Piezo-photocatalytic flexible PAN/TiO2 composite nanofibers for environmental remediation.

Mechanical vibrations and solar energy are ubiquitous in the environment. Hereon, we report the synergic enhancement of the oxidation by simultaneously harvesting solar and mechanical vibrations through flexible piezo and photocatalytic composite nanofiber mats. Surface enriched titanium dioxide nanoparticles incorporated in polyacrylonitrile (PAN/TiO2) nanofibers were synthesized using a single pot electrospinning process with well-defined fiber diameters with widely tunable loading density. By incorporating photocatalytic TiO2 in flexible piezoelectric PAN nanofiber support, piezoelectric fields generated under the mechanical deformation promote the separation of the photogenerated electrons and holes to accelerate oxidation of pollutants. Our results demonstrated that the catalytic activity of PAN/TiO2 nanofibers in photodegradation of Rhodamine B (RhB) can be greatly enhanced by environmental vibration-induced piezoelectricity of PAN nanofibers, with a maximum enhancement factor of ~2.5. The working mechanism for the enhanced photocatalytic activity of PAN/TiO2 nanofibers by the mechanical vibrations were attributed to the piezoelectric effect of PAN nanofibers, which could efficiently promote the separation of the photogenerated electrons and holes in the TiO2 nanoparticles. We believe the approach to enhancing the catalytic activity of mat can make full use of the polymer properties and natural energy, and it also can be extended to other composite polymer/semiconductor systems.