Fabrication of mesoporous WO3-SBA-15 catalysts and enhanced photocatalytic degradation of harmful dyes

Abstract

Mesoporous SBA-15 and x% WO3-SBA-15 (X = 2.7 %, 5.5 %, 8.3 % and 11.1 %) catalysts were synthesized by hydrothermal in-situ method. All the synthesized catalysts were subjected to different analytical techniques such as XRD, FT-IR, BET, XPS, FE-SEM, EDX, HR-TEM, DRS-UV and PL. The HR-TEM images showed that WO3 species were highly dispersed in the uniform pore channels of SBA-15. Photo decolorization activity of the bare and composite catalysts measured in the degradation of harmful dyes such as rhodamine B (RhB), methylene blue (MB) and crystal violet (CV) under UV, visible and solar light irradiations. Among the catalysts, 5.5 % WO3-SBA-15 exhibited the highest photocatalytic activity (81 %, 90 %, and 77 %) towards the degradation of RhB, MB and CV dyes under visible light irradiation. TOC and COD studies indicated that the three dyes chosen for the present study were all degraded to large extent. The trapping experiment confirmed that the major species responsible for the photocatalytic degradation of different dyes over 5.5 % WO3-SBA-15 catalysts were found to be h+ and O2−. The stability of the most active catalysts 5.5 % WO3-SBA-15, was determined by the recyclability test. A suitable mechanism was proposed based on experimental evidence.