Ti doped hematite photoanodes: Protective coverage by titania overlayers

0574889 - ÚFCH JH 2024 RIV NL eng J - Journal Article
Imrich, Tomáš - Neumann-Spallart, M. - Krýsová, Hana - Tarábková, Hana - Nebel, Roman - Krýsa, J.
Ti doped hematite photoanodes: Protective coverage by titania overlayers.
Journal of Photochemistry and Photobiology A-Chemistry. Roč. 445, NOV 2023 (2023), č. článku 115026. ISSN 1010-6030. E-ISSN 1873-2666
R&D Projects: GA MŠMT(CZ) LM2023066; GA ČR(CZ) GA23-05266S; GA MŠMT(CZ) EF16_013/0001821
Grant - others:GA MŠk(CZ) CZ.02.1.01/0.0/0.0/16_013/0001821
Institutional support: RVO:61388955
Keywords : Dissolution rate * Hematite * Photocurrent * Ti doping * TiO overlayer 2 * electrochemistry
OECD category: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis)
Impact factor: 4.3, year: 2022
Method of publishing: Limited access

In this work, the photoresponse of Ti doped hematite electrodes was optimized by adjusting the thickness and the level of doping. The electrodes were then covered by a TiO2 overlayer by dip coating (DC) or by atomic layer deposition (ALD) to improve chemical stability. Coverage of hematite by a dip-coated sol–gel TiO2 film of thickness up to 135 nm resulted only in a small decrease in photocurrent (by about 30 %). A similar decrease in photocurrent (about 25 %) was observed after the coverage by a very thin (2 nm) ALD TiO2 film while the increase of the thickness to 8 nm led to almost complete suppression of photocurrent. This behaviour can be explained by the different morphology and structure of the overlayers. Although the surface morphology of sol–gel TiO2 films was very smooth and dense, penetration of such films by the electrolyte occurred even for a thickness of 135 nm. On the other hand, much thinner ALD TiO2 films (8 nm) exhibited almost no electrolyte penetration. Such different blocking properties of the two TiO2 overlayers are in direct agreement with the observed dissolution rate in acidic media – the better the blocking properties of an overlayer the better the chemical stability of stratified hematite/titania photoelectrode.
Permanent Link: https://hdl.handle.net/11104/0344817