Synthesis and Optical Properties of Sb-Doped CdS Photocatalysts and Their Use in Methylene Blue (MB) Degradation

Abstract

Sb-CdS catalysts with good crystalline structure were prepared by chemical precipitation and hydrothermal method. The results showed that hydrothermal treatment is an effective method to prepare CdS based catalysts of hexagonal structure. Single Sb2S3 catalyst has spherical and Sb doped CdS catalysts have hexagonal structure. Sb doped CdS which is prepared by Na2S with chemical precipitation, has cubic structure. The band gap energies of Sb doped CdS photocatalysts were estimated using UV-visible reflectance spectra to be about the range of 2.35-2.57 eV. In particular, the photoluminescence (PL) spectra show enhancing emission peaks that strongly decrease with a doping Sb where the catalyst was prepared with ethylenediamine (EDA) and thioacetamide (TAA), has shown the lowest luminescence intensity. Photocatalytic degradation of methylene blue was carried out using Sb doped and Sb2S3-CdS binary catalysts under a 400 W medium-pressure mercury lamp of visible light irradiation (lambda>420 nm). Higher photocatalytic degradation was achieved by adding Sb to CdS catalyst with using hydrothermal method and EDA as coordinating agent compare with the other catalysts. In this case the photocatalytic degradation of the Sb-CdS-EDA-TAA photocatalyst after 4 h irradiation time was about 84 %.