Graphene oxide based Pt-TiO2 photocatalyst: ultrasound assisted synthesis, characterization and catalytic efficiency

An ultrasound-assisted method was used for synthesizing nanosized Pt-graphene oxide (GO)-TiO₂ photocatalyst. The Pt-GO-TiO₂ nanoparticles were characterized by diffused reflectance spectroscopy, X-ray diffraction, N₂ BET adsorption-desorption measurements, atomic force microscopy and transmission electron microscopy. The photocatalytic and sonophotocatalytic degradation of a commonly used anionic surfactant, dodecylbenzenesulfonate (DBS), in aqueous solution was carried out using Pt-GO-TiO₂ nanoparticles in order to evaluate the photocatalytic efficiency. For comparison purpose, sonolytic degradation of DBS was carried out. The Pt-GO-TiO₂ catalyst degraded DBS at a higher rate than P-25 (TiO₂), prepared TiO₂ or GO-TiO₂ photocatalysts. The mineralization of DBS was enhanced by a factor of 3 using Pt-GO-TiO₂ compared to the P-25 (TiO₂). In the presence of GO, an enhanced rate of DBS oxidation was observed and, when doped with platinum, mineralization of DBS was further enhanced. The Pt-GO-TiO₂ catalyst also showed a considerable amount of degradation of DBS under visible light irradiation. The initial solution pH had an effect on the rate of photocatalytic oxidation of DBS, whereas no such effect of initial pH was observed in the sonochemical or sonophotocatalytic oxidation of DBS. The intermediate products formed during the degradation of DBS were monitored using electrospray mass spectrometry. The ability of GO to serve as a solid support to anchor platinum particles on GO-TiO₂ is useful in developing new photocatalysts.