n-Fe2O3 to N+-TiO2 Heterojunction Photoanode for Photoelectrochemical Water Oxidation
- 10 June 2015
- journal article
- research article
- Published by American Chemical Society (ACS) in ACS Applied Materials & Interfaces
- Vol. 7 (24), 13314-13321
- https://doi.org/10.1021/acsami.5b01489
Abstract
To improve the performance of the thin hematite photoanode for photoelectrochemical water oxidation, in this work, an nN(+) α-Fe2O3 (hematite)-TiO2 heterojunction photoanode is constructed on fluorine-doped tin oxide substrate to establish a built-in field in the space charge region for facilitating the charge separation in the hematite layer. Charge distribution in the hematite-TiO2 heterostructure is investigated using Kelvin probe force microscopy, which confirms the improvement of charge separation in hematite layer by the formation of energy-matched nN(+) α-Fe2O3-TiO2 heterojunction. Compared to the hematite photoanode, an eightfold enhancement of the photocurrent density at 1.23 V versus reversible hydrogen electrode is measured in the hematite-TiO2 heterojunction photoanode. By using hydrogen peroxide as a hole scavenger, it demonstrates that both charge separation and charge injection efficiencies in the hematite-TiO2 heterojunction photoanode are superior to those in the hematite photoanode. It results from the significant suppressions of the charge recombinations occurring within the hematite layer as well as at the interface of photoelectrode and electrolyte by the formation of the nN(+) α-Fe2O3-TiO2 heterojunction.Keywords
Funding Information
- Ministry of Science and Technology, Taiwan (MOST 102-2221-E-006-215-MY3, MOST 103-2221-E-006-245-MY3)
- Ministry of Education, Taiwan
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