In this work, we developed a novel piezoelectrically coupled photocatalytic film fuel cell (PFC) system aimed at synergistically degrading organic pollutants. The PFC consisted of dual heterojunctions; an anode composed of 2D polyvinylidenefluoride-co-hexafluoropropylene (PVDF–HFP) supported 3D flower-like photocatalyst MoS₂–rGO/ZnO@PVDF–HFP heterojunctions and a cathode composed of BiOBr/g-C₃N₄@PVDF–HFP heterojunctions. Our results demonstrated that the degradation efficiency of tetracycline hydrochloride (TC) in the piezoelectrically enhanced PFC was significantly higher compared to photocatalysis alone, with a 2.9-fold increase at the cathode (93.41%) and a 3.7-fold increase at the anode (91.46%). Similarly, the total organic carbon (TOC) removal rates reached up to 85.61% and 76.24%, respectively. The work revealed that the piezoelectric field effect played a crucial role in enhancing the degradation efficiency of the PFC, while the built-in electric field facilitated heterojunction contact surface formation, thereby accelerating electron mass transfer and suppressing photogenerated carriers' recombination rate. To gain insights into the photocatalytic degradation mechanism and potential intermediate pathways, we employed electron paramagnetic resonance (EPR) characterization and high-performance liquid chromatography tandem mass spectrometry (HPLC-MS) analysis. Overall, our findings provide theoretical support for utilizing synergistic piezoelectric fields in PFCs to enhance system performance and pave the way for developing innovative electrodes in PFC technology.

Cost effective air-cathodes are very important for application of Microbial Fuel Cells (MFCs). Carbon fiber cloth was used as the base for preparing air-cathodes with cheap polyvinylidene fluoride (PVDF) coating on the solution-side to replace expensive Nafion as a separator regardless of the ion exchange part. The separator on the solution-side was a vital part for stable electricity generation. Another PVDF layer was coated on the air-side via a thickness-controllable method as the diffusion layer. The comparisons between Nafion and PVDF on the solution-side of cathode in electricity generation and fouling/regeneration were tested in MFCs without any catalyst. The cell voltage of the Nafion air-cathode MFC (0.23 V) was slightly higher than the PVDF MFC (0.2 V). Biofouling and cation deposition on air-cathodes became more severe with time, negatively affecting electricity generation. Soaking the air-cathode with solution-side Nafion in HCl (maximum power density: 338.1 mW m⁻²) can regenerate the cathodes and enhance the electricity generation much more than that regenerated by ultraviolet light (UV) irradiation.

This work constructed a g-C ₃ N ₄ –ZnO@PVDF film to boost piezo-photocatalysis. PVDF piezofield suppresses electron-hole recombination, while the g-C ₃ N ₄ –ZnO heterojunction guides directional electron transport, achieving 99.15% tetracycline degradation.