Visible light photocatalysis via nano-composite CdS/TiO2 materials

Abstract

AbstractNano-structured colloidal semiconductors with heterogeneous photocatalytic behavior have drawn considerable attention over the past few years. This is due to their large surface area, high redox potential of the photogenerated charge carriers and selective reduction/oxidation of different class of organic compounds. Nano-structured TiO2 is widely used as a photocatalyst for the effective decomposition of organic compounds in air and water under UV radiation. On the other hand, the development of visible light activated photocatalysis, for utilizing the available solar energy remains a challenge and requires low band gap materials as sensitizer. Among the various inorganic sensitizers, bulk CdS with an Eg of 2.5 eV and an energetically high-lying conduction band has been identified as a potential candidate. This can be coupled with a large band gap semiconductor (TiO2 with Eg ∼ 3.2 eV) for visible light photocatalysis and solar energy conversion. In the CdS sensitized TiO2 nano-composite system, charge injection from the conduction band of the semiconductor sensitizer to that of TiO2 can lead to an efficient and longer charge separation by minimizing electron-hole recombination. In the present paper, we have carried out a systematic synthesis of nano-structured CdS/TiO2 via reverse micelle process. The structural and microstructural characterizations of the as-prepared CdS/TiO2 nano-composites are determined using XRD and SEM-EDS techniques. The visible light assisted photocatalytic performance is monitored by means of degradation of phenol in water.