Fabrication of TiO2 mesoporous microspheres sensitized with CdS nanoparticles and application in photodegradation of organic dye

Abstract

TiO2 mesoporous microspheres were prepared by water heating reflux of TiO2 precursors obtained via hydrolysis of tetrabutyl titanate. TiO2 microspheres were printed on FTO glass substrate and sensitized with CdS nanoparticles for forming CdS/TiO2 thin film via a successive ionic layer adsorption and reaction process. TiO2 microspheres and CdS/TiO2 thin film were characterized using field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, N2 adsorption desorption measurements, X-ray photoelectron spectroscopy, and UV–Vis absorption spectra. The results indicated that water heating reflux contribute to the crystallization of TiO2 from the amorphous to anatase phase. TiO2 mesoporous microspheres with higher surface area of 268.53 m2/g were formed during the water heating reflux process. A photoresponsive test suggested that the introduction of CdS improves light utilization of TiO2 mesoporous microspheres and reduces recombination of photogenerated electron–hole pairs. Photocurrent density of TiO2 microspheres sensitized with CdS nanoparticles reached 0.2 mA/cm2 while pure TiO2 only obtained 0.036 mA/cm2. The photodegradation performance of the CdS/TiO2 thin film was further investigated. Photodegradation efficiency of CdS/TiO2 thin film reach about 95% within 120 min due to the synergistic effect of CdS and TiO2 heterostructure. The possible catalytic mechanism was also proposed.