Self-cleaning tiles and glasses for eco-efficient buildings - Nanotechnology in Eco-efficient Construction - page 330

the transformation. The transition follows fi rst order kinetics, with an activa-
tion energy of 418 kJ mol −1 . The breaking of these bonds can be affected

by a number of factors, including the addition of dopants, synthesis method
and thermal treatment. 52
Table 14.2 presents the results of a patent search using the relevant terms,
for photocatalytic tiles and glass. There are many patents which relate to
high temperature stable anatase titania such as WO2009061707 (A1), but
they do not indicate visible light active photocatalytic properties or their
intended use in building materials, for example. Most disclosures relate to
a process for making titanium dioxide in an anatase crystalline form which
is stable at temperatures above 1000°C. Another invention (CN 101205083
(A)) relates to a technology for preparing a nanometre-scale material, in
particular to a preparation method in which, after a high temperature
(above 700°C) process, nanometre crystal titanium oxide with small crystal
size and high surface area, the main anatase phase can still be retained,
something that has proved hard to obtain. The invention can realize large-
scale preparation at high temperatures (700-1,500°C) and produces the
nanometre crystal titanium oxide which is characterized by the main anatase
phase, the small crystal size, the high surface area, high crystallinity, low
surface state distribution, etc. The nanometre titanium oxide grains pre-
pared by the invention are expected to be applied in photocatalysis fi elds
such as a sensitized solar energy battery, and hydrogen prepared by water
splitting.

∼

Table 14.2 Patent search for photocatalytic tiles and glass

No. of
patents

Patents
relevant Search terms Brief description

High temp, stable,
anatase

1 1 Precipitating a halide salt and a

hydrolysed compound comprising
Ti from a reaction mixture

￿ ￿ ￿ ￿ ￿ ￿

Photocatalytic,
titanium dioxide

85 2 See text

Ceramic building
material,
photocatalytic

1 1 To form a strong photocatalytic

layer taking advantage of
remaining heat immediately after
burning by directly spraying a
photocatalyst liquid on a ceramic
substrate in a cooling stage
immediately after burning

Photocatalytic, TiO 2
antibacterial

3 1 See text

High temperature
anatase, ceramic,
antibacterial

3 1 See text