Direct Hydrothermally Synthesized Novel Z-Scheme Dy3+ Doped ZnO/SnS Nanocomposite for Rapid Photocatalytic Degradation of Organic Contaminants

Abstract

Different concentrations (1, 3 and 5 wt%) of dysprosium (Dy3+)-doped ZnO/SnS (ZSD) nanophotocatalysts using the one-step facile hydrothermal method at 230 ℃ are presented. Their structure, morphological appearance, inclusion of constituent elements, bandgap engineering and luminescent nature are confirmed by the XRD, TEM, XPS, UV-DRS and PL techniques. The photocatalytic activity (PCA) of the prepared nano photocatalysts is studied in the presence of a model pollutant MB under solar light illumination. The degradation kinetics and charge separation mechanism of the ZSD photocatalysts are also presented. Our XRD analysis showed the mixed-phase occurrence of ZnO (hexagonal) and SnS (orthorhombic) from their JCPDS numbers with no additional traces of a doping element, which in turn indicates the purity, substantial crystal structure and high dispersion of the samples. TEM micrographs revealed the appearance of a flake structure and more agglomeration when increasing the dopant concentration. The XPS spectra confirmed the Zn2+, Sn2+, S2−, O2− and Dy3+ oxidation states of the constituent elements along with carbon and nitrogen peaks. The Tauc plots showed a decreasing trend in the optical bandgap, i.e., a redshift due to the loading of Dy3+ ions into Sn2+ ions. The lower recombination rate of photoinduced e−-h+ pairs is noted when increasing the Dy3+ ion content; i.e., the luminescent intensity is suppressed when increasing the concentration of Dy3+ ions. The obtained degradation efficiency of the MB dye using the ZSD3 nano photocatalyst is around 98% for a duration of 120 min under solar light irradiation. The prepared ZSD photocatalyst follows pseudo first-order kinetics, and the evidence for attaining a robust Z-scheme PCA is presented in the form of the charge separation mechanism.

Enhanced Solar Light-Driven Photocatalytic Degradation of Tetracycline Using Fe3+-Doped CdO/ZnS Nanocomposite: Mechanistic Insights and Performance Evaluation

“…This highlights that the primary reactive species responsible for the degradation of TC is the •OH radical. The catalytic removal of TC in the present work is compared with that previously reported in the literature, as shown in Table 1 [49][50][51][52][53][54][55][56][57][58]. The data reveal the enhanced photocatalytic activity of the Fe 3+ -doped CdO/ZnS nanocomposite.…”