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Published August 21, 2014 | Published + Supplemental Material
Journal Article Open

Optical in Situ Study of InP(100) Surface Chemistry: Dissociative Adsorption of Water and Oxygen

Abstract

Semiconductors designated for solar water-splitting need to be simultaneously stable and efficient in the charge transfer over the interface to the aqueous electrolyte. Although InP(100) has been employed as photocathode for several decades, no experimental data on its initial interaction with water is available. We study reaction mechanisms of well-defined surfaces with water and oxygen employing photoelectron and in situ reflection anisotropy spectroscopy. Our findings show that reaction path and stability differ significantly with atomic surface reconstruction. While the mixed-dimer In-rich surface exhibits dissociative water adsorption featuring In–O–P rather than unfavorable In–O–In bond topologies, the H-terminated, P-rich surface reconstruction is irreversibly removed. Oxygen exposure attacks the In-rich surface more efficiently and additionally modifies, unlike water exposure, bulk-related optical transitions. Hydroxyl is not observed, which suggests a dehydrogenation of adsorbed species already at ambient temperature. Our findings may benefit the design of InP(100) surfaces for photoelectrochemical water splitting.

Additional Information

© 2014 American Chemical Society. ACS AuthorChoice - This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes. Received: March 25, 2014. Revised: July 30, 2014. Published: July 30, 2014. M.M.M. acknowledges Studienstiftung des deutschen Volkes for his scholarship. This material is based upon work performed by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, as follows: parts of the organization of the work, of the discussion, as well as of the manuscript wording and composition were supported through the Office of Science of the U.S. Department of Energy under Award DESC0004993.

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