Photocatalytic performance of electrospun CNT/TiO2 nanofibers in a simulated air purifier under visible light irradiation

The photocatalytic treatment of gaseous benzene under visible light irradiation was developed using electrospun carbon nanotube/titanium dioxide (CNT/TiO₂) nanofibers as visible light active photocatalysts. The CNT/TiO₂ 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/TiO₂ was fixed at 0.05:1 by weight, and the quantity of CNT/TiO₂ loaded in PVP solution varied between 30 and 60 % wt. CNT/TiO₂ nanofibers have high specific surface area (116 m²/g), significantly higher than that of TiO₂ nanofibers (44 m²/g). The photocatalytic performance of the CNT/TiO₂ nanofibers was investigated by decolorization of 1 × 10⁻⁵ M methylene blue (MB) dye (in water solution) and degradation of 100 ppm gaseous benzene under visible light irradiation. The 50-CNT/TiO₂ nanofibers (calcined CNT/TiO₂ nanofibers fabricated from a spinning solution of 50 % wt CNT/TiO₂ based on PVP) had higher MB degradation efficiency (58 %) than did other CNT/TiO₂ nanofibers and pristine TiO₂ nanofibers (15 %) under visible light irradiation. The photocatalytic degradation of gaseous benzene under visible light irradiation on filters made of 50-CNT/TiO₂ nanofibers was carried out in a simulated air purifier system. Similar to MB results, the degradation efficiency of gaseous benzene by 50-CNT/TiO₂ nanofibers (52 %) was higher than by other CNT/TiO₂ nanofibers and pristine TiO₂ nanofibers (18 %). The synergistic effects of the larger surface area and lower band gap energy of CNT/TiO₂ nanofibers were presented as strong adsorption ability and greater visible light adsorption. The CNT/TiO₂ nanofiber prepared in this study has potential for use in air purifiers to improve air treatment efficiency with less energy.