Embedding microcrystalline SnSe into polyvinylidene fluoride foam: A novel piezoelectric composite for pollutants degradation

Two-dimensional piezoelectric nanomaterials are promising candidates for the piezocatalytic degradation of organic pollutants. However, challenges such as poor recyclability and the risk of secondary pollution must be addressed to enable large-scale applications. Herein, a novel hierarchical porous piezoelectric composite foam was synthesized by embedding microcrystalline SnSe nanoparticles partially onto the wall surfaces of polyvinylidene fluoride (PVDF) matrix. The excellent flexibility and hierarchical pore structure of the composite foam facilitated the capture of weak mechanical energy and provided abundant sites for catalysis. The bi-piezoelectric integration effect, featuring microcrystalline SnSe decoration and PVDF matrix rich in polar β‑phase induced by SnSe, significantly enhanced the piezocatalytic activity. Compared to pure PVDF, the 15   wt% SnSe/PVDF composite foam exhibited superior piezocatalytic activity for various organic pollutants. The degradation rate for Rhodamine B (RhB) dye was enhanced by 10 times, while that for ciprofloxacin (CIP) antibiotic was enhanced by 20 times. The stability and recyclability of composite foam were investigated, and the degradation application of RhB under simulated water flow-driven treatment conditions was visually monitored. The enhancement mechanism of the piezoelectric property of composite foam was clarified through measurements of the dielectric constant and piezoelectric coefficient, complemented by finite element modeling simulation. The degradation intermediates of CIP on 15   wt% SnSe/PVDF composite foam were identified by high-performance liquid chromatography-mass spectrometry. The degradation pathway for CIP was proposed based on a combination of density functional theory calculations and frontier orbit theory.