Title:
|
Photo-induced changes in metal oxides and their applications as self-cleaning piezoelectric based caesium sensors
|
There is current debate in literature as to the main source of photoinduced
super-hydrophilic (PSH) nature on Ti02 films with groups segregated
into two schools of thought: (i) those attributing the effect to UV induced
modifications of the Ti02 surface; and (ii) those attributing the effect to the
well-known photo-oxidation properties of Ti02 in removing hydrophobic
organic layers from the Ti02 surface. This thesis presents acquisition of
experimental goniometric data required to allow theoretical analysis of the
super-hydrophilic nature on as prepared mesoporous-Ti02 (m-Ti02), in order
to determine the source of PSH. Evidence to advocate that surface
reconstruction does not occur instantaneously upon ultra-band gap
illumination, the Ti02 surface is inherently wet with a contact angle, 8, being
4°, and the photo-induced super-hydrophilic nature is due to the latter
effect, (ii), is also discussed. Experiments demonstrating the change in the
Ti02 surface during UV band-gap illumination in the presence of organics
using micro-gravimetric techniques, mainly the quartz crystal microbalance
(QCM), are presented and exploration and applications of PSH-related
phenomena in real world sensing devices are explored.
|