TY - JOUR
T1 - Enhancement of the photocatalytic activity of TiO2 through spatial structuring and particle size control: From subnanometric to submillimetric length scale
AU - Aprile, Carmela
AU - Corma, Avelino
AU - Garcia, Hermenegildo
PY - 2008
Y1 - 2008
N2 - This review summarizes the physical approaches towards enhancement of the photocatalytic activity of titanium dioxide by controlling this semiconductor in a certain length scale from subnanometric to submillimetric distances and provides examples in which the photocatalytic activity of TiO2 is not promoted by doping or changes in the chemical composition, but rather by application of physical concepts and spatial structuring of the semiconductor. Thus, encapsulation inside the micropores and cavities of zeolites (about 1 nm) renders small titanium oxide clusters with harnessed photocatalytic activity. On the other hand, nanometric titanium particles can be ordered forming structured periodic mesoporous materials with high specific surface area and well defined porosity. Titiania nanotubes of micrometric length, either independent or forming a membrane, also exhibit unique photocatalytic activity as consequence of the long diffusion length of charge carriers along the nanotube axis. Finally, photonic crystals with an inverse opal structure and the even more powerful concept of photonic sponges can serve to slow down visible light photons inside the material, increasing the effective optical path in such a way that light absorption near the absorption onset of the material is enhanced considerably. All these physical-based approaches have shown their potential in enhancing the photocatalytic activity of titania, paving the way for a new generation of novel structured photocatalysts in which physical and chemical concepts are combined.
AB - This review summarizes the physical approaches towards enhancement of the photocatalytic activity of titanium dioxide by controlling this semiconductor in a certain length scale from subnanometric to submillimetric distances and provides examples in which the photocatalytic activity of TiO2 is not promoted by doping or changes in the chemical composition, but rather by application of physical concepts and spatial structuring of the semiconductor. Thus, encapsulation inside the micropores and cavities of zeolites (about 1 nm) renders small titanium oxide clusters with harnessed photocatalytic activity. On the other hand, nanometric titanium particles can be ordered forming structured periodic mesoporous materials with high specific surface area and well defined porosity. Titiania nanotubes of micrometric length, either independent or forming a membrane, also exhibit unique photocatalytic activity as consequence of the long diffusion length of charge carriers along the nanotube axis. Finally, photonic crystals with an inverse opal structure and the even more powerful concept of photonic sponges can serve to slow down visible light photons inside the material, increasing the effective optical path in such a way that light absorption near the absorption onset of the material is enhanced considerably. All these physical-based approaches have shown their potential in enhancing the photocatalytic activity of titania, paving the way for a new generation of novel structured photocatalysts in which physical and chemical concepts are combined.
UR - http://www.scopus.com/inward/record.url?scp=38849145668&partnerID=8YFLogxK
U2 - 10.1039/b712168g
DO - 10.1039/b712168g
M3 - Article
C2 - 18231679
AN - SCOPUS:38849145668
SN - 1463-9076
VL - 10
SP - 769
EP - 783
JO - PCCP : Physical Chemistry Chemical Physics
JF - PCCP : Physical Chemistry Chemical Physics
IS - 6
ER -