http://www.bentham.org/eng/samples/eng2-3/0002ENG.pdf
First
non-metal doped TiO2 was described in 1986 by
Sato, et al. [37]. They obtained N-TiO2 powders from a
commercial titanium hydroxide by calcination. The powders
showed higher photocatalytic activity for oxidation of carbon
monoxide and ethane than standard TiO2 in the visible region
(434 nm). But at that time, this result did not attract
attention. Only in 2001, Asashi, et al. reported the band-gap
narrowing of titanium dioxide by nitrogen doping [18]. They
prepared TiO2-xNx films by sputtering the TiO2 target in a
N2(40%)/Ar gas mixture and by treating anatase powder
(ST01, Ishihara Sangyo Kaisha, Japan) in the NH3(67%)/Ar
atmosphere at 600°C for 3 h.
Soon after, successfully prepared and exhibiting higher
photoactivity under visible light - N-doped TiO2 was
followed by other nonmetal doped titania photocatalysts such
as carbon [38] sulfur [39,40], boron [32, 41], phosphorus
[33, 42],
flour [
43] and iodine [44]. Titanium dioxide
modified with non-metal atoms was prepared by hydrolysis
of titanium precursors in the presence of dopant, followed by
calcination [29-30, 45], gas-phase thin film deposition
method [46], oxidative annealing of TiN, TiS2 or TiC powders
[27, 28, 47] and atmospheric pressure plasma-enhanced
nanoparticles synthesis
[43] Yu JC, Yu J, Ho W, Jiang Z, Zhang L. Effects of F- doping on the
photocatalytic activity and microstructures of nanocrystalline TiO2
powders. Chem Mater 2002; 14: 3808-3816.
Ag
Silver nitrate was mixed with reduction agent (sodium citrate tribasic dihydrate) and the
reaction temperature was raised to 80°C with continuous stirring. Then TIP and HNO3
were added and the reaction was maintained at 50°C for 24 h. The prepared sol was
dried at 105°C for 24 h and calcined at 300°C.
Degradation of
nitrophenol in aqueous
phase
[22]
Fe
The reactive magnetron sputtering method: 99.99% titanium target and 99.9% iron
pieces were placed in the reaction chamber and mixture of argon and oxygen was
introduced into the chamber during discharging.
Wastewater decoloring [23]
V
Sol-gel method: Solution 1 (vanadyl acetylacetonate dissolved in n-butanol) was mixed
with solution 2 (acetic acid in titanium butoxide) and hydrolyzed (24 h) by the water
generated via the estrification of acetic and butanol. The suspension as dried at 150°C,
pulverized and calcined at 400°C for 0, 5 h.
Wastewater decoloring [24]
AuTitanium (IV) butoxide dissolved in absolute ethanol was added to solution containing
tetrachloroauric acid (HAuCl4·4H2O), acetic acid and ethanol. The resulting suspension
was aged (2 days), dried under vacuum, grinding and calcinated at 650°C.
Wastewater decoloring [25]
Metal dopants
Pt
Photoreduction process: TiO2 was suspended in a mixture of hexachloroplatinic acid in
methanol. The suspension was irradiated with a 125 W mercury lamp (60 min.). Pt-TiO2
was separated by filtration, washed with distilled water and dried at 100°C for 24 h.
Wastewater decoloring [26]
Titanium nitride (TiN) oxidation : Heating of TiN at 450-550°C for 2h in air (heating
and cooling temperature rate: 2°C/min).
Photooxidation of
aromatic compounds
(e.g. toluene)
[27]
N
Treating anatase TiO2 powder ST01 in the NH3 (67%)/Ar atmosphere at 600°C for 3 h.
Photooxidation of
acetaldehyde in gas
phase
[18]
S
Oxidation annealing of titanium disulfide (TiS2) at 300-600°C. Wastewater decoloring [28]
N, SHydrolysis of Ti(SO4)2 in NH3 aqueous solution. Precipitate was centrifuged, washed
with distilled water and alcohol. Obtained gels were dried under vacuum at 80 for 10 h
and were ground to obtain xerogel. The xerogel was calcinated at 400-800°C in air for
3 h
Photooxidation of
volatile compounds in
gas phase (e.g. acetone
and formaldehyde
[29]
Sol-gel method: TBOT was hydrolyzed in the presence of ethanol, water and nitric acid;
precipitated titanium hydroxide was dried at 110°C and calcinated in air at 150-200°C.
Degradation of NOx;
Wastewater decoloring
[30]
C
Acid-catalyzed sol-gel process. Alkoxidide precursor was dissolved in corresponding
alcohol, mixed with hydrochloric acid aqueous solution. Obtained gel was aged for
several days and calcinated in air (3 h at 65°C and 3 h at 250°C) and grounded.
Photooxidation of
phenol compounds in
aqueous phase
[31]
B[/B
]Anatase TiO2 powder (ST01) was grinding with boric acid triethyl ester and calcinated
in air at 450°C.
Photooxidation of
phenol compounds in
aqueous phase
[32]
Nonmetal dopants
PSol-gel method: TIP was hydrolyzed in the presence of isopropanol and water, After
hydrolysis phosphoric acid was added. Dispersion was stirred for 2h, centrifuged at
3500 rpm and dried at 100°C. Obtained powder was calcinated at 300°C.
Photooxidation of
phenol compounds in
aqueous phase
[33]
