In-situ hydrothermal fabrication of Bi25FeO40/BiFeO3 heterojunction with trinary synergy of piezo-photocatalysis and peroxymonosulfate activation for efficient tetracycline degradation

Photocatalytic degradation of organic pollutants is often limited by photocatalysts’ rapid charge carrier recombination and insufficient generation of reactive species, leading to low efficiency. To address these issues, we propose a piezo-photocatalytic-Fenton system based on an in-situ co-growth Bi 25 FeO 40 /BiFeO 3 heterojunction that simultaneously enhances charge separation and activates peroxymonosulfate (PMS). Guided by density functional theory (DFT) calculations, a high-crystallinity cubic-like Bi 25 FeO 40 /BiFeO 3 heterojunction was synthesized via a facile in-situ co-growth one-step hydrothermal method, and characterized by SEM, TEM, XRD, XPS, etc. Its piezo-photocatalytic-Fenton performance was evaluated for tetracycline hydrochloride (TCH) degradation using PMS as an oxidant. Under the synergistic action of visible light, ultrasonic vibration, and PMS activation, the optimized catalyst exhibits an apparent degradation rate constant 4.3 and 35 times higher than that of BiFeO 3 under pure photocatalytic and piezocatalytic conditions, respectively. Radical scavenging tests and electron paramagnetic resonance (EPR) analyses identify superoxide radicals as the primary reactive species, with additional contributions from other reactive oxygen species (ROS). Piezoelectric force microscopy shows a high effective piezoelectric coefficient (d 33 ) of 417.5 pm/V, confirming efficient mechanical-to-electrical energy conversion, while Bi 3+ /Bi 0 and Fe 2+ /Fe 3+ redox cycling under light drives PMS activation and boosts ROS generation. This work demonstrates a rationally designed piezo-photocatalytic-Fenton heterojunction that significantly improves antibiotic degradation efficiency and provides a general strategy for coupling piezoelectric effects with PMS-based advanced oxidation processes.