The results show that MB was only slightly degraded in the dark when TiO2 was used as a
catalyst. Better catalytic activity was obtained when the hybrid metal oxide (TiO2/TiO2–V2O5) was
Fig. 5.. Furthermore, by using (TiO2/TiO2–V2O5/PPy) nanocomposites as the catalyst, the catalytic activity
in the dark was slightly improved. The above effects can be ascribed to the light of the energy storage
ability of the hybrid metal oxide (TiO2/TiO2–V2O5) (see also Fig. 9). Upon UV irradiation,
photoexcited electrons were generated, some of which were kept in the electron storage substance
(TiO2–V2O5). In the dark, however, these electrons were released to carry on the degradation of methylene
blue. In other words, TiO2–V2O5 was charged under UV light, and was discharged in the dark to
activate TiO2.