The UV ndash vis diffuse reflectance spectra of as prepared
The UV–vis diffuse reflectance spectra of as-prepared MoS2/TiO2 composites were investigated and shown in Fig. 7(a). The pure TiO2 sample shows Staurosporine from the UV through the visible range up to 380 nm. After introducing of MoS2, the UV–vis diffuse reflectance spectra of MoS2/TiO2 samples show characteristic absorption corresponding to that of TiO2 and enhanced absorption in the visible light region as compared to pure TiO2 sample, which can be ascribed to the absorption of MoS2. The absorption intensity in the visible light region of the MoS2/TiO2 samples strengthened with the increasing MoS2 contents, which agrees with the color of the as-prepared samples that varies from white to gray. In Fig. 7(b), ZnTCPP-MoS2/TiO2 composite shows the characteristic absorption of ZnTCPP peaks at 415, 560 and 600 nm, which is similar to that of the corresponding solution spectra. The result indicates that the ZnTCPP complex was anchored successfully on the surface of TiO2, and the ZnTCPP-MoS2/TiO2 composite has an enhanced ability to harvest visible light as compared to the MoS2/TiO2 sample. To investigate electron transfer efficiency from the excited dye molecules to TiO2 conduction band, the photocurrent response of the ZnTCPP sensitized TiO2 electrode was tested in a nitrogen-saturated 0.5 M Na2SO4 aqueous solution under visible light illumination (λ > 420 nm). As shown in Fig. 8(a), visible light illumination (λ > 420 nm) of ZnTCPP-TiO2 electrode can generate a saturation photocurrent with a value of 1.35 μA cm−2, which suggests that an efficient photoinduced electron transfer process is occurring between ZnTCPP and TiO2.