The construction of a photocatalytic fuel cell based on piezoelectric-enhanced dual heterojunctions of PVDF–HFP supported 2D/3D composites toward photocatalytic degradation of tetracycline

Abstract

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.