Quantum dot sensitized electrospun mesoporous titanium dioxide hollow nanofibers for photocatalytic applications

Abstract

In this work, mesoporous, hollow TiO₂ nanofibers were fabricated by a coaxial electrospinning technique for the photocatalytic degradation of para-nitrophenol (4-NP), a well-known model water pollutant dye. The as-synthesized hollow nanofibers were sensitized by cadmium sulphide (CdS) quantum dots (QDs) through successive ion layer adsorption and reaction (SILAR) method for different deposition cycles. The CdS QDs loaded hollow TiO₂ nanofibers (TiO₂/CdS) harvest catalytic spots at the QDs and TiO₂ interface which helps in enhanced exciton separation. The hollow and porous TiO₂/CdS photocatalyst enhances absorption of UV and visible light due to presence of CdS QDs on the nanofiber surfaces. The resultant CdS QDs synthesized hollow TiO₂ nanofibers exhibit excellent photocatalytic activity as shown with the degradation of 4-NP dye in aqueous medium. The photocatalytic degradation study was probed spectrophotometrically by measuring the absorbance of the degraded 4-NP solution using a UV-Vis absorption spectrophotometer. The effect of CdS QDs deposition cycles on dye degradation performance was also studied for TiO₂/CdS nanofibers. TiO₂/CdS photocatalyst for 3 SILAR deposition cycles was found to be ∼3 times more efficient than hollow TiO₂ nanofibers and ∼8 times effective than the solid nanofibers. These nanofibers are reusable and their nanostructures do not change after repetitive usage. Such pristine and QDs sensitized hollow TiO₂ nanofibers are thus a promising platform for the development of photocatalytic wastewater treatment and other applications such as photocatalytic water splitting, sensors, Li-ion batteries, and supercapacitor electrodes.