TY - JOUR
T1 - Recombination pathways in the degussa P25 formulation of TiO 2
T2 - Surface versus lattice mechanisms
AU - Hurum, Deanna C.
AU - Gray, Kimberly A
AU - Rajh, Tyana
AU - Thurnauer, Marion C.
PY - 2005/1/20
Y1 - 2005/1/20
N2 - Charge migration between electron trapping sites within the mixed-phase titania photocatalyst Degussa P25 has been studied. In addition to previously described lattice electron trapping sites on both anatase and rutile phases, surface electron trapping sites and an anatase-rutile interface trapping site specific to Degussa P25 are identified. The relationship between these sites and recombination with surface hole trapping sites is also determined. It is experimentally shown that upon band-gap illumination holes appear at the surface and preferentially recombine with electrons in surface trapping sites. These findings indicate that in mixed-phase TiO 2, such as Degussa P25, photogenerated holes are trapped exclusively on the particle surface, while photogenerated electrons are trapped within the nanoparticle lattice. Recombination reactions are dominated by surface reactions that follow charge migration. These findings indicate that, in mixed-phase TiO 2, such as Degussa P25, a random flight mechanism of recombination predominates. Such knowledge simplifies the mechanistic mathematical models used for process design and points the way for improving future oxidative titania catalysts.
AB - Charge migration between electron trapping sites within the mixed-phase titania photocatalyst Degussa P25 has been studied. In addition to previously described lattice electron trapping sites on both anatase and rutile phases, surface electron trapping sites and an anatase-rutile interface trapping site specific to Degussa P25 are identified. The relationship between these sites and recombination with surface hole trapping sites is also determined. It is experimentally shown that upon band-gap illumination holes appear at the surface and preferentially recombine with electrons in surface trapping sites. These findings indicate that in mixed-phase TiO 2, such as Degussa P25, photogenerated holes are trapped exclusively on the particle surface, while photogenerated electrons are trapped within the nanoparticle lattice. Recombination reactions are dominated by surface reactions that follow charge migration. These findings indicate that, in mixed-phase TiO 2, such as Degussa P25, a random flight mechanism of recombination predominates. Such knowledge simplifies the mechanistic mathematical models used for process design and points the way for improving future oxidative titania catalysts.
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U2 - 10.1021/jp045395d
DO - 10.1021/jp045395d
M3 - Article
C2 - 16866468
AN - SCOPUS:13244292473
SN - 1520-6106
VL - 109
SP - 977
EP - 980
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 2
ER -