Observation of catalytic properties of CdS–ZnO composite nanorods synthesized by aqueous chemical growth technique

We have synthesized the nanorods of CdS–ZnO composite by chemical method and have investigated their structure, optical and electrical properties by suitable techniques. The X-rays diffraction results prove the co-existence of CdS and ZnO in usual hexagonal structure and no peak corresponding to any intermediate phase has been identified. The above observation has been confirmed by micro-Raman study. The photo-current action spectra of CdS–ZnO nanorods show a significant enhancement of the photo-current due to visible sensitization by surface CdS layer. In an attempt to explore the catalytic activity of CdS–ZnO, the photodegradation of 3,4-dihydroxy benzoic acid has been investigated under visible irradiation from a halogen lamp. The concentration of aqueous solution of 3,4-dihydroxy benzoic acid decreases with increase in the irradiation time which is attributed to photodegradation of the benzoic acid. A possible mechanism for the redox reactions responsible for degradation of the benzoic acid has been suggested.