Heterojunction-Engineered MgO@rGO/PVDF-HFP Flexible Films for Highly Efficient Piezocatalytic Degradation and Antibacterial Applications

In this work, PVDF-HFP-based piezoelectric composite films incorporating MgO and rGO nanofillers were fabricated via a facile phase-separation method. The influences of filler composition and loading amount on their piezocatalytic and antibacterial performances were systematically investigated. MgO@rGO/PVDF-HFP film (4 wt % of MgO and 4 wt % of rGO) exhibited the best piezocatalytic activity, achieving rapid degradation on RhB, MO, and MB dyes with high efficiencies of 95.88%, 91.42%, and 98.15%, respectively. The dyes were not only decolorized but also further mineralized into inorganic carbon. The composite film also demonstrated excellent antibacterial performance, reaching 100% inhibition against <i>E. coli</i> and <i>S. aureus</i> upon ultrasonication. The superior catalytic behavior is attributed to the formation of the MgO@rGO heterojunction, which optimizes the energy band for the redox reaction, thereby promoting the generation of reactive oxygen species (ROS). Under ultrasonic excitation, the MgO@rGO/PVDF-HFP film produced substantially higher ·O₂^-, ·OH, and H₂O₂ levels than the other films, and ROS-trapping experiments confirmed ·OH and electrons as the primary active species. These enhancements arise from efficient charge transfer across the MgO@rGO interface and chemically induced polarization within the PVDF-HFP matrix, which together strengthen the piezoelectric response. This study demonstrates that constructing heterojunction nanofillers in flexible polymers is an effective strategy to enhance piezocatalysis for environmental purification and antimicrobial applications.