Polyvinylidene Fluoride/ZnSnO₃ Nanocube/Co₃O₄ Nanoparticle Thermoplastic Composites for Ultrasound-Assisted Piezo-Catalytic Dye Degradation

This work reports a facile, easily retrievable (from treated water), environmentally friendly, ultrasound-assisted piezocatalyst device exhibiting higher reaction kinetics and the lowest degradation time for dyes using a thermoplastic piezocomposite (polyvinylidene-fluoride (PVDF)-zinc stannate (ZnSnO3)-cobalt oxide (Co3O4)). The composite mold (PZC) comprises of hydrothermally grown ZnSnO3 nanocubes interspersed into the PVDF matrix and decorated with Co3O4 nanoparticles by a simple blending and hot molding technique. The orthorhombic structure of ZnSnO3, and β-PVDF were confirmed by XRD, while SEM and FESEM provided a detailed investigation of the composite's morphology. The mold exhibits excellent stability against applied ultrasonic stress without release of ZnSnO3 and Co3O4 particles into treated water and degrades rhodamine B (RhB), methylene blue (MB), and a 1:1 mixture of both dye solutions (RMB) with 100% efficiency within 20 min, which is the fastest time reported so far for piezocatalysis-based dye degradation studies. This enhanced performance is attributed to the synergistic catalytic effect of PVDF in the presence of ZnSnO3 and Co3O4, where ZnSnO3 enhances the polarizability of PVDF, and Co3O4 improves the transport of charge carriers to the surface of the mold for efficient redox reactions. Scavenger testing was performed to confirm the catalytic nature of ultrasonic stress induced dye degradation. Reusability tests revealed 100% efficiency for six consecutive trials. The strategy outlined here can be used for the degradation of a wide variety of complex dyes found in industrial effluents for environmental remediation.