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Journal of Organic & Inorganic Chemistry
ISSN 2472-1123
2
n d
E d i t i o n o f E u r o S c i C o n C o n f e r e n c e o n
Chemistry
F e b r u a r y 1 9 - 2 0 , 2 0 1 9
P r a g u e , C z e c h R e p u b l i c
Chemistry 2019
U
nderstanding of the fundamentals behind charge carrier dynamics of photocatalyticmaterials is still illusive, hindering progress
in our quest for renewable energy. TiO2 anatase and rutile are the most understood phases in photocatalysis and serve as the
best model systems for fundamental studies. The ultrafast charge carrier dynamics, especially on TiO2 anatase single crystals
(the most active phase), are unresolved. The femtosecond time-resolved spectroscopy was carried out to explore the dynamics
of photoexcited charge carriers’ recombination in the anatase single crystal, for the first time using pump fluence effects, and
we compared it to that in the rutile single crystal. A significant difference in charge carrier recombination rates between both
crystals is recorded. More specifically, we found that the time constants for carrier recombination are two orders of magnitude
slower for anatase (101) when compared to those of rutile (110). Moreover, bulk defects introduced by reduction of the samples
via annealing in ultrahigh vacuum resulted in faster recombination rates for both polymorphs. Both states (fresh and reduced)
probed by pump fluence dependence measurements revealed that the major recombination channel in fresh and reduced anatase
and reduced rutile is first-order Shockley−Read−Hall-mediated. However, for fresh rutile, third-body Auger recombination was
observed and attributed to the presence of higher density of intrinsic charge carriers. At all excitation wavelengths and fluence
investigated, the anatase (101) single crystal shows longer charge carrier lifetimes when compared to the rutile (110) single
crystal. This may explain the superiority of the anatase phase than the rutile phase in M/TiO2 catalysts for molecular hydrogen
production.
partha.maity@kaust.edu.saStudy of charge carrier dynamics in anatase and
rutile TiO2: implications on photocatalytic water
splitting
Partha Maity
1
and Hicham Idriss
2
1
King Abdullah University of Science and Technology (KAUST), Kingdom of Saudi Arabia
2
SABIC-CRD, KAUST, Kingdom of Saudi Arabia
J Org Inorg Chem 2019, Volume: 5
DOI: 10.21767/2472-1123-C1-021