Enhanced photocatalytic degradation and adsorption of methylene blue via TiO2 nanocrystals supported on graphene-like bamboo charcoal

摘要

In this study, a novel efficient photocatalytic nanomaterial, TiO2 nanocrystals supported on graphene-like bamboo charcoal, has been successfully synthesized via a facile multi-step process. The structural and optical properties of the as-prepared samples were characterized by different techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis absorption spectroscopy, photoluminescence spectra (PL), Raman spectra and nitrogen adsorption-desorption isotherms. The photocatalytic activities under sunlight were evaluated by the degradation of methylene blue (MB). The results indicated that the ternary hybrid photocatalysts exhibited much higher photocatalytic activities toward the degradation of MB than the pure TiO2 under UV light irradiation. Moreover, the optimum weight content of graphene-like bamboo charcoal in composite photocatalysts was 6 wt% for achieving the maximum photocatalytic degradation rate. The apparent rate constant of the best sample (0.0509 mm(-1)) was about 3 times greater than that of the commercial P25 (0.0170 mm(-1)). The adsorption and degradation kinetics of MB can be described by the pseudo-first-order model and apparent first-order kinetics model, respectively. The highly enhanced photocatalytic performance was attributed to the synergetic effect of graphene-like carbon and bamboo charcoal, which lead to the promoted charge separation and reduction reaction of oxygen, and enhanced adsorption capacities of MB, respectively. The composite photocatalysts displayed a high photochemical stability under repeated irradiation. This work may provide new insights and understanding on the graphene-like bamboo charcoal as an excellent support for photocatalyst nanoparticles to enhance their visible-light photocatalytic activity. (C) 2015 Elsevier B.V. All rights reserved.