Effect of annealing on luminescence and photocatalytic activity of ZnS nanocrystals under UV light irradiation

Zinc sulfide (ZnS) nanocrystals were prepared at a large-scale via precipitation of Zn2+ ions water solution with gaseous hydrogen sulfide, H2S. The effect of annealing time on the ZnS phase structure, morphology, and optical properties was investigated in detail by XRD, SEM, UV-vis, and photoluminescence (PL) spectroscopy. It was observed that pristine ZnS possessed a pure cubic phase structure and an increase in annealing time resulted in a phase mixture with increased content of wurtzite phase structure. Moreover, the crystallinity of the prepared samples, as well as PL intensities, increased with increasing annealing time. Photocatalytic activities of the pristine ZnS annealed at different time intervals were evaluated by the means of methyl violet 2B (MV 2B) degradation under UV LED illumination wavelengths at λmax~ 343 nm and 365 nm. It was observed that the photocatalytic activities of the annealed ZnS samples increased with increasing annealing time. The improved photocatalytic performance can be attributed to the improved crystallinity of annealed ZnS samples. © 2021 TANGER Ltd., Ostrava.Ministry of Education, Youth and Sports of the Czech RepublicMinistry of Education, Youth & Sports - Czech Republic [LTT20010]; Operational Program Research and Development for InnovationsEuropean Commission; European Regional Development Fund (ERDF)European Commission; national budget of Czech Republic, within the framework of project CPS - strengthening research capacity [CZ.1.05/2.1.00/19.0409]; Internal Grant Agency of Tomas Bata University in Zlin [IGA/CPS/2017/007]; Ministry of Education, Youth and Sports of the Czech Republic - Program NPU I [LO1504]IGA/CPS/2017/007; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: LTT20010; European Regional Development Fund, ERDF: CZ.1.05/2.1.00/19.040