Synthesis of TiO2NWS@AuNPS Composite Catalyst for Methylene Blue Removal

In this article, HBP-NH2-modified titania nanowire (TiO2NWS)-decorated Au nanoparticles (TiO2NWS@Au-NPS) were synthesized by one-step method. The role of HBP-NH2 concentration in the formation of TiO2NWS was investigated. The fineness and uniformity of pure TiO2NWS were enhanced by absorbed amino groups from amino-terminated hyperbranched polymer (HBP-NH2). The morphology and crystal structure of TiO2NWS and TiO2NWS@Au-NPS 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 TiO2NWS was nearly 72 nm and Au nanoparticles were uniformly distributed on the surface of TiO2NWS. The presence of Au-NPS improved the photocatalytic properties of TiO2NWS under UV light irradiation. The Au load was believed to improve the utilization rate of the photoelectron and activated the adsorbed oxygen. The obtained TiO2NWS@Au-NPS decomposed 99.6% methylene blue (MB) after 300 min when subjected to UV light irradiation. After five cycles of the catalyzing process, the TiO2NWS@Au-NPS still retained over 90% of its catalytic ability for MB. The Au deposition was found responsible for the high catalytic activity of TiO2NWS@Au-NPS.