Three-dimensional BNT/PVDF composite foam with a hierarchical pore structure for efficient piezo-photocatalysis

Piezoelectric semiconductor nanomaterials have been intensively developed for piezo-photocatalysis, in which the built-in electric field generated by piezoelectricity can accelerate the seperation and transfer of photogenerated carriers. However, the challenges of poor recyclability and secondary pollution must be solved for large-scale applications. In this study, a three-dimensional porous poly(vinylidene difluoride) (PVDF) composite foam containing piezoelectric semiconductor Bi 0.5 Na 0.5 TiO 3 (BNT) nanofibers are fabricated. The BNT nanofibers prepared by electrospinning exhibit excellent piezoelectric activity, strong photoexcited response, and low charge transfer resistance. The fabricated BNT/PVDF composite foams display favorable flexibility and hierarchical pore structure, which can easily deform to construct a built-in electric field via bi-piezoelectric integration and owns abundant active sites for catalytic reactions. The PVDF matrix has a dominant electroactive β-phase, responsible for its high piezoelectricity. As a result, the BNT/PVDF composite foam exhibits strong piezo-photocatalytic activity. The degradation of highly-concentrated RhB solution ( C 0 = 50 mg/L) reaches 90.8% within 180 min. This work provides a feasible piezo-photocatalytic material for large-scale applications. • BNT nanofibers show high piezoelectricity and strong photoresponse. • BNT/PVDF foams show favorable flexibility and hierarchical pore structure. • High-concentration RhB (50 mg/L) solution is effectively degraded.