Abstract
Tungsten-doped titanium dioxide (TiO2:W) has been reported to have increased photocatalytic performance as compared to undoped TiO2. The exact mechanism behind this has been debated. Consequently, the purpose of this work is twofold: (i) synthesize TiO2:W films with improved optoelectronic properties and (ii) refine the understanding of photocharge properties in tungsten-doped TiO2. An in situ radio frequency magnetron-sputtering deposition process was used to fabricate undoped (TiO2), oxygen deficient (TiO2-x), and tungsten-doped (TiO2:W) films with varying dopant levels. X-ray photoelectron spectroscopy measurements showed the presence of both WTi″ and WTix type dopants that led to significantly reduced oxygen vacancy (VO) densities. These observations were corroborated by X-ray diffraction analysis, which revealed that the improved stoichiometry resulted in a marked enhancement of the rutile phase as compared to the sub-stoichiometric (VO-doped) samples. Critically, high-frequency dielectric spectroscopy measurements revealed an optimal tungsten doping level of ∼2.5 at. %. This point showed the greatest tungsten induced reduction in the 2[TiIII]-[VO″] defect pair ϵ′ contribution, i.e., almost two orders of magnitude. Finally, this dielectrically observed reduction in VO was correlated to an increase in photocharge decay lifetimes. In other words, photocharge lifetimes increased in accordance with the reduction of VO defects brought on by tungsten doping.
| Original language | English |
|---|---|
| Article number | 205103 |
| Journal | Journal of Applied Physics |
| Volume | 125 |
| Issue number | 20 |
| DOIs | |
| Publication status | Published - May 28 2019 |
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ASJC Scopus subject areas
- Physics and Astronomy(all)
Cite this
High-frequency dielectric characterization of electronic defect states in co-sputtered W-doped TiO2. / Delegan, N.; Teranisi, Takasi; El Khakani, M. A.
In: Journal of Applied Physics, Vol. 125, No. 20, 205103, 28.05.2019.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - High-frequency dielectric characterization of electronic defect states in co-sputtered W-doped TiO2
AU - Delegan, N.
AU - Teranisi, Takasi
AU - El Khakani, M. A.
PY - 2019/5/28
Y1 - 2019/5/28
N2 - Tungsten-doped titanium dioxide (TiO2:W) has been reported to have increased photocatalytic performance as compared to undoped TiO2. The exact mechanism behind this has been debated. Consequently, the purpose of this work is twofold: (i) synthesize TiO2:W films with improved optoelectronic properties and (ii) refine the understanding of photocharge properties in tungsten-doped TiO2. An in situ radio frequency magnetron-sputtering deposition process was used to fabricate undoped (TiO2), oxygen deficient (TiO2-x), and tungsten-doped (TiO2:W) films with varying dopant levels. X-ray photoelectron spectroscopy measurements showed the presence of both WTi″ and WTix type dopants that led to significantly reduced oxygen vacancy (VO) densities. These observations were corroborated by X-ray diffraction analysis, which revealed that the improved stoichiometry resulted in a marked enhancement of the rutile phase as compared to the sub-stoichiometric (VO-doped) samples. Critically, high-frequency dielectric spectroscopy measurements revealed an optimal tungsten doping level of ∼2.5 at. %. This point showed the greatest tungsten induced reduction in the 2[TiIII]-[VO″] defect pair ϵ′ contribution, i.e., almost two orders of magnitude. Finally, this dielectrically observed reduction in VO was correlated to an increase in photocharge decay lifetimes. In other words, photocharge lifetimes increased in accordance with the reduction of VO defects brought on by tungsten doping.
AB - Tungsten-doped titanium dioxide (TiO2:W) has been reported to have increased photocatalytic performance as compared to undoped TiO2. The exact mechanism behind this has been debated. Consequently, the purpose of this work is twofold: (i) synthesize TiO2:W films with improved optoelectronic properties and (ii) refine the understanding of photocharge properties in tungsten-doped TiO2. An in situ radio frequency magnetron-sputtering deposition process was used to fabricate undoped (TiO2), oxygen deficient (TiO2-x), and tungsten-doped (TiO2:W) films with varying dopant levels. X-ray photoelectron spectroscopy measurements showed the presence of both WTi″ and WTix type dopants that led to significantly reduced oxygen vacancy (VO) densities. These observations were corroborated by X-ray diffraction analysis, which revealed that the improved stoichiometry resulted in a marked enhancement of the rutile phase as compared to the sub-stoichiometric (VO-doped) samples. Critically, high-frequency dielectric spectroscopy measurements revealed an optimal tungsten doping level of ∼2.5 at. %. This point showed the greatest tungsten induced reduction in the 2[TiIII]-[VO″] defect pair ϵ′ contribution, i.e., almost two orders of magnitude. Finally, this dielectrically observed reduction in VO was correlated to an increase in photocharge decay lifetimes. In other words, photocharge lifetimes increased in accordance with the reduction of VO defects brought on by tungsten doping.
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UR - http://www.scopus.com/inward/citedby.url?scp=85066120310&partnerID=8YFLogxK
U2 - 10.1063/1.5087061
DO - 10.1063/1.5087061
M3 - Article
AN - SCOPUS:85066120310
VL - 125
JO - Journal of Applied Physics
JF - Journal of Applied Physics
SN - 0021-8979
IS - 20
M1 - 205103
ER -