Identification of lone-pair surface states on indium oxide
Indium oxide is widely used as a transparent electrode in optoelectronic devices and as a photocatalyst with activity for reduction of CO 2 . However, very little is known about the structural and electronic properties of its surfaces, particularly those prepared under reducing conditions. In this r...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Journal article |
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American Chemical Society
2018
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| _version_ | 1826294242482323456 |
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| author | Davies, D Walsh, A Mudd, J McConville, C Regoutz, A Kahk, J Payne, D Dhanak, V Hesp, D Pussi, K Lee, T Egdell, R Zhang, K |
| author_facet | Davies, D Walsh, A Mudd, J McConville, C Regoutz, A Kahk, J Payne, D Dhanak, V Hesp, D Pussi, K Lee, T Egdell, R Zhang, K |
| author_sort | Davies, D |
| collection | OXFORD |
| description | Indium oxide is widely used as a transparent electrode in optoelectronic devices and as a photocatalyst with activity for reduction of CO 2 . However, very little is known about the structural and electronic properties of its surfaces, particularly those prepared under reducing conditions. In this report, directional "lone-pair" surface states associated with filled 5s 2 orbitals have been identified on vacuum-annealed In 2 O 3 (111) through a combination of hard and soft X-ray photoemission spectroscopy and density functional theory calculations. The lone pairs reside on indium ad-atoms in a formal +1 oxidation state, each of which traps two electrons into a localized hybrid orbital protruding away from the surface and lying just above the valence band maximum in photoemission spectra. The third electron associated with the ad-atoms is delocalized into the conduction band, thus producing the surface electron accumulation layer identified previously on vacuum-annealed In 2 O 3 (111) (1 × 1) surfaces. The surface structure is further supported by low-energy electron diffraction, but there is no chemical shift in indium core level X-ray photoelectron spectra between surface In(I) ad-atoms and bulk In(III). The 5s 2 lone pairs confer Lewis basicity on the surface In sites and may have a pronounced impact on the catalytic or photocatalytic activity of reduced In 2 O 3 . |
| first_indexed | 2024-03-07T03:42:37Z |
| format | Journal article |
| id | oxford-uuid:be6ac665-f74b-4e72-b1fa-b9f46418f057 |
| institution | University of Oxford |
| last_indexed | 2024-03-07T03:42:37Z |
| publishDate | 2018 |
| publisher | American Chemical Society |
| record_format | dspace |
| spelling | oxford-uuid:be6ac665-f74b-4e72-b1fa-b9f46418f0572022-03-27T05:39:16ZIdentification of lone-pair surface states on indium oxideJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:be6ac665-f74b-4e72-b1fa-b9f46418f057Symplectic Elements at OxfordAmerican Chemical Society2018Davies, DWalsh, AMudd, JMcConville, CRegoutz, AKahk, JPayne, DDhanak, VHesp, DPussi, KLee, TEgdell, RZhang, KIndium oxide is widely used as a transparent electrode in optoelectronic devices and as a photocatalyst with activity for reduction of CO 2 . However, very little is known about the structural and electronic properties of its surfaces, particularly those prepared under reducing conditions. In this report, directional "lone-pair" surface states associated with filled 5s 2 orbitals have been identified on vacuum-annealed In 2 O 3 (111) through a combination of hard and soft X-ray photoemission spectroscopy and density functional theory calculations. The lone pairs reside on indium ad-atoms in a formal +1 oxidation state, each of which traps two electrons into a localized hybrid orbital protruding away from the surface and lying just above the valence band maximum in photoemission spectra. The third electron associated with the ad-atoms is delocalized into the conduction band, thus producing the surface electron accumulation layer identified previously on vacuum-annealed In 2 O 3 (111) (1 × 1) surfaces. The surface structure is further supported by low-energy electron diffraction, but there is no chemical shift in indium core level X-ray photoelectron spectra between surface In(I) ad-atoms and bulk In(III). The 5s 2 lone pairs confer Lewis basicity on the surface In sites and may have a pronounced impact on the catalytic or photocatalytic activity of reduced In 2 O 3 . |
| spellingShingle | Davies, D Walsh, A Mudd, J McConville, C Regoutz, A Kahk, J Payne, D Dhanak, V Hesp, D Pussi, K Lee, T Egdell, R Zhang, K Identification of lone-pair surface states on indium oxide |
| title | Identification of lone-pair surface states on indium oxide |
| title_full | Identification of lone-pair surface states on indium oxide |
| title_fullStr | Identification of lone-pair surface states on indium oxide |
| title_full_unstemmed | Identification of lone-pair surface states on indium oxide |
| title_short | Identification of lone-pair surface states on indium oxide |
| title_sort | identification of lone pair surface states on indium oxide |
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