Electronic characterization and photocatalytic properties of CdS/TiO2 semiconductor composite

Titanium dioxide is broadly used as a catalyst for photochemical reactions. In this work, nanometric particles of CdS (a narrow band gap semiconducting material) were used to impregnate TiO2 in order to optimize its photocatalytic properties. CdS/TiO2 semiconductor composites were obtained in 1, 3, 5 and 20 mol% proportion and characterized by differential thermogravimetric analysis (DTG), X-ray diffraction (XRD), laser-induced fluorescence (LIF) and resonance Raman spectroscopy. The results identified the CdS in hexagonal geometry and the TiO2 in anatase form. Resonance Raman spectroscopy data revealed a lattice softening of the TiO2-anatase phase due to electronic interaction between TiO2 and CdS in the CdS/TiO2 catalyst. The effect of modifying the proportion of CdS in the catalyst electronic properties and efficiency was also studied. The photocatalytic activity of the CdS/TiO2 was investigated using artificial UV light for degradation of the textile azo-dye Drimaren red. The photocatalytic analysis revealed better efficiency for the CdS/TiO2 5% composite as compared with other CdS/TiO2 proportions and with TiO2 alone.