Gd-doped BiFeO3 crystalline nanofibers for efficient rhodamine B in wastewater removal under simulated sunlight

This work synthesized a series of Gd-doped BiFeO3 (BGFO) hollow nanofibers by electrostatic spinning technique. The wall thickness of the hollow nanofibers was about 100 nm with an average grain size of 20 nm. The crystal structure distortion was found, and the BiFeO3 coexisted with rhombohedral and orthorhombic phases. The degradation efficiency of Gd-doped samples for RhB under simulated sunlight irradiation was higher than that of pure BiFeO3 nanofibers. Among them, the degradation rate of 10BGFO nanofibers on RhB was the fastest and reached 96.3% within 30 min. After five cycles, the removal efficiency could still be maintained at about 90%. The effects of temperatures, ions, concentrations, and water quality on the removal efficiency were studied in detail, and the possible photocatalytic degradation mechanism of BGFO nanofibers was also elaborated. With the increase of Gd doping, the band gap value gradually decreased, and the specific surface area was bigger, which effectively promoted the charge separation and could inhibit the complexation of photogenerated electrons and holes and produced more active substances (·O2-, h+). This study can provide a novel, reusable, flexible photocatalyst to purify dye wastewater.