Facile synthesis, structural and optical properties of,Au-TiO2 plasmonic nanohybrids for photocatalytic applications

In this study, we conducted the room temperature synthesis of Au-TiO2 plasmonic nanohybrids with Au nanoparticles chemically attached to the TiO2 nanostructures. We systematically examined the effects of modifying the nanostructured TiO2 with Au nanoparticles based on their structural and optical properties. Transmission electron microscopy showed that the Au nanoparticles were uniformly attached to the TiO2 nanostructures. X-ray diffraction analysis confirmed the presence of Au nanoparticles on the TiO2 nanostructures. Ultraviolet-visible diffuse reflectance spectroscopy study of the Au-TiO2 nanostructures detected a peak at 554 nm due to the surface plasmon resonance of the Au nanoparticles. The photoCatalytic efficiency of the AuTiO2 plasmonic nanohybrids increased with the attachment of more Au nanoparticles to TiO2 nanostructures. The superior photodegradation activity of the Au-TiO2 nanohybrids can be attributed to the creation of Schottky junctions and the efficient utilization of sunlight. The as-synthesized Au-TiO2 plasmonic nanohybrids degraded organic dyes comprising methylene blue (MB), methyl orange (MO), a mixture of MO and MB, and 4-nitrophenol in water under sunlight. The most efficient Au-TiO2 plasmonic nanohybrids exhibited degradation efficiencies of 94% with MB, 85% with MO, and 87% with the mixture of MO and MB in only 20 min under irradiation by sunlight. The photocatalytic activity of the Au-TiO2 nanohybrids was 3.3 times greater than that of the pristine TiO2. A mechanism is proposed to explain the superior photocatalytic activity of the Au-TiO2 plasmonic nanohybrids. In this study, we demonstrated a facile method for the development of highly efficient plasmonic photocatalysts.