Photostable selenium-assisted ZnS nanocomposite with efficient visible light photocatalytic activity

Abstract

Selenium-assisted ZnS nanocomposite has been successfully prepared through a simple soft chemical route and their photocatalytic activity was also investigated for degradation of methylene and rhodamine B dye under ultraviolet and sunlight irradiation. Various surface analysis techniques such as XRD, SEM, TEM, UV-visible, XPS, and photoluminescence were used to analyze the formation of Se/ZnS nanocomposites. XRD studies confirmed the formation of the selenium phase along with ZnS and zinc methacrylate. SEM images showed that ZnS and Se nanoparticles self-aggregated to form three-dimensional spherical nano-assemblies of an average size of about 527 nm. The presence of a different type of defect in Se/ZnS was analyzed from PL spectra. The photocatalytic study revealed the complete degradation of methylene blue in 75 min with a rate constant of 0.073 min−1 under UV light irradiation. In contrast, rhodamine B (RhB) degraded in 90 min with a corresponding rate constant of 0.038 min−1 under the same time duration. Further, this nanocomposite was also efficient under natural sunlight, and almost 85% degradation was achieved after 180 min. Thus, the synergistic effect of strong absorption under UV and visible light source of Se/ZnS nanocomposite minimizes the photogenerated electron-hole pair recombination., which makes them excellent photocatalysts towards the degradation of dyes. Also, this nanocomposite reduced the photo-corrosion under light irradiation and improved photocatalytic stability. In addition, scavenger studies and electron spin resonance in combination with spin trapping technique were used to analyze the contribution of reactive species involved in photocatalysis process.