Poly(3,4-ethylenedioxythiophene) (PEDOT) infused TiO2 nanofibers: the role of hole transport layer in photocatalytic degradation of phenazopyridine as a pharmaceutical contaminant

Abstract

Pharmaceuticals and personal care products are commonly discarded into environmental waters through sewers with human waste or by direct disposal causing serious contamination. Photocatalytic degradation of phenazopyridine (PAP) as a model pharmaceutical contaminant was investigated using TiO₂ nanofibers and hybrid PEDOT infused TiO₂ nanofibers. A novel material of PEDOT infused TiO₂ nanofibers was fabricated via electrospinning and calcination to form TiO₂ followed by the introduction of PEDOT using vapor phase polymerization. By changing the calcination temperature, the phase composition in TiO₂ nanofibers can be adjusted to pure anatase phase, mixed phase and pure rutile phase. The photocatalytic activities of TiO₂ nanofibers before and after PEDOT polymerization were measured by monitoring the decreasing concentration of PAP in aqueous solution under UV illumination using UV-Vis absorption spectroscopy. PEDOT infused TiO₂ nanofibers showed an improved photocatalytic performance compared to their non-PEDOT infused counterparts for the degradation of PAP. This improvement can be attributed to the introduction of hole transport layer of PEDOT leading to an enhanced hole transfer from the TiO₂ nanofibers to PEDOT. PEDOT infused rutile nanofiber has the most degradation enhancement (125%) compared to other two types of fibers (70% for PEDOT infused anatase & 30% for PEDOT infused mixed-phase).