Equimolar ZnO-CdS nanocomposite for enhanced photocatalytic performance

Nanocomposite of ZnO-CdS having an equal molar ratio (1:1) of the two components has been synthesized using chemical co-precipitation method, with optimized parameters for efficient photocatalytic properties. A variety of suitable techniques including synchrotron based extended X-ray absorption fine structure (EXAFS) have been used to investigate structural, morphological and optical properties of the nanocomposite. The synthesized nanostructured ZnO-CdS nanocomposite is found to have homogenously distributed crystalline grains of both ZnO and CdS. The uniform distribution of grains and the equal molar ratio of the two components have resulted in excellent optical and photocatalytic performance. The UV-Vis absorption spectrum of nanocomposite shows absorption behavior, extended almost uniformly in the entire UV-visible region, with a red shift in the optical band gap of ZnO, suggestive of efficient photocatalytic ability. The photoluminescence spectrum shows the absorbance in both UV and visible regions, corresponding to the near-band-edge emissions of the ZnO and CdS, respectively. Finally, the photocatalytic performance has been studied in photodegradation of methylene blue dye, showing an enhanced efficiency of almost 99% in 110 min, much higher than that of pristine ZnO, as well as CdS and one of the best reported in the literature.