Fabrication and characterization of an immobilized titanium dioxide (TiO2) nanofiber photocatalyst

Abstract

Photoactive titanium dioxide (TiO2) solids are known to mineralize a variety of organic pollutants into carbon dioxide. TiO2 solids with dimensions in nanometre have shown enhanced catalytic performance due to a large surface to volume ratio. Nano-sized TiO2 have been studied for their catalytic performance either as suspended particle or immobilized coating. From an engineering and economic perspective, immobilized TiO2 nanocatalysts are preferred in variety of applications. However, past studies have shown that using immobilized nano-sized TiO2 is associated with practical constrains of limited stability and lower catalytic performance. Hence, the objective of the present study is to fabricate an immobilized form of TiO2 catalyst with photocatalytic efficiency comparable with nanoparticles slurry, but without the associated practical constrains. An immobilized TiO2 catalyst was prepared from depositing TiO2 nanofibers onto a chemically treated metal support by sol-gel-electrospinning. The fabricated forms were thermally treated to obtain catalytic immobilized TiO2 nanofibers. The effects of varying the parameters of the electrospinning fabrication process on the diameter of the TiO2 nanofibers were also studied. The formation of smaller diameter TiO2 nanofibers was favoured under a large potential gradient and low infusion rate. The fabricated TiO2 nanofibers, with predominantly an anatase crystal structure and a mean diameter of 54.0 ±11.5 nm, were 30-50% lower than the literature values. Improved stability of the immobilized catalyst was observed using a surface-treated metal support. The catalytic performance of the immobilized TiO2 nanofibers for the photocatalysis of aqueous phenol (a toxic water pollutant) was significant and comparable to that of commercially available 5nm TiO2 nanoparticles. Thus, the study reported a novel fabricated form of immobilized TiO2 photocatalyst with comparable performance but lesser practical constraints compared to nanoparticles.