SYNTHESIS OF POLYPYRROLE/TIO NANOPARTICLES IN WATER BY CHEMICAL OXIDATIVE POLYMERIZATION - Biomaterial Applications: Macro to Nanoscales - page 90

ment of the photoresponse (Fig. 4.13). Upon illumination, the electrons in
PPy are excited to the conduction band. Since the LUMO level of TiO 2 is
lower in energy than that of PPy, a strong driving force is generated which
injects the excited electrons to the conduction band of TiO 2 , while the
holes are left in the PPy. The electron injection is important to generate the
photocurrents [62].
FIGURE 4.12 UV-vis absorption spectrum of PPy/TiO 2 composite from the paper [53]
(Reproduced with permission from Journal of Materials Research, 2009, 24, P. 2547-2554.
Copyright © Materials Research Society 2009).
FIGURE 4.13 Schematic diagram of the energy levels of the PPy-TiO 2 electrode [61]
representing the possible mechanism of enhancement of TiO 2 photocatalytic properties
when embedded in the PPy.