Superior Piezocatalytic Activity and Environmental Adaptability in Micro-Nano-Engineered BaTiO₃/PVDF@Ag Composite Structure

Piezocatalysis, the direct conversion of mechanical energy into chemical reactivity, offers a promising route for sustainable pollutant removal and chemical synthesis. However, practical applications require materials that are able to simultaneously deliver high activity, stability, and ease of recycling. Here, we report a flexible micro-nano-engineered BaTiO₃/PVDF@Ag composite film, whereby {111} BaTiO₃ single-crystal microsheets are embedded in a poly (vinylidene fluoride) (PVDF) matrix and decorated with photo-deposited Ag nanoparticles. This BaTiO₃/PVDF@Ag composite microstructure design endows the optimal composite with outstanding piezocatalytic performance, including a Rhodamine B degradation rate constant of 0.24 min⁻¹, a hydrogen peroxide generation rate of 3520 µmol g⁻¹ h⁻¹, and a CO₂ reduction rate of 535 µmol g⁻¹ h⁻¹, while maintaining its activity over repeated cycles. Systematic structural, spectroscopic, and electrochemical characterization, together with theoretical simulations, reveal that the ferroelectric BaTiO₃ and electroactive β-phase PVDF enhance the local piezoelectric potential under mechanical stimulation, while the Ag nanoparticles act as efficient electron traps and catalytic sites. Interfacial polarization as resulting from the dielectric and conductivity mismatches between the composite components also reduces charge-transfer resistance and thereby accelerates carrier separation and migration. These synergistic effects enable efficient formation of reactive oxygen species, thereby driving high H₂O₂ yields and CO₂ reduction. The mechanically robust film can also be easily recovered and reused, demonstrating a viable route to green, high-performance piezocatalysts for environmental applications.