Controlled fabrication of ordered mesoporous titania/carbon fiber composites with high photoactivity: Synergistic relationship between surface adsorption and photocatalysis

• Carbon fibers (CFs) supported titania with the ordered mesopores.
• Photocatalytic degradation behavior of acid orange 7 is described by L–H kinetics.
• The dependence of the reaction rate on ordered mesoporous titania (OMPT) content.
• Kads and kr in L–H depended on OMPT content, combination from of OMPT and CFs.

Ordered mesoporous TiO2 (OMPT) supported on carbon fibers (OMPT/CFs) were fabricated by supercritical deposition using liquid crystal as soft template. The OMPT/CFs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS) and nitrogen sorptometry, and their photocatalytic activity was studied through the degradation of acid orange 7 (AO7) aqueous solution. The results indicate that OMPT is dispersed on the CFs with crystalline size of 10–20 nm and pore size of 2–5 nm. Although with increasing amount of TiO2 coatings the surface area of OMPT/CFs decreased relative to that of CFs, OMPT/CFs-n (n = 3) (n is the number of precipitation/drying cycles used to prepare the composite), which had the maximum TiO2 content, still possessed a surface areas of 538.6 m2/g because of the mesostructure characteristics of titania. The OMPT/CFs showed high activity in the photodegradation of AO7 in aqueous solution in comparison with P25, pure OMPT and OMPT–CF mixture. Such activity was facilitated by the synergistic relationship between surface adsorption characteristics and photocatalytic potential. Because of the mutual constraint between loading and surface area on the photocatalytic efficiency, the optimal loading of OMPT in OMPT/CFs-2 for AO7 degradation is 15.2 wt%. The photocatalytic behavior could be described in terms of a modified Langmuir–Hinshelwood model.

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