tThe multi-walled carbon nanotubes, titania nanotubes, and Pt metal (Pt/TNT-MWCT) hybrids; syn-thesized via hydrothermal-deposition methods, were tested toward photocatalytic degradation ofmethylene blue (MB) dye under visible light ( > 420 nm) in comparison with the binary hybrid Pt/TNTand Pt/graphene photocatalysts. These catalysts were characterized using X-ray diffraction (XRD), UV–visdiffuse reflectance (DRUV–vis), Fourier transform infrared spectroscopy (FTIR), N2sorptiometry, pho-toluminescence (PL) spectroscopy and transmission electron microscopy (TEM) attached with energydispersive X-ray spectroscopy (EDX). DRUV–vis analysis confirmed the enhancement in the absorptionof Pt/TNT following MWCNT incorporation. TEM images showed the coverage of MWCNTs by brookiteTNT that has been substantiated by EDX. The higher photo-activity of Pt/TNT-MWCNT (100% degra-dation in 140 min under visible irradiation) was attributable to the better contact between MWCNTand TNT; exhibited via formation of the Ti O C bond, which promoted the charge separation andelectron transportation. Reduced charge recombination was evidenced for Pt containing samples and afurther reduction was existed following MWCNTs incorporation; as investigated by PL measurements. Theadsorption of MB by MWCNTs played major role in the removal efficiency. On the other hand, Pt/graphenepresented appreciable activity, however, lower than Pt/TNT-MWCNT both in UV and vis light spectralregions due to decreasing the photocatalytic effect of the former than that of the latter. A mechanism forthe MB oxidation was proposed based on the obtained results. |
