Nanocrystalline TiO<sub>2</sub>‑Catalyzed Photoreversible Color Switching
- Publication date
- Publisher
Abstract
We
report a novel photoreversible color switching system based
on the photocatalytic activity of TiO<sub>2</sub> nanocrystals and
the redox-driven color switching property of methylene blue (MB).
This system rapidly changes from blue to colorless under UV irradiation
and recovers its original blue color under visible light irradiation.
We have identified four major competing reactions that contribute
to the photoreversible switching, among which two are dominant: the
decoloration process is mainly driven by the reduction of MB to leuco
MB by photogenerated electrons from TiO<sub>2</sub> nanocrystals under
UV irradiation, and the recoloration process operates by the TiO<sub>2</sub>-induced self-catalyzed oxidation of LMB under visible irradiation.
Compared with the conventional color switching systems based on photoisomerization
of chromophores, our system has not only low toxicity but also significantly
improved switching rate and cycling performance. It is envisioned
that this photoreversible system may promise unique opportunities
for many light-driven actuating or color switching applications