Polyporous PVDF/TiO2 photocatalytic composites for photocatalyst fixation, recycle, and repair

An investigation into photocatalysts mainly focuses on inorganic powders, and their fixation, recycle, and repair in an open and flowing environment remains a problem. Herein, the photocatalytic property of polyvinylidene fluoride (PVDF) is utilized to solve this problem. It can be facilely recycled and repaired because of the form of membrane, and porous structure ensures its sufficient contact with pollutants. In addition, its photocatalytic activity can be effectively modified by compositing TiO 2 nanopowder, which performs better photocatalytic activity than equivalent content TiO 2 powder, originated from the enhanced separation efficiency of electron and hole resulting from the extra driving force maybe generated by PVDF's ferroelectric spontaneous polarization and heterojunction structure, which reduces the recombination of charge carriers. In addition, the pore structure with large density and small size provides more reaction area for the composite structure, which also benefits for the enhancement of photocatalytic activities. Tight combination between PVDF and TiO 2 guarantees the stable activity of the composites under flowing environment, and so PVDF/TiO 2 composite can sustain its initial photocatalytic activity after at least 10 times cycles. More importantly, when the membrane is damaged, it can be easily repaired by the cost of a small quantity of solvent and can maintain its initial photocatalytic activity. This work would promote the understanding of physical mechanisms of enhanced photocatalytic activities, and recycle and repair properties in PVDF- x TiO 2 composites.