Cost-effective efficient materials for dye degradation using non-aqueous sol-gel route.

Abstract

In the present studies, the synthesis of pure ZnO nanoparticles and Mg and S-doped ZnO particles were carried out using a non-aqueous sol-gel method. The synthesized nanoparticles (NPs) are characterized using XRD, FESEM, EDX, FTIR, UV-Vis-DRS, XPS, PL, and BET surface area analysis. X-ray diffraction (XRD) techniques were used to examine the crystallization of ZnO, Mg-ZnO, and S-ZnO samples. The Mg-ZnO and S-ZnO samples exhibit significant c-axis compression and smaller crystallite sizes as compared to undoped ZnO. The optical band gap of Mg-ZnO and S-ZnO NPs were found to be 2.93eV and 2.32eV, respectively, which are lower than that of ZnO NPs (3.05eV). The S-doped ZnO resulted in the homogenous distribution of sulfur ions in the ZnO lattice crystal. XPS analysis revealed that the doped S element was mostly S4+ and S6+. A systematic evaluation has been conducted to assess the influence of several operational parameters, including doped/undoped stoichiometry, solution pH, catalyst dosage, and radical trapping experiment, on the photocatalytic degradation of Rhodamine 6G (Rh 6G) dye. Furthermore, we investigated the photocatalytic degradation activity of ZnO, Mg-ZnO, and S-ZnO samples with aquoues solution of 5ppm Rhodamine 6G (Rh 6G) at room temperature. Results indicated that pure ZnO nanoparticles have the highest photocatalytic degradation rate constant (0.00344min-1), compared to the samples Mg-ZnO (0.00104min-1) and S-ZnO (0.00108min-1) with Rh 6G dye in presence of visible light emitting diode (Vis-LED) source at room temperature. The enhanced visible light photocatalytic activities of pure ZnO NPs were attributed to their superior surface properties (18.30 m2/g) and effective electron-hole separation.