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Better Together: Ilmenite/Hematite Junctions for Photoelectrochemical Water Oxidation
- Source :
- ACS Applied Materials and Interfaces 12(2020)42, 47435-47446, 'ACS Applied Materials & Interfaces ', vol: 12, pages: 47435-47446 (2020), ACS Applied Materials & Interfaces, ACS applied materials & interfaces, 12 (2020): 47435–47446. doi:10.1021/acsami.0c122750, info:cnr-pdr/source/autori:Berardi, Serena; Kesavan, Jagadesh Kopula; Amidani, Lucia; Meloni, Elia Marek; Marelli, Marcello; Boscherini, Federico; Caramori, Stefano; Pasquini, Luca/titolo:Better Together: Ilmenite%2FHematite Junctions for Photoelectrochemical Water Oxidation/doi:10.1021%2Facsami.0c122750/rivista:ACS applied materials & interfaces (Print)/anno:2020/pagina_da:47435/pagina_a:47446/intervallo_pagine:47435–47446/volume:12
- Publication Year :
- 2020
-
Abstract
- Hematite (alpha-Fe2O3) is an earth-abundant indirect n-type semiconductor displaying a band gap of about 2.2 eV, useful for collecting a large fraction of visible photons, with frontier energy levels suitably aligned for carrying out the photo-electrochemical water oxidation reaction under basic conditions. The modification of hematite mesoporous thin- film photoanodes with Ti(IV), as well as their functionalization with an oxygen-evolving catalyst, leads to a 6-fold increase in photocurrent density with respect to the unmodified electrode. In order to provide a detailed understanding of this behavior, we report a study of Ti-containing phases within the mesoporous film structure. Using X-ray absorption fine structure and high-resolution transmission electron microscopy coupled with electron energy loss spectroscopy, we find that Ti(IV) ions are incorporated within ilmenite (FeTiO3) near-surface layers, thus modifying the semiconductor-electrolyte interface. To the best of our knowledge, this is the first time that an FeTiO3/-Fe2O3 composite is used in a photoelectrochemical setup for water oxidation. In fact, previous studies of Ti(IV)modified hematite photoanodes reported the formation of pseudobrookite (Fe2TiO5) at the surface. By means of transient absorption spectroscopy, transient photocurrent experiments, and electrochemical impedance spectroscopy, we show that the formation of the Fe2O3/FeTiO3 interface passivates deep traps at the surface and induces a large density of donor levels, resulting in a strong depletion field that separates electron and holes, favoring hole injection in the electrolyte. Our results provide the identification of a phase coexistence with enhanced photoelectrochemical performance, allowing for the rational design of new photoanodes with improved kinetics.
- Subjects :
- Pseudobrookite
Materials science
Band gap
Photoelectrochemistry
Hematite
02 engineering and technology
engineering.material
010402 general chemistry
01 natural sciences
PE4_15
hematite
photoelectrochemistry
Transient Absorption Spectroscopy
titanium
EXAFS
electron microscopy
transient absorption spectroscopy
electrochemical impedance spectroscopy
heterointerface
oxygen evolution catalyst
General Materials Science
Electron Microscopy
PE5_6
Absorption (electromagnetic radiation)
PE5_3
Photocurrent
Titanium
Electron energy loss spectroscopy
Heterointerface
Ambientale
021001 nanoscience & nanotechnology
0104 chemical sciences
Dielectric spectroscopy
Chemical engineering
visual_art
electrochemical impedance spectroscopy, heterointerface
engineering
visual_art.visual_art_medium
0210 nano-technology
Oxygen Evolution Catalyst
Research Article
Subjects
Details
- Language :
- English
- ISSN :
- 19448244
- Database :
- OpenAIRE
- Journal :
- ACS Applied Materials and Interfaces 12(2020)42, 47435-47446, 'ACS Applied Materials & Interfaces ', vol: 12, pages: 47435-47446 (2020), ACS Applied Materials & Interfaces, ACS applied materials & interfaces, 12 (2020): 47435–47446. doi:10.1021/acsami.0c122750, info:cnr-pdr/source/autori:Berardi, Serena; Kesavan, Jagadesh Kopula; Amidani, Lucia; Meloni, Elia Marek; Marelli, Marcello; Boscherini, Federico; Caramori, Stefano; Pasquini, Luca/titolo:Better Together: Ilmenite%2FHematite Junctions for Photoelectrochemical Water Oxidation/doi:10.1021%2Facsami.0c122750/rivista:ACS applied materials & interfaces (Print)/anno:2020/pagina_da:47435/pagina_a:47446/intervallo_pagine:47435–47446/volume:12
- Accession number :
- edsair.doi.dedup.....1dd8e7cac9cdc4945354cddd0998f853