This observation suggests that the photocatalytic activity of the hybrid nanocatalyst was enhanced under irradiation with visible light. Figure 5 UV-Vis absorption spectra of MB solutions after photocatalysis for different illumination times. With TiO2/MWCNT nanocatalysts under UV (a) and VL (b) irradiation. The percentage of MB removed after 120 min under UV and VL illumination is presented in Figure 6. Under both illumination conditions, an insignificant reduction of the blank MB (without the catalyst) was observed in the solution, which confirms that MB cannot be degraded without a catalyst. Under UV illumination, the solution with the
learn more TiO2/MWCNTs nanocatalyst removed 34.9% of the MB. The surprising result was obtained while 96.3% of MB was removed when the solution was irradiated with VL. This result indicates that the TiO2/MWCNTs nanocatalyst prepared in this work is extremely photoactive under irradiation with VL, which results from that MWCNTs can act as a photosensitising agent when excited under visible-light irradiation [50, 51]. Importantly, although only 1 mg of nanocatalyst
was used in this work, the MB degradation was more extensive than that reported previously [52–54], indicating a promising future of this nanocatalyst. Figure 6 Photocatalytic degradation behaviours of MB over TiO 2 /MWCNT nanocatalysts under UV and VL irradiation. Conclusions We successfully RG7112 ic50 synthesised a hybrid nanocatalyst by attaching TiO2 nanoparticles onto MWCNTs at a weight ratio of 50% using a novel one-step method.
The microstructure and morphology of the hybrid nanocatalyst Fossariinae were characterised by XRD, FESEM and TEM. The results showed that the anatase-phase TiO2 nanoparticles were attached to the surface of the MWCNTs. The BET surface area of the MWCNTs decreased after the TiO2 was attached to their surface. In addition, the efficiency of MB degradation under visible light was substantially greater compared to the efficiency under ultraviolet irradiation. These results indicate that MWCNTs can act as a photosensitiser agent and are excited under visible-light irradiation. Acknowledgements The authors would like to thank Universiti Kebangsaan Malaysia for providing the financial support for this work through DIP-2012-32 and DPP-2013-048 research grants. References 1. Murugan K, Rao TN, Gandhi AS, Murty B: Effect of aggregation of methylene blue dye on TiO 2 surface in self-cleaning studies. Catal Commun 2010, 11:518–521.check details CrossRef 2. Schäfer A, Nghiem L, Waite T: Removal of the natural hormone estrone from aqueous solutions using nanofiltration and reverse osmosis. Environ Sci Technol 2003, 37:182–188.CrossRef 3. Zhang M, Wang J, Fu H: Preparation and photocatalytic activity of nanocrystalline TiO 2 with uniform shape and size. J Mater Process Technol 2008, 199:274–278.CrossRef 4.