Synthesis, electron transfer and photocatalytic activity of TiO2 nanotubes sensitized by meso-tetra(4-carboxyphenyl)porphyrin under visible-light irradiation

Abstract

TiO₂ plays a crucial role in the materials field due to its excellent chemical and physical properties. However, the TiO₂ band edge is located in the UV region, which makes this species inactive under visible light irradiation. Porphyrins have drawn a great deal of attention as sensitizers due to the large absorption coefficients of their Soret and Q bands in the visible region. Here, we applied a new strategy using TiO₂ nanotubes sensitized by meso-tetra(4-carboxyphenyl)porphyrin (H₂TCPP) to broaden the absorption spectra to fill the valley between the Soret and Q bands. With this novel approach, TEM, DRS, XRD and XPS were employed to confirm that the TiO₂ nanotubes were successfully sensitized by the H₂TCPP, EPR and PL emission spectra showed that excited electrons transfer more effectively, and the photo-generated electron–hole pairs separated more effectively under visible light irradiation. Therefore, TiO₂ nanotubes sensitized by H₂TCPP can be used to increase the photo-generated electron activity when used as a visible-light photocatalyst under visible light irradiation.