Elucidating the electronic structure of CuWO4 thin films for Enhanced photoelectrochemical water splitting

C.M. Tian, M. Jiang, D. Tang, L. Qiao, H.Y. Xiao, F.E. Oropeza, J.P. Hofmann, E.J.M. Hensen, A. Tadich, W. Li, D.C. Qi, K.H.L. Zhang (Corresponding author)

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

6 Citaties (Scopus)

Uittreksel

CuWO 4 is an n-type oxide semiconductor with a bandgap of 2.2 eV which exhibits great potential for photoelectrochemical (PEC) conversion of solar energy into chemical fuels. However, the photocurrent achieved so far is limited to ∼0.3 mA cm -2 at +1.23 V vs. reversible hydrogen electrode (RHE). Possible limiting factors include slow surface reaction kinetics, poor charge carrier mobility and/or presence of surface defect states. A detailed understanding of the fundamental electronic structure and its correlation with PEC activity is of significant importance for devising strategies for further improvements. In this work, we have synthesized CuWO 4 thin films showing a record photocurrent density of 0.50 mA cm -2 at +1.23 V vs. RHE. Importantly, we have used a synergistic combination of photoemission spectroscopy, X-ray absorption spectroscopy and density functional theory (DFT) to unravel the electronic structure of CuWO 4 . Our results show that the valence band (VB) consists of strongly hybridized states of O 2p 6 and Cu 3d 9 , while the bottom of the conduction band (CB) is primarily composed of unoccupied Cu 3d states. The localized nature of the Cu 3d state leads to the low charge carrier mobility and the localization of the photo-excited electrons to the CB. The combined experimental and theoretical results also indicate that CuWO 4 is better described as having a direct but d-d forbidden optical bandgap, leading to a low absorption coefficient for visible light. Furthermore, the implication of the electronic structure on its PEC characteristics and strategies for further improvements by adding Co 3 O 4 as a co-catalyst or surface layer to increase the interfacial band bending to facilitate photo-carriers transport, are discussed.

Originele taal-2Engels
Pagina's (van-tot)11895-11907
Aantal pagina's13
TijdschriftJournal of Materials Chemistry A
Volume7
Nummer van het tijdschrift19
DOI's
StatusGepubliceerd - 12 apr 2019

Vingerafdruk

Electronic structure
Carrier mobility
Conduction bands
Charge carriers
Photocurrents
Thin films
Water
Hydrogen
Electrodes
X ray absorption spectroscopy
Carrier transport
Surface defects
Optical band gaps
Surface reactions
Photoelectron spectroscopy
Valence bands
Reaction kinetics
Solar energy
Density functional theory
Energy gap

Citeer dit

Tian, C. M., Jiang, M., Tang, D., Qiao, L., Xiao, H. Y., Oropeza, F. E., ... Zhang, K. H. L. (2019). Elucidating the electronic structure of CuWO4 thin films for Enhanced photoelectrochemical water splitting. Journal of Materials Chemistry A, 7(19), 11895-11907. https://doi.org/10.1039/C8TA12070F
Tian, C.M. ; Jiang, M. ; Tang, D. ; Qiao, L. ; Xiao, H.Y. ; Oropeza, F.E. ; Hofmann, J.P. ; Hensen, E.J.M. ; Tadich, A. ; Li, W. ; Qi, D.C. ; Zhang, K.H.L. / Elucidating the electronic structure of CuWO4 thin films for Enhanced photoelectrochemical water splitting. In: Journal of Materials Chemistry A. 2019 ; Vol. 7, Nr. 19. blz. 11895-11907.
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Tian, CM, Jiang, M, Tang, D, Qiao, L, Xiao, HY, Oropeza, FE, Hofmann, JP, Hensen, EJM, Tadich, A, Li, W, Qi, DC & Zhang, KHL 2019, 'Elucidating the electronic structure of CuWO4 thin films for Enhanced photoelectrochemical water splitting', Journal of Materials Chemistry A, vol. 7, nr. 19, blz. 11895-11907. https://doi.org/10.1039/C8TA12070F

Elucidating the electronic structure of CuWO4 thin films for Enhanced photoelectrochemical water splitting. / Tian, C.M.; Jiang, M.; Tang, D.; Qiao, L.; Xiao, H.Y.; Oropeza, F.E.; Hofmann, J.P.; Hensen, E.J.M.; Tadich, A.; Li, W.; Qi, D.C.; Zhang, K.H.L. (Corresponding author).

In: Journal of Materials Chemistry A, Vol. 7, Nr. 19, 12.04.2019, blz. 11895-11907.

Onderzoeksoutput: Bijdrage aan tijdschriftTijdschriftartikelAcademicpeer review

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T1 - Elucidating the electronic structure of CuWO4 thin films for Enhanced photoelectrochemical water splitting

AU - Tian, C.M.

AU - Jiang, M.

AU - Tang, D.

AU - Qiao, L.

AU - Xiao, H.Y.

AU - Oropeza, F.E.

AU - Hofmann, J.P.

AU - Hensen, E.J.M.

AU - Tadich, A.

AU - Li, W.

AU - Qi, D.C.

AU - Zhang, K.H.L.

PY - 2019/4/12

Y1 - 2019/4/12

N2 - CuWO 4 is an n-type oxide semiconductor with a bandgap of 2.2 eV which exhibits great potential for photoelectrochemical (PEC) conversion of solar energy into chemical fuels. However, the photocurrent achieved so far is limited to ∼0.3 mA cm -2 at +1.23 V vs. reversible hydrogen electrode (RHE). Possible limiting factors include slow surface reaction kinetics, poor charge carrier mobility and/or presence of surface defect states. A detailed understanding of the fundamental electronic structure and its correlation with PEC activity is of significant importance for devising strategies for further improvements. In this work, we have synthesized CuWO 4 thin films showing a record photocurrent density of 0.50 mA cm -2 at +1.23 V vs. RHE. Importantly, we have used a synergistic combination of photoemission spectroscopy, X-ray absorption spectroscopy and density functional theory (DFT) to unravel the electronic structure of CuWO 4 . Our results show that the valence band (VB) consists of strongly hybridized states of O 2p 6 and Cu 3d 9 , while the bottom of the conduction band (CB) is primarily composed of unoccupied Cu 3d states. The localized nature of the Cu 3d state leads to the low charge carrier mobility and the localization of the photo-excited electrons to the CB. The combined experimental and theoretical results also indicate that CuWO 4 is better described as having a direct but d-d forbidden optical bandgap, leading to a low absorption coefficient for visible light. Furthermore, the implication of the electronic structure on its PEC characteristics and strategies for further improvements by adding Co 3 O 4 as a co-catalyst or surface layer to increase the interfacial band bending to facilitate photo-carriers transport, are discussed.

AB - CuWO 4 is an n-type oxide semiconductor with a bandgap of 2.2 eV which exhibits great potential for photoelectrochemical (PEC) conversion of solar energy into chemical fuels. However, the photocurrent achieved so far is limited to ∼0.3 mA cm -2 at +1.23 V vs. reversible hydrogen electrode (RHE). Possible limiting factors include slow surface reaction kinetics, poor charge carrier mobility and/or presence of surface defect states. A detailed understanding of the fundamental electronic structure and its correlation with PEC activity is of significant importance for devising strategies for further improvements. In this work, we have synthesized CuWO 4 thin films showing a record photocurrent density of 0.50 mA cm -2 at +1.23 V vs. RHE. Importantly, we have used a synergistic combination of photoemission spectroscopy, X-ray absorption spectroscopy and density functional theory (DFT) to unravel the electronic structure of CuWO 4 . Our results show that the valence band (VB) consists of strongly hybridized states of O 2p 6 and Cu 3d 9 , while the bottom of the conduction band (CB) is primarily composed of unoccupied Cu 3d states. The localized nature of the Cu 3d state leads to the low charge carrier mobility and the localization of the photo-excited electrons to the CB. The combined experimental and theoretical results also indicate that CuWO 4 is better described as having a direct but d-d forbidden optical bandgap, leading to a low absorption coefficient for visible light. Furthermore, the implication of the electronic structure on its PEC characteristics and strategies for further improvements by adding Co 3 O 4 as a co-catalyst or surface layer to increase the interfacial band bending to facilitate photo-carriers transport, are discussed.

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