Photoelectric catalytic degradation of methylene blue by C60-modified TiO2 nanotube array

Fullerene (C60)-modified TiO2 nanotube array (TNA) was prepared by the electrophoresis deposition technique. The as-prepared samples showed the high efficiency for the photoelectric catalytic (PEC) degradation of nonbiodegradable azodyes methylene blue (MB). The highest PEC activity of C60-modified TNA (TNA/C60) was achieved at a lower bias potential (4.0 V), which was 2.3 times of the highest activity of TNA at 5.0 V. The high PEC activity came from the synergetic effect between C60 and TiO2, which promoted the charge separation, influenced the charge distribution of the electrical double layer and reduced the impedances of the Helemholtz and depletion layers. Moreover, the oxidation of MB was a quick process during the PEC degradation, and the process began with the oxidation of the dimethylamino group, which was different from the photocatalytic (PC) process began with the oxidation of S atom; MB was mineralized completely during PEC degradation.