Structural, optical and photocatalytic study of ZnO and ZnO–ZnS synthesized by chemical method

Zinc oxide (ZnO) and ZnO–ZnS nanocomposite materials have been prepared by simple chemical co-precipitation method. The X-ray diffraction analysis revealed formation of ZnO and ZnO–ZnS crystalline materials. FESEM and HRTEM analyses indicated the formation of flake-like ZnO and sheet-like ZnO–ZnS structures. Energy dispersive X-ray (EDS) study further established formation of ZnO and ZnO–ZnS materials. In the FTIR spectrum the presence of Zn-O symmetric stretching vibration at 442cm−1 and 809cm−1, due to weak vibration of ZnO, while the other peak at 687cm−1 due to Zn-S symmetric bending vibration proved the formation of ZnO–ZnS composite material. Optical absorption spectrum showed that the band gap energy decreased for ZnO–ZnS composite compared to the pure ZnO NPs. The photoluminescence spectral analysis shows that the broad emissions spectrum caused due to several different bands, owing to presence of zinc vacancies, oxygen vacancies, and surface defects. The photocatalytic performance of these samples were tested for degradation of a dye methylene blue under UV light exposure. ZnS–ZnO composite shows the higher dye degradation efficiency (93%) than that of pure ZnO (55%).