Journal
SURFACE SCIENCE
Volume 617, Issue -, Pages 218-224Publisher
ELSEVIER
DOI: 10.1016/j.susc.2013.07.023
Keywords
Photocatalysis; Density functional theory; Doping; Mixed oxides; Water-splitting
Categories
Funding
- Air Force Office of Scientific Research
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Improving photochemical water oxidation processes on sunlight absorbing materials requires understanding the photoelectrode-solution interface. We use ab initio density functional theory (DFT) + U to investigate the structure and energetics of water adsorbed on MnO:ZnO(001), a potential photoanode material we previously identified as having suitable band gaps and band edge placements for visible light induced water splitting. Our calculations show that there is a preference for molecular adsorption at water coverages of less than half a monolayer (ML). At higher coverages, cooperative water-water interactions facilitate water dissociation at the interface. We find that the work function is very sensitive to water dipole orientation and/or presence of hydroxyls on the surface. The computed phase diagram reveals the surface to be fairly hydrophilic with a preference for the first water ML to be 33% dissociated at 0.75 ML, 50% dissociated at 1 ML, and 50% dissociated at 2 ML water coverage under various conditions away from water-poor conditions. (C) 2013 Elsevier B.V. All rights reserved.
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