A novel PVDF-TiO2@g-C3N4 composite electrospun fiber for efficient photocatalytic degradation of tetracycline under visible light irradiation.

A novel composite electrospun fiber with high photocatalytic efficiency, good stability, strong hydrophobicity, good pollution resistance, and easy separation and recovery was synthesized. The TiO2@g-C3N4 (TCN) with special core-shell structure (5-10 nm shell) facilitated the separation of photogenerated electron-holes and had high photocatalytic performance. The poly (vinylidene fluoride) (PVDF) electrospun fiber immobilized with TCN was successfully fabricated (PVDF-TCN) with uniform distribution and size of nanofibers by using electrospinning, which was used for degrading tetracycline under visible-light irradiation (> 400 nm). A special rougher surface of electrospun fiber obtained by washing of sacrificial PVP increased the specific surface area, which became more conducive to the adhesion of the catalyst. The water contact angle and FTIR results demonstrated that the electrospun fiber became extremely hydrophilic after adding TCN catalyst, which could effectively mitigate the fiber pollution. The PVDF-TCN-0.2g electrospun fiber exhibited excellent photocatalytic performance and the degradation efficiency of tetracycline was up to 97% in 300 min under visible-light irradiation. The mechanism of PVDF-TCN electrospun fiber degradation of tetracycline in the photocatalytic process was also proposed. In addition, the PVDF-TCN-0.2g exhibited a stable activity after 4 cycles experiments since the degradation efficiency remained about 90%. Therefore, we believed this study provided a new strategy in catalyst immobilization and wastewater treatment.