Bi-piezoelectric and plasmonic enhanced photocatalysis using Au/Bi2WO6/PVDF flexible films for efficient dye wastewater treatment: Heterogeneous interfacial engineering, degradation pathways and mechanism insight

[Display omitted] •Alternating compression and release behaviors of integrated bi-piezoelectric fields.•Generation and operation mechanisms of hot carriers induced by LSPR effect.•Electron transfer mechanism at the Au/BWO contact interface.•Carrier transport pathways in bi-piezoelectric and plasmonic co-modulation systems.•Analysis of RhB degradation pathways and ecotoxicity evaluation of its intermediates. Photocatalytic oxidation technology has great potential in solving energy and environmental challenges. Here, an innovative theoretical framework based on Au/Bi2WO6/PVDF ternary composite films that integrates piezoelectric polarization with localized surface plasmon resonance (LSPR) was proposed, aiming to effectively break through these technical bottlenecks. Photoluminescence (PL) spectra, photocurrent density-time curves, and UV–vis diffuse reflectance spectra (UV–vis DRS) unequivocally visualize the substantial enhancement imparted by Au NPs. Under the co-excitation of illumination and ultrasonic treatment, the Au/BWO/PVDF ternary heterostructure demonstrated an impressive 98.1 % degradation rate of Rhodamine B (RhB) within 60 min and a high pseudo-first-order kinetic constant (k) of 0.0644 min−1. The superior piezo-photocatalytic degradation activity was primarily attributed to the built-in bi-piezoelectric field of BWO and PVDF as well as the LSPR effect of Au NPs. Based on liquid chromatography-mass spectrometry (LC-MS) techniques, condensed Fukui function, and frontier molecular orbital theory, we comprehensively summarized the potential degradation pathways of RhB. On this basis, the toxicological assessment results confirmed that the piezo-photocatalytic system can effectively reduce the ecological toxicity of RhB. In addition, density functional theory (DFT) calculations elucidated the charge transfer pathway at the Au/BWO contact interface, revealing the transfer of free electrons from Au to BWO.