Nowadays, the transportation, the industry activities, craft villages,
etc. has emitted many high-toxic compounds and harmful bacteria
harmful to human health into the air. Therefore, the polluted air is an
urgent issue that needs to be studied and solved.
A variety of methods has been employed to treat the polluting
substances in the air such as membrane filtration, adsorption by
activated carbon, thermophilization, ionization, ozone, photocatalyst,
irradiation ultraviolet etc. In particular, the titanium dioxide (TiO2)
photocatalyst possesses many outstanding advantages such as
complete conversion of toxic compounds into carbon dioxide, water,
and salts but no by-products, the ambient operation conditions, easyto-look and low cost.
However, TiO2 has some disadvantages as follows: the large
band gap (Eg 3,2eV), the reaction occurring only when the radiation
is in the ultraviolet area, the high rate of the combination of high
electron-hole pair leads to the low efficiency of photochemical
quantification and photocatalysis. Thus, doping of metals or
nonmetals is often utilized on the crystal structure of TiO2 to obtain a
catalyst that is operable in the visible light region. In all of the used
elements, nitrogen is the most frequently employed because the
process is very simple but effective
