Addressing the limitations of poor piezoelectric photocatalytic activity and insufficient magnetic recovery in pure BiFeO3 nanoparticles, Gd and Zr co-doped BiFeO3 nanoparticles were synthesized via the sol-gel method. The structural characterization revealed a rhombohedral-to-orthorhombic phase transition with reduced grain size (~35 nm) and lattice distortion due to dopant incorporation. An XPS analysis confirmed Fe3+ dominance and oxygen vacancy enrichment, while optimized BGFZ9 exhibited enhanced remanent magnetization (0.1753 emu/g, 14.14 increase) compared to undoped BFO. The synergistic piezo-photocatalytic system achieved 81.08% Ofloxacin degradation within 120 min (rate constant: 0.0136 min−1, 1.26 higher than BFO) through stress-induced piezoelectric fields that promoted electron transfer for ·O2−/·OH radical generation via O2 reduction. The Ofloxacin degradation efficiency decreased to 24.36% after four cycles, with structural integrity confirmed by XRD phase stability. This work demonstrates a triple-optimization mechanism (crystal phase engineering, defect modulation, and magnetic enhancement) for designing magnetically recoverable multiferroic catalysts in pharmaceutical wastewater treatment.

To address rapid carrier recombination and low magnetic separation efficiency in piezocatalysis, Gd/Ni co-doped BiFeO₃ nanoparticles were synthesized via a sol–gel method.

The persistence of fluoroquinolone antibiotics like OFL in aquatic environments poses a significant ecological and public health risk due to their poor biodegradability and potential to induce antibiotic resistance. This study reports the fabrication of free-standing, flexible nanofibrous films via electrospinning, incorporating optimal BGFZ9 nanoparticles into a P(VDF-HFP) matrix (denoted as P(VDF-HFP)@BGFZ9). Comprehensive characterization reveals that the BGFZ9 nanoparticles act as effective heterogeneous nucleating agents, significantly promoting the formation of piezoelectric β-phase in P(VDF-HFP) and enhancing the ferroelectric polarization of the composite through interfacial coupling. Under ultrasonic excitation, the composite film exhibits remarkable piezocatalytic performance for OFL degradation, following pseudo-first-order kinetics. The film with an optimal 10% BGFZ9 loading achieves a reaction rate constant of 0.684 min^–1·g^–1 under piezocatalysis, which is approximately 1.22 times higher than that of the pure polymer film. A synergistic piezophotocatalytic effect is observed under combined ultrasonic and light irradiation, leading to an OFL removal efficiency of 85.71% within 3 h and a further increased rate constant of 1.043 min^–1·g^–1. Radical scavenger experiments and EPR spectroscopy identify superoxide radicals •O₂^– and h⁺ as the primary reactive species responsible for the degradation. The composite film demonstrates excellent cycling stability, retaining 94.4% of its initial activity after five consecutive runs, alongside robust structural integrity. This work provides a novel strategy for developing efficient, stable, and easily recyclable flexible piezocatalytic materials for antibiotic wastewater remediation.

This study presents a novel strategy to significantly enhance the piezocatalytic performance of BiFeO₃ for antibiotic degradation by integrating cation co-doping and noble metal decoration. To address the inherent limitations of rapid charge recombination and insufficient active sites in pristine BiFeO₃, Gd, and Zr co-doped BiFeO₃ (BGFZ9) NPs were first synthesized via a sol-gel method. Subsequently, Ag NPs were uniformly deposited on the BGFZ9 surface through a facile photochemical reduction process to construct Ag/BGFZ9 nanocomposites. Comprehensive characterizations including XRD, XPS, TEM, and VSM confirmed the successful formation of the perovskite structure, uniform dispersion of Ag NPs, and tailored magnetic properties. The optimized Ag2/BGFZ9 catalyst demonstrated remarkable piezocatalytic and piezo-photocatalytic activity towards ofloxacin, achieving degradation efficiencies of 82.54 and 86.98% within 120 min under ultrasonic and combined ultrasonic/visible-light irradiation, respectively. The corresponding first-order rate constants were 0.0147 and 0.0164 min^–1, representing a significant enhancement over the undoped and unmodified counterparts. The superior performance is attributed to the synergistic interplay of multiple factors: (1) the Gd/Zr co-doping induced lattice distortion and optimized band structure, enhancing the intrinsic piezoelectric response; (2) the formation of a Schottky junction at the Ag/BGFZ9 interface, which acted as an efficient electron sink to suppress charge carrier recombination; and (3) the LSPR effect of Ag NPs under visible light, which broadened light absorption and generated hot electrons. Radical trapping experiments and EPR spectroscopy identified \( \bullet {\kern 1pt} {\text{O}}_{2}^{ - }\) and \( \bullet {\kern 1pt} {\text{OH}}\) as the primary reactive oxygen species. The catalyst maintained 82.13% of its initial activity after five consecutive cycles, demonstrating excellent stability and magnetic recoverability. This work elucidates a synergistic piezoelectric-plasmonic coupling mechanism and provides a viable design principle for developing efficient, stable, and magnetically separable multiferroic catalysts for advanced oxidation processes in wastewater remediation.