Figure 8 UV–vis spectra of the Rh.B concentration against CdSe, CdSe-TiO 2 , and CdSe-C 60 /TiO 2 composites. The enhanced activity is probably attributed to the improved optical absorption and the heterostructure which favors the separation of photo-introduced electron–hole pairs in

CdSe-TiO2 photocatalyst [28]. Figure 9a shows the scheme of excitation and charge transfer process between CdSe and TiO2 under visible-light irradiation. Under irradiation by UV or visible lamp, both CdSe and TiO2 can be excited; the generated electrons in CdSe and holes in TiO2 are then immigrated to the conduction band (CB) of TiO2 and the valence band (VB) of CdSe, respectively. This transfer process is thermodynamically favorable due to the bandgap (both the CB and VB) of CdSe that lie at the upper position than that of TiO2. The lifetime HIF inhibitor of the excited electrons (e −) and holes (h +) is prolonged in the transfer process, inducing higher quantum efficiency. Meanwhile, the generated electrons probably react with dissolved oxygen molecules and produce oxygen peroxide radical O2 ·−, the positively LY2606368 ic50 charged hole (h +) may react with the OH− derived from H2O to form the hydroxyl radical OH·. The Rh.B molecule then can be photocatalytically degraded by the oxygen peroxide radical O2 ·− and hydroxyl radical OH · [29, 30]. Figure 9 Schematic diagram

of the separation of generated electrons and holes on the interface of compounds. (a) CdSe-TiO2 and (b) CdSe-C60/TiO2 compounds under visible-light irradiation. CdSe-C60/TiO2 composites have the best discoloration effect, which is due to the following reasons: (1) C60 is an energy Cyclin-dependent kinase 3 sensitizer that improves the quantum efficiency and increases charge transfer, (2) C60 can enhance the adsorption effect during the discoloration

processes, and (3) CdSe can provide excited electrons for TiO2 and engender hydroxyl radicals (·OH) and superoxide radical anions (·O2 −) with the presence of H2O and oxygen. Figure 9b shows a schematic diagram of the separation of photogenerated electrons and holes on the CdSe-C60/TiO2 interface [31, 32]. Conclusions Photocatalysts were synthesized successfully using a simple sol–gel method. From the XRD patterns, the cubic crystal structure of CdSe was observed. TEM showed that the surface of TiO2 has been coated uniformly with C60 and CdSe layers with a C60 particle size of approximately 20 nm. The diffuse reflectance spectra indicated that the composites showed strong photoabsorption in the UV–vis range, and the presence of C60 enhanced the level of photoabsorption in the visible range. The nitrogen adsorption isotherms show that the added C60 can enhance the adsorption effect significantly. The photocatalytic activity of the CdSe-C60/TiO2 composite was examined by the degradation of MB in aqueous solutions under visible-light irradiation. The CdSe-C60/TiO2 composites showed good adsorption and degradation effects.