Facile synthesis of MWCNT-WO3 composites with enhanced photocatalytic degradation of methylene blue dye

Multi-walled carbon nanotube-tungsten oxide (MWCNT-WO3) nanocomposites corresponding to different weight ratios of the two composite components MWCNT:WO3 were prepared by using a facile synthesis procedure and tested as photocatalysts activated by UV light for degradation of synthetic methylene blue (MB) solution. The composites were characterized by XRD, TEM, SEM, FTIR, UV–VIS, PL and TGA. The average crystallite size of WO3 calculated from XRD patterns was around 45 nm for all synthesized samples. TEM and SEM images confirmed the attachment of polyhedral WO3 nanoparticles on the MWCNTs surface. TGA results showed an enhanced thermal stability of the MWCNT-WO3 composites with increased content of WO3. Photocatalytic experiments proved that the use of MWCNTs offered a notable increase of the photocatalytic performance of WO3 in degradation of MB dye. The optimum MWCNT-W-7 composite exhibited 87 % MB degradation efficiency. The types of ROS generated by the composites were determined using EPR spectroscopy coupled with spin trapping technique. These results suggested that hydroxyl radicals were the main species involved in the photodegradation process of MB dye.