Role of CdO addition on the growth and photocatalytic activity of electrospun ZnO nanofibers: UV vs. visible light

Highlights: • Electrospun (ZnO)1−x(CdO)x nanofibers as a visible active photocatalyst were prepared. • The influence of annealing rate on the band gap energy of nanofibers was reported. • Dye photo-degradation improved by increasing annealing rate. • The relation between PL peak intensity and photocatalytic activity was verified. - Abstract: (ZnO)1−x(CdO)x nanofibers were fabricated via electrospinning of polymer precursor by subsequent annealing in air. Field emission scanning electron microscopy (FESEM) showed the smooth and beadless nanofibers and X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) showed the ZnO hexagonal and the CdO cubic structure. Diffuse reflectance spectroscopy (DRS) showed the band gap energy reduction by increasing the amount of CdO in (ZnO)1−x(CdO)x nanofibers that resulted in the photocatalytic activity under the visible light for dye degradation. Under the UV light CdO acted as both electron and hole sink in the (ZnO)1−x(CdO)x nanofibers and a possible photocatalytic activity mechanism was proposed. The effect of annealing rate on the nanofiber properties was also studied. Thermal gravimetric analysis (TGA) plot revealed that different heating rates influence on both peak position and maximum amount of decomposition. Improvement of the crystallinity and the increase in the photocatalytic activity were obtained by increasing the annealing rate from 3 to 20 °C/min