of its catalytic ability for MB. The Au deposition was found responsible for the high catalytic activity of TiO@Au.