The photocatalytic treatment of gaseous benzene under visible light irradiation was developed using electrospun carbon nanotube/titanium dioxide (CNT/TiO) nanofibers as visible light active photocatalysts. The CNT/TiO nanofibers were fabricated by electrospinning CNT/poly(vinyl pyrrolidone) (PVP) solution followed by the removal of PVP by calcination at 450 °C. The molar ratio of CNT/TiO was fixed at 0.05:1 by weight, and the quantity of CNT/TiO loaded in PVP solution varied between 30 and 60 % wt. CNT/TiO nanofibers have high specific surface area (116 m/g), significantly higher than that of TiO nanofibers (44 m/g). The photocatalytic performance of the CNT/TiO nanofibers was investigated by decolorization of 1 × 10 M methylene blue (MB) dye (in water solution) and degradation of 100 ppm gaseous benzene under visible light irradiation. The 50-CNT/TiO nanofibers (calcined CNT/TiO nanofibers fabricated from a spinning solution of 50 % wt CNT/TiO based on PVP) had higher MB degradation efficiency (58 %) than did other CNT/TiO nanofibers and pristine TiO nanofibers (15 %) under visible light irradiation. The photocatalytic degradation of gaseous benzene under visible light irradiation on filters made of 50-CNT/TiO nanofibers was carried out in a simulated air purifier system. Similar to MB results, the degradation efficiency of gaseous benzene by 50-CNT/TiO nanofibers (52 %) was higher than by other CNT/TiO nanofibers and pristine TiO nanofibers (18 %). The synergistic effects of the larger surface area and lower band gap energy of CNT/TiO nanofibers were presented as strong adsorption ability and greater visible light adsorption. The CNT/TiO nanofiber prepared in this study has potential for use in air purifiers to improve air treatment efficiency with less energy.

Photocatalytic activity of TiO 2 nanoparticles was successfully enhanced by addition of multiwall carbon nanotubes (MWCNT) to make CNT/TiO 2 nanocomposites by sol-gel method at ambient temperature. CNT treated by HNO 3 : H 2 SO 4 treatment (1 : 3 v/v) was mixed with TiO 2 nanoparticles at various molar ratios and calcination temperatures. The optimal molar ratio of CNT : TiO 2 was found at 0.05 : 1 by weight. The optimal calcination condition was 400 ∘ C for 3 h. From the results, the photocatalytic activities of CNT/TiO 2 nanocomposites were determined by the decolorization of 1 × 10 −5 M methylene blue (MB) under visible light. CNT/TiO 2 nanocomposites could enhance the photocatalytic activity and showed faster for the degradation of MB with only 90 min. The degradation efficiency of the MB solution with CNT/TiO 2 nanocomposite achieved 70% which was higher than that with pristine TiO 2 (22%). This could be explained that CNT prevents TiO 2 from its agglomeration which could further enhance electron transfer in the composites. In addition, CNT/TiO 2 nanocomposites had high specific surface area (202 m 2 /g) which is very promising for utilization as a photocatalyst for environmental applications.