Fluid-induced piezoelectric field enhanced photocatalytic antibiotic removal over nitrogen-doped carbon quantum dots/Bi2WO6@polyvinylidene fluoride-co-hexafluoropropylene membrane in aqueous environments

Enhancing the charge separation efficiency of photocatalysts is crucial to their catalytic activity, which is still challenging. Herein, nitrogen-doped carbon quantum dots ( N -CQDs) were combined with Bi 2 WO 6 to construct an N -CQDs/Bi 2 WO 6 heterocomposite, which was loaded onto the surface of polyvinylidene fluoride- co -hexafluoropropylene (PVDF-HFP) membrane to design a flexible, porous and hydrophilic N -CQDs/Bi 2 WO 6 @PVDF-HFP photocatalytic membrane. Piezo-response force microscopy (PFM) and the maximum effective piezoelectric coefficient ( d33 ) measurements demonstrate that the PVDF-HFP membrane has favorable piezoelectric properties. Besides, fluid-induced mechanical energy can generate a piezoelectric field within the PVDF-HFP membrane. Theoretical calculations indicate that the difference in work function at the N -CQDs/Bi 2 WO 6 heterocomposite interface creates an inherent electric field. Therefore, the synergistic effect of the two electric fields improves the separation and migration efficiency of photogenerated carriers in N -CQDs/Bi 2 WO 6 heterocomposite. The membrane effectively removed 85.3 % of oxytetracycline (OTC) under the synergistic driving of water flow (900 r/min) and visible light, surpassing the results of only water flow (34.4 %) and visible light (63.1 %). Furthermore, the degradation performance of the membrane towards OTC remains almost unchanged after multiple recycles, highlighting its favorable reusability. This work addresses the issue of powdery catalysts in recovering for practical applications and underlines the potential of integrating with natural low-frequency water flows to purify organic-contaminated wastewater.