Ab initio modeling of water-semiconductor interfaces for direct solar-to-chemical energy conversion

Wood, Brandon C.; Ogitsu, Tadashi; Schwegler, Eric

doi:10.1117/12.860770

Cited by 4 publications

(6 citation statements)

References 9 publications

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“…2a) and the Ga 3d peak (Fig. 4,6,15,16,27,66 It was estimated that the presence of P-H bonding can increase the water adsorption energy by 0.23-0.35 eV at a coverage of one monolayer. Because these changes in the Ga 2p 3/2 spectra are more pronounced than those in the Ga 3d spectra, we conclude that the oxidation and hydroxylation mainly occur at the outmost atomic layers at RT, since the Ga 2p spectra are more surface-sensitive compared to the Ga 3d spectra.…”

Section: Water Dissociationmentioning

confidence: 99%

Distinct and dramatic water dissociation on GaP(111) tracked by near-ambient pressure X-ray photoelectron spectroscopy

Zhang

Ptasińska

2015

Phys. Chem. Chem. Phys.

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Water adsorption and dissociation on a GaP(111) crystal surface are investigated using near-ambient pressure X-ray photoelectron spectroscopy (NAP XPS) in a wide range of pressures (∼10(-10)-5 mbar) and temperatures (∼300-773 K). Dynamic changes in chemical evolution at the H2O/GaP(111) interface are reflected in Ga 2p3/2, O 1s, and P 2p spectra. In the pressure-dependent study performed at room temperature, an enhancement of surface Ga hydroxylation and oxidation with an increase in H2O pressure is observed. In the temperature-dependent study performed at elevated pressures, two distinct regions can be defined in which drastic changes occur in the surface chemistry. Below 673 K, the surface Ga hydroxylation and oxidation progress continuously. However, above 673 K, a large-scale conversion of surface O-Ga-OH species into non-stoichiometric Ga hydroxide along with oxidation of surface P atoms occurs through an intermediate state. The NAP XPS technique enabled us to experimentally track the chemistry at the H2O/GaP interface under near-realistic conditions, thereby providing evidence to compare with recent theoretical efforts to improve the understanding of water-splitting mechanisms and photo-corrosion on semiconductor surfaces.

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Section: Water Dissociationmentioning

confidence: 99%

Distinct and dramatic water dissociation on GaP(111) tracked by near-ambient pressure X-ray photoelectron spectroscopy

Zhang

Ptasińska

2015

Phys. Chem. Chem. Phys.

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“…semiconductors InP and GaP has been subject of several theoretical investigations [11][12][13], but experimental data only exists for InP(110) [14,15] and not for GaP to our knowledge.…”

Section: Introductionmentioning

confidence: 99%

“…Model experiments in the literature involved water adsorption in ultra-high vacuum (UHV) to gain insight into the surface modifications of semiconductors induced by H 2 O [9,10], as typical surface science tools such as photoelectron spectroscopy cannot be applied in a fully realistic liquid environment. The initial contact between water and the III-V semiconductors InP and GaP has been subject of several theoretical investigations [11,12,13], but experimental data only exists for InP(110) [14,15] and not for GaP to our knowledge.…”

Section: Introductionmentioning

confidence: 99%

The interface of GaP(100) and H₂O studied by photoemission and reflection anisotropy spectroscopy

et al. 2013

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We study the initial interaction of adsorbed H 2 O with P-rich and Ga-rich GaP(100) surfaces. Atomically well defined surfaces are prepared by metal-organic vapour phase epitaxy and transferred contamination-free to ultra-high vacuum, where water is adsorbed at room temperature. Finally, the surfaces are annealed in vapour phase ambient. During all steps, the impact on the surface properties is monitored with in-situ reflection anisotropy spectroscopy (RAS). Photoelectron spectroscopy and lowenergy electron diffraction are applied for further in-system studies. After exposure up to saturation of the RA spectra, the Ga-rich (2 × 4) surface reconstruction exhibits a sub-monolayer coverage in form of a mixture of molecularly and dissociatively adsorbed water. For the p(2 × 2)/c(4 × 2) P-rich surface reconstruction, a new c(2 × 2) superstructure forms upon adsorption and the uptake of adsorbate is significantly reduced when compared to the Ga-rich surface. Our findings show that microscopic surface reconstructions of GaP(100) greatly impact the mechanism of initial interface formation with water, which could benefit the design of e.g. photoelectrochemical water splitting devices.

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“…This study specifically takes advantage of expanded computational capabilities at the Lawrence Livermore National Laboratories (LLNL), as well as state-of-the-art ex-situ and new in-situ interface characterization capabilities being developed by University of Nevada at Las Vegas (UNLV) at the Lawrence Berkeley Advanced-Light-Source facility and at UNLV. New advances in ab-initio theoretical models of PEC materials and interfaces being developed at LLNL [13,14,15] are a key part of this effort. First principles dynamic models of the PEC interface are been constructed based on III-V semiconductors, specifically exploring effects of O, H and OH termination ; and important correlations between surface morphology and interaction with interfacial water molecules are being established.…”

Section: Pec Working Group Activities and Progressmentioning

confidence: 99%

Research Highlights from the U.S. Department of Energy’s Working Group on Photoelectrochemical Hydrogen Production

2011

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The US Department of Energy (DOE) hydrogen production research and development portfolio focuses on low-cost, highly efficient and environmentally friendly production technologies based on diverse, domestic resources. Within the DOE, work on hydrogen production technologies integrates basic and applied research, as well as technology development and demonstration. The integration of basic and applied research is of particular importance in "transformational" production technologies, such as photoelectrochemical (PEC) hydrogen production, where scientific advances are needed for achieving the long-term DOE performance and cost targets. In the case of renewable hydrogen production via PEC solar water splitting, high solar-to-hydrogen conversion efficiency has been demonstrated to date on the laboratory scale, but only with high-cost, low-durability material systems. In order to identify and develop the appropriate highefficiency, low-cost, durable and scalable PEC material systems, research and development efforts in the DOE EERE (Energy Efficiency and Renewable Energy) Office have keyed in on specific focus areas, including: 1) the engineering of solar energy absorption properties in PEC semiconductor materials, such as the bandgap lowering in stable metal oxides as well as bandgap raising in nanostructured sulfide catalysts; 2) the engineering of PEC solid-liquid interfaces for optimal reaction rates and stability, such as surface nitrogenation in III-V semiconductor systems; 3) the standardization of PEC measurement and reporting methodologies, using national and international peer-review process, for facilitating research progress; and 4) the design and analysis of integrated PEC device and system configurations for scalable hydrogen production. As described in this presentation, all of these research and development areas rely heavily on collaborative efforts among academia, industry and national laboratory partners, utilizing state of the art resources in materials theory, synthesis, characterization and analysis. The collaboration extends nationally among research programs supported by the DOE EERE as well as Office of Science; and internationally via networking through the International Energy Agency's Hydrogen Implementation Agreement Annex-26.

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Ab initio modeling of water-semiconductor interfaces for direct solar-to-chemical energy conversion

Cited by 4 publications

References 9 publications

Distinct and dramatic water dissociation on GaP(111) tracked by near-ambient pressure X-ray photoelectron spectroscopy

Distinct and dramatic water dissociation on GaP(111) tracked by near-ambient pressure X-ray photoelectron spectroscopy

The interface of GaP(100) and H₂O studied by photoemission and reflection anisotropy spectroscopy

Research Highlights from the U.S. Department of Energy’s Working Group on Photoelectrochemical Hydrogen Production

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Ab initio modeling of water-semiconductor interfaces for direct solar-to-chemical energy conversion

Cited by 4 publications

References 9 publications

Distinct and dramatic water dissociation on GaP(111) tracked by near-ambient pressure X-ray photoelectron spectroscopy

Distinct and dramatic water dissociation on GaP(111) tracked by near-ambient pressure X-ray photoelectron spectroscopy

The interface of GaP(100) and H2O studied by photoemission and reflection anisotropy spectroscopy

Research Highlights from the U.S. Department of Energy’s Working Group on Photoelectrochemical Hydrogen Production

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The interface of GaP(100) and H₂O studied by photoemission and reflection anisotropy spectroscopy