Electronic Structure, Optical Properties, and Photoelectrochemical Activity of Sn-Doped Fe2O3 Thin Films

Tian, C. M.1; Li, W-W2; Lin, Y. M.1; Yang, Z. Z.3; Wang, L.3; Du, Y. G.3; Xiao, H. Y.4; Qiao, L.4; Zhang, J. Y.1,5; Chen, L.5; Qi, Dong-Chen6; MacManus-Driscoll, J. L.2; Zhang, K. H. L.1,2

2020-06-11

10.1021/acs.jpcc.0c02875

Journal of Physical Chemistry C   影响因子和分区

1932-7447

1932-7455

Hematite (Fe2O3) is a well-known oxide semiconductor suitable for photoelectrochemical (PEC) water splitting and industry gas sensing. It is widely known that Sn doping of Fe2O3 can enhance the device performance, yet the underlying mechanism remains elusive. In this work, we determine the relationship between electronic structure, optical properties, and PEC activity of Sn-doped Fe2O3 by studying highly crystalline, well-controlled thin films prepared by pulsed laser deposition (PLD). We show that Sn doping substantially increases the n-type conductivity of Fe2O3, and the conduction mechanism is better described by a small-polaron hopping (SPH) model. Only 0.2% Sn doping significantly reduces the activation energy barrier for SPH conduction from at least 0.5 eV for undoped Fe2O3 to 0.14 eV for doped ones. A combination of X-ray photoemission, X-ray absorption spectroscopy, and DFT calculations reveals that the Fermi level gradually shifts toward the conduction band minimum with Sn doping. A localized Fe2+-like gap state is observed at the top of the valence band, accounting for the SPH conduction. Interestingly, different from the literature, only 0.2% Sn doping in Fe2O3 significantly improves the PEC activity, while more Sn decreases it. The improved PEC activity is partially attributed to an increased band bending potential which facilitates the charge separation at the space charge region. The reduced activation energy barrier for SPH will facilitate the transport of photoexcited carriers for the enhanced PEC, which is of interest for further carrier dynamics study.

SCI ; EI

英语

其他

EPSRC[EP/L011700/1][EP/N004272/1] ; Royal Academy of Engineering[CiET1819_24] ; National Natural Science Foundation of China[21872116] ; Australian Research Council[FT160100207] ; U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Early Career Research Program[68278]

Chemistry ; Science & Technology - Other Topics ; Materials Science

Chemistry, Physical ; Nanoscience & Nanotechnology ; Materials Science, Multidisciplinary

WOS:000541745800041

AMER CHEMICAL SOC

20202908951485

Optical properties ; X ray absorption spectroscopy ; Calculations ; Activation energy ; Energy gap ; Hematite ; Oxide semiconductors ; Energy barriers ; Electronic structure ; Oxygen vacancies ; Pulsed laser deposition

Minerals:482.2 ; Thermodynamics:641.1 ; Semiconducting Materials:712.1 ; Light/Optics:741.1 ; Laser Applications:744.9 ; Physical Chemistry:801.4 ; Chemical Reactions:802.2 ; Mathematics:921 ; Atomic and Molecular Physics:931.3 ; Crystalline Solids:933.1

Web of Science

1.Xiamen Univ, State Key Lab Phys Chem Solid Surfaces, Coll Chem & Chem Engn, Xiamen 361005, Peoples R China
2.Univ Cambridge, Dept Mat Sci & Met, Cambridge CB3 0FS, England
3.Pacific Northwest Natl Lab, Phys & Computat Sci Directorate, Phys Sci Div, Richland, WA 99352 USA
4.Univ Elect Sci & Technol China, Sch Phys, Chengdu 610054, Peoples R China
5.Southern Univ Sci & Technol, Dept Phys, Shenzhen 518055, Guangdong, Peoples R China
6.Queensland Univ Technol, Ctr Mat Sci, Sch Chem & Phys, Brisbane, Qld 4001, Australia

Tian, C. M.,Li, W-W,Lin, Y. M.,et al. Electronic Structure, Optical Properties, and Photoelectrochemical Activity of Sn-Doped Fe2O3 Thin Films[J]. Journal of Physical Chemistry C,2020,124(23):12548-12558.

Tian, C. M..,Li, W-W.,Lin, Y. M..,Yang, Z. Z..,Wang, L..,...&Zhang, K. H. L..(2020).Electronic Structure, Optical Properties, and Photoelectrochemical Activity of Sn-Doped Fe2O3 Thin Films.Journal of Physical Chemistry C,124(23),12548-12558.

Tian, C. M.,et al."Electronic Structure, Optical Properties, and Photoelectrochemical Activity of Sn-Doped Fe2O3 Thin Films".Journal of Physical Chemistry C 124.23(2020):12548-12558.