Improving the Visible Light Absorption and Photocatalytic Degradation Activity of TiO2 Particles Towards MB by Organic Sensitizer Decoration.

Due to the advantages of non-toxicity, high chemical stability, high activity and low cost, TiO2 is deemed as ideal material for photocatalytic degradation. However, due to its relatively high band-gap energy, anatase TiO2 can only absorb UV light and light with higher energy. In this work, the anatase TiO2 particles were decorated with two organic photosensitizers hemin and eosin Y. The morphology and chemical structure of the composites were verified by SEM, XRD patterns and Raman spectra, the light absorption ability and generation of free radicals were also investigated. The band-gap energy of TiO2, hemin/TiO2 and EY/TiO2 were found to be 2.82 eV, 0.72 eV and 0.95 eV, respectively. Additionally, absorption of more visible light and generation of more superoxide radicals were achieved after decoration of photosensitizers. Consequently, the photocatalytic degradation activity was largely improved, when the TiO2 particles was decorated with 3% of hemin, the degradation rate of methyl blue reached 76.89% and 63.82% in 120 min under UV light and visible light, respectively, which were 1.86 and 1.84 times that of neat TiO2. Comparatively, the ferric ions in hemin may capture the electrons generated by TiO2 and then deliver the electrons to oxygen to generate more superoxide radicals, thus hemin/TiO2 exhibits higher photocatalytic degradation activity than EY/TiO2. [ABSTRACT FROM AUTHOR]