Journal
JOURNAL OF CATALYSIS
Volume 304, Issue -, Pages 86-91Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcat.2013.04.014
Keywords
Solar water splitting; Photoelectrode; Hematite; Manganese oxide; Catalyst; Photovoltage; Photoelectrochemistry
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Funding
- Boston College
- National Science Foundation [DMR 1055762]
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To improve semiconductor-based water-splitting performance, one popular approach is to modify the electrode surface with catalysts. The strategy is to increase charge-transfer kinetics and, hence, to reduce overpotential requirements. Relatively underwhelming attention has been paid to how such surface treatments influence the nature of the semiconductor/solution interface so as to reduce photovoltage generated by the photoelectrode. Using atomic layer deposition-grown (ALD) MnOx on hematite (alpha-Fe2O3) as an example, here, we show that increased charge-transfer kinetics does not necessarily lead to improved overall performance. Compared to bare hematite, MnOx-decorated photoelectrode exhibits significant anodic on-set potential shift. The phenomenon is understood as a substantial reduction in photovoltage generation by hematite, and the origin is identified as Fermi-level pinning effect due to MnOx introduction. This work sheds light on the importance of maintaining band-edge pinning for semiconductor-based photoelectrochemical reactions. (C) 2013 Elsevier Inc. All rights reserved.
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