Boosting photocatalytic removal of organic pollutants through enhanced piezoelectricity in free-standing nanofibril pyridyl-functionalized conjugated microporous polymer/poly(vinylidene fluoride–trifluoroethylene) hybrids

Abstract

Subjected to mechanical stimuli, a piezo-induced built-in electric field is favorable for promoting the catalytic performance of piezo-photocatalysts via effectively separating the excitons. However, the exact correlation between the electronic structure and catalytic properties of piezo-photocatalysts is still ambiguous. Conjugated microporous polymers (CMPs) with delocalized π-conjugation bonds are a unique class of photocatalytic materials, which exhibit intramolecular transport channels for electron transfer and could be further enhanced by a built-in electric field during photocatalysis. Herein, novel piezo-photocatalytic electrospun hybrid fiber films were prepared, which endow piezoelectric poly(vinylidene fluoride-co-trifluoroethylene) (PVDF–TrFE) with the high photocatalytic activity of a pyridine-based CMP (PCMP). The compatibility of these two components was enhanced via silane modification of the PCMP (m-PCMP). Hybrids of m-PCMP 50 wt%/PVDF–TrFE showed an excellent photo-degradation efficiency (97%) towards rhodamine B (RhB) with a high pseudo-first-order kinetic constant (k) of 0.0289 min⁻¹ which is comparable to that of the neat m-PCMP (0.0304 min⁻¹) and nearly 15 times higher compared to that of pure PVDF–TrFE (0.0019 min⁻¹). The excellent catalytic performance was attributed to the synergetic effect, where the addition of the m-PCMP enhanced the piezo-response of PVDF–TrFE, and the piezo-potential of PVDF–TrFE regulated the energy band of m-PCMP, favoring the redox reactions to generate reactive oxygen species (ROS) for degrading RhB. The present study proposes a new paradigm for highly active piezo-photocatalysts in terms of tuning the electronic structure and interpreting the structure-to-property correlation.