Electrospun PVDF-TiO2 with tuneable TiO2 crystal phases: synthesis and application in photocatalytic redox reactions

Electrospinning and hydrothermal treatment were employed to fabricate polyvinylidene fluoride (PVDF)-titanium dioxide composite photocatalytic membranes with different anatase, brookite and rutile compositions. The crystal phases were manipulated by adjusting the urea : hydrochloric acid ratio and the concentration of tetrabutyl titanate in the hydrothermal solution, forming either bicrystalline or tricrystalline TiO2. The sample with the highest photoproduction of methane from CO2 (19.8 μmol per gcatalyst per h) showed a low activity in the photooxidation of phenol in aqueous solution under UV irradiation. Based on the results obtained, the crystal phase composition and microstructure of the PVDF-TiO2 greatly influenced the photocatalytic reduction of CO2. Electron spin resonance and XRD indicated a difference in Ti3+ content and this is believed to affect the rate of photodegradation of phenol. This study revealed that small, controlled changes in TiO2 phase and morphology on the electrospun PVDF produced photocatalytic membranes with distinctly different activities.