Abstract
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.
Original language | English (US) |
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Pages (from-to) | 218-224 |
Number of pages | 7 |
Journal | Surface Science |
Volume | 617 |
DOIs | |
State | Published - Nov 2013 |
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry
Keywords
- Density functional theory
- Doping
- Mixed oxides
- Photocatalysis
- Water-splitting