Effect of Laser Irradiation of TiO2 Particles and Their Property of Decomposition of Methylene Blue

The decomposition of an organic compound by irradiation with visible light and ultrasound was successfully improved by laser irradiation to TiO2 particles. Micron-size TiO2 powders as raw material in water were irradiated with a laser beam (Nd:YAG, SHG) to obtain nanoparticles. Nanoparticles were examined by scanning electron microscopy (SEM), dynamic light scattering (DLS), X-ray diffraction (XRD), and spectrophotometry. The primary particle size was reduced at high laser fluence. The secondary particle size was reduced to approximately 107 nm from micron size by laser irradiation. The irradiation of laser to anatase TiO 2 did not change the crystal structure. Although laser irradiation to TiO2 reduced the photocatalytic properties for UV light, it realized photocatalytic properties for visible light. Laser irradiation to TiO2 reduced the bandgap. Laser irradiation to TiO2 enhanced ultrasound-induced decomposition of an organic compound.