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

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2022-10, Vol.1 (41), p.15367-15376
• Main Authors: Meng, Nan, Zhang, Yu, Liu, Yongsheng, Shi, Yu, Jiang, Ruyu, Wu, Jiyue, Liao, Yaozu
• Format: Article
• Language: English
• Subjects: Catalytic activity; Conjugation; Electric fields; Electron transfer; Electronic structure; Energy bands; Excitons; Fluorides; Photocatalysis; Photocatalysts; Photodegradation; Piezoelectricity; Pollutants; Redox reactions; Rhodamine; Vinylidene; Vinylidene fluoride
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/d2tc03288k

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. Nanofibril m-PCMP/PVDF-TrFE with an enhanced piezo-response of PVDF-TrFE and a tilted energy band of m-PCMP showed superb performance of piezo-photocatalytic dye degradation.