MoS₂/polyaniline (PANI)/polyacrylonitrile (PAN)@BiFeO₃ bilayer hollow nanofiber membrane: Photocatalytic filtration and piezoelectric effect enhancing degradation and disinfection

A novel MoS₂/polyaniline (PANI)/polyacrylonitrile (PAN)@BiFeO₃ bilayer hollow nanofiber membrane (PPBM-H) was successfully synthesized by coaxial electrospinning technique. In the nanofiber, BiFeO₃ nanoparticles (NPs) and MoS₂ nanosheets (NSs) were loaded in the middle and outer layers of the PANI/PAN composites, respectively, which constructs a type II heterojunction with spatially separated microtopography, thus significantly improving the charge separation in photocatalysis. Moreover, the hollow structure and the vast number of exposed groups on the surface of PPBM-H help to improve the mass transfer efficiency and pollutant adsorption performance in wastewater treatment. In addition, PPBM-H can generate H₂O₂ by in-situ activation of BiFeO₃/MoS₂ for photo-Fenton catalysis, enabling Fe³⁺ and Fe²⁺ recycling. Also, PPBM-H can produce piezoelectric polarisation under ultrasonic excitation, which can further enhance the efficiency of electron/hole separation and transfer, and induce the generation of active free radicals. Owing to its wonderful self-cleaning effect, the PPBM-H has good mechanical strength (2.95 Mpa), hydrophilicity (11.6°), water flux (1248 L·m⁻²·h⁻¹), BSA rejection (98.8 %), and exhibits distinguished photocatalytic filtration efficiencies (99.5 % tetracycline hydrochloride (TCH) and 99.9 % methyl orange (MO) within 60 min), piezo-photocatalysis (99.2 % TCH within 2 h), disinfection performance for Escherichia coli (E. coli) (100 %, within 60 min).