A self-standing dual-electric field synergistic Janus nanofibre piezoelectric photocatalyst with degradation of antibiotics: Performances, DFT calculation and mechanism unveiling

A self-standing dual-electric field synergistic [TiO2/polyvinylidene fluoride (PVDF)]//[g-C3N4 tube/PVDF] Janus nanofibres (named as [TP]//[CTP]JNs) S-scheme heterostructure piezoelectric photocatalyst is designed and constructed via conjugative electrospinning. Dual-fields of built-in electric fields supplied by S-scheme heterostructure and piezoelectric field formed by PVDF jointly boost separation and transfer of photo-induced charges. As a case study, piezoelectric photocatalytic efficiency of [TP]//[CTP]JNs for tetracycline hydrochloride (TCH) under ultrasonic united with simulated sunlight illumination is 93.35% (40 min), which is 1.39 times of the photocatalytic efficiency (light illumination only) and 5.32 times of piezoelectric catalytic efficiency (applying ultrasonic only), proving the advantages of the synergistic effect of piezoelectric catalysis and photocatalysis on contaminant degradation. The dynamic behaviors of photocatalysis and photo-generated charges are deeply revealed through fs-TA and TRPL decay spectra, and the degradation pathways of antibiotics are reasonably speculated by combining LCMS spectra with Fukui index. By the degradation ability, COMSOL simulation and DFT calculation, the structural advantage of Janus nanofibers is fully verified, and S-scheme charge transfer mechanism is confirmed by combining a series of sound ample experiments with theoretical calculations. Additionally, the construction mechanism of Janus nanofibers is proposed, and corresponding construction technique is established.