Comparative Photocatalytic Ability of Nanocrystal-Carbon Nanotube and -TiO2 Nanocrystal Hybrid Nanostructures

We synthesized various nanocrystal (e.g., CdS, CdSe, and Cu 2 S)-carbon nanotube (NC-CNT) and NC-TiO 2 hybrid nanostructures using the solvothermal method and compared their photocatalytic ability toward the visible-light-driven degradation of methylene blue (MB) dye. The free CdS NCs exhibited higher degradation efficiency than the CdSe and Cu 2 S NCs. The photocatalytic abilities of the NCs were found to determine the relative degradation efficiency of their CNT and TiO 2 hybrid nanostructures. These results suggest that the oxidative N-demethylation degradation involves the transfer of holes from the NCs to MB. The hybridization of the NCs with the TiO 2 NCs and CNTs enhances the oxidative degradation rate to the same extent, suggesting that the interfacial electron transfer process from the NCs to the attached CNTs (or TiO 2 ), which retards the recombination of the electrons and holes, is comparable for both hybrid nanostructures.