Polyaniline/CaCu3Ti4O12 nanofiber composite with a synergistic effect on visible light photocatalysis

CaCu3Ti4O12 (CCTO)-polyaniline (PANI) nanofiber composites with different ratios of PANI/CCTO were successfully prepared by in situ polymerization and were shown to be active photocatalysts under irradiation with visible light. The as-synthesized samples were characterized by XRD, SEM, TEM, FTIR, UV-visible spectrophotometry and TGA/DSC. Significant adsorption was observed for anionic dyes because the negatively charged groups or the electron-rich groups of these dyes interacted chemically with the positively charged backbone of PANI. Photocatalytic experiments showed that PANI/CCTO nanofibers with a weight ratio of 7 : 3 showed the highest photocatalytic activity for the degradation of Congo red and methyl orange under visible light irradiation. The synergistic effect in the PANI/CCTO nanofiber composites results in a reduction of the photoinduced electron-hole recombination rate, giving a high photocatalytic activity for the degradation of the dyes under visible light irradiation. The intense photocatalytic activity can be attributed to the photogenerated electrons in PANI, which can directly transfer to the LUMO of CCTO, and the photogenerated holes in the HOMO of CCTO, which can migrate to the valance band of PANI, efficiently inhibiting direct recombination of the charge carriers.