Photoelectrochemical Behavior of n-Type GaAs(100) Electrodes Coated by a Single Layer of Graphene

Yang, F.; Nielander, Adam C.; Grimm, Ronald L.; Lewis, Nathan S.

doi:10.1021/acs.jpcc.6b00232

Cited by 24 publications

(13 citation statements)

References 40 publications

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“…The J ph of both photocathodes dropped rapidly by more than 90% within half an hour. Same as others' reports, the GaAs surface suffered from serious photocorrosion, oxidized quickly, and lost its catalytic capability (Figure S9a,b, Supporting Information). Significant Pt detachment was also observed due to the corrosion.…”

Section: Resultssupporting

confidence: 77%

“…Protection layers peels off during the reaction making GaAs difficult to protect . In near neutral solution GaAs photoanode and photocathode would both typically fail within 30 min . Practically, PEC devices need to have efficiencies of at least 10% with a lifetime longer than 10 years (≈30 000 on‐sun hours, i.e., ≈90 000 total operating hours) in order to be cost effective .…”

Section: Introductionmentioning

confidence: 99%

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Tailored TiO₂ Protection Layer Enabled Efficient and Stable Microdome Structured p‐GaAs Photoelectrochemical Cathodes

Cao

Kang

et al. 2020

Advanced Energy Materials

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Group III–V compound semiconductors are a promising group of materials for photoelectrochemical (PEC) applications. In this work, a metal assisted wet etching approach is adapted to acquiring a large‐area patterned microdome structure on p‐GaAs surface. In addition, atomic layer deposition is used to deposit a TiO2 protection layer with controlled thickness and crystallinity. Based on a PEC photocathode design, the optimal configuration achieves a photocurrent of −5 mA cm−2 under −0.8 V versus Ag/AgCl in a neutral pH electrolyte. The TiO2 coating with a particular degree of crystallization deposited via controlled temperature demonstrates a superior stability over amorphous coating, enabling a remarkably stable operation, for as long as 60 h. The enhanced charge separation induced by favorable band alignment between GaAs and TiO2 contributes simultaneously to the elevated solar conversion efficiency. This approach provides a promising solution to further development of group III–V compounds and other photoelectrodes with high efficiency and excellent durability for solar fuel generation.

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Section: Resultssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Tailored TiO₂ Protection Layer Enabled Efficient and Stable Microdome Structured p‐GaAs Photoelectrochemical Cathodes

Cao

Kang

et al. 2020

Advanced Energy Materials

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“…In striving to develop efficient and stable PEC systems, researchers have employed a variety of semiconductor types as photoelectrodes, including silicon, metal oxides, and III-Vs. − Metal oxides have demonstrated the greatest stability under water oxidation conditions, however, they typically exhibit large bandgaps and/or short minority-carrier diffusion lengths which have inhibited achieving high solar-to-hydrogen efficiency . III–V semiconductors, in contrast, can cover a wide range of bandgaps, often have high charge-carrier mobilities and diffusion lengths, and are among the best candidates for high efficiency photoelectrodes, especially as the top subcell material in a tandem cell design. ,, Although III–V semiconductors can enable systems of high solar-to-hydrogen efficiency, they generally suffer from corrosion in aqueous electrolytes under anodic conditions because the self-oxidation potentials of these materials are more negative than the water oxidation potential. − One strategy employed to mitigate photocorrosion of III–V photoelectrodes is to deposit a conformal thin film of a metal or metal oxide on the semiconductor surface as a protective barrier layer against chemical attack, which in some cases can also serve as an OER catalyst. − …”

Section: Introductionmentioning

confidence: 99%

Investigation of n-GaAs Photoanode Corrosion in Acidic Media with Various Thin Ir Cocatalyst Layers

Pishgar

Mulvehill

Gulati

et al. 2021

ACS Appl. Energy Mater.

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n-GaAs is a well-developed III–V semiconductor with excellent light absorption and charge-transport properties, making it a promising candidate for an efficient photoanode. However, strong photocorrosion under anodic bias in aqueous electrolyte prohibits this semiconductor from having durable as well as efficient photoelectrochemical performance. In this work, the photocorrosion process of n-GaAs in acidic media was monitored via in situ UV–vis spectroscopic analysis of the dissolved elements in solution, with additional insight provided by SEM imaging and XPS surface analysis. A strong dependence of the current density vs potential behavior and associated photocorrosion was correlated to the n-type doping density, with the transition into degenerate-like behavior yielding distinctly different photoelectrochemical and corrosion behavior. The photoanode behavior in acid was also investigated with thin surface layers of the acid-stable water oxidation catalyst Ir. Galvanic displacement was used to produce conformal thin films of Ir on n-GaAs, which was compared to films of Ir spin-coated from chemical precursors. In-situ UV–vis spectroscopy showed short-term decreases in the corrosion faradaic efficiency from the Ir films, but none provided sufficient protection to prevent GaAs photoetching from eventually becoming the dominant electrochemical pathway. The disparate nature of each Ir film is discussed to explain the observed differences in surface chemistry and morphology after photoanodic operation.

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“…The protective metal film must be sufficiently thin (≈2 nm) to limit spurious light absorption, and without pinholes. Examples of this architecture date back from the 1980s, [ 5 ] and current efforts feature improved devices made available by advanced film deposition methods, including for example e‐beam deposition of Ni, [ 6 ] atomic layer deposition of TiO 2 , [ 7 ] electrodeposition of Co, [ 8 ] and graphene [ 9 ] among others.…”

Section: Introductionmentioning

confidence: 99%

Photoelectrochemistry of Self‐Limiting Electrodeposition of Ni Film onto GaAs

Ahmed

Zheng

et al. 2020

Small

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Gallium arsenide (GaAs) provides a suitable bandgap (1.43 eV) for solar spectrum absorption and allows a larger photovoltage compared to silicon, suggesting great potential as a photoanode toward water splitting. Photocorrosion under water oxidation condition, however, leads to decomposition or the formation of an insulating oxide layer, which limits the photoelectrochemical performance and stability of GaAs. In this work, a self‐limiting electrodeposition method of Ni on GaAs is reported to either generate ultra‐thin continuous film or nanoislands with high particle density by controlling deposition time. The self‐limiting growth mechanism is validated by potential transients, X‐ray photoelectron spectroscopy composition and depth profile measurements. This deposition method exhibits a rapid nucleation, forms an initial metallic layer followed by a hydroxide/oxyhydroxide nanofilm on the GaAs surface and is independent of layer thickness versus deposition time when coalescence is reached. A photocurrent up to 8.9 mA cm−2 with a photovoltage of 0.11 V is obtained for continuous ultrathin films, while a photocurrent density of 9.2 mA cm−2 with a photovoltage of 0.50 V is reached for the discontinuous nanoislands layers in an aqueous solution containing the reversible redox couple K3Fe(CN)6/K4Fe(CN)6.

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Photoelectrochemical Behavior of n-Type GaAs(100) Electrodes Coated by a Single Layer of Graphene

Abstract: A series of redox couples that have an effective potential ranging from -0.87 V to 0.23 V vs the saturated calomel electrode (SCE) was used in the electrochemical studies. The preparation and purification of chemicals were exactly the same as reported previously.

Cited by 24 publications

References 40 publications

Tailored TiO₂ Protection Layer Enabled Efficient and Stable Microdome Structured p‐GaAs Photoelectrochemical Cathodes

Tailored TiO₂ Protection Layer Enabled Efficient and Stable Microdome Structured p‐GaAs Photoelectrochemical Cathodes

Investigation of n-GaAs Photoanode Corrosion in Acidic Media with Various Thin Ir Cocatalyst Layers

Photoelectrochemistry of Self‐Limiting Electrodeposition of Ni Film onto GaAs

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Photoelectrochemical Behavior of n-Type GaAs(100) Electrodes Coated by a Single Layer of Graphene

Abstract: A series of redox couples that have an effective potential ranging from -0.87 V to 0.23 V vs the saturated calomel electrode (SCE) was used in the electrochemical studies. The preparation and purification of chemicals were exactly the same as reported previously.

Cited by 24 publications

References 40 publications

Tailored TiO2 Protection Layer Enabled Efficient and Stable Microdome Structured p‐GaAs Photoelectrochemical Cathodes

Tailored TiO2 Protection Layer Enabled Efficient and Stable Microdome Structured p‐GaAs Photoelectrochemical Cathodes

Investigation of n-GaAs Photoanode Corrosion in Acidic Media with Various Thin Ir Cocatalyst Layers

Photoelectrochemistry of Self‐Limiting Electrodeposition of Ni Film onto GaAs

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Product

Resources

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Tailored TiO₂ Protection Layer Enabled Efficient and Stable Microdome Structured p‐GaAs Photoelectrochemical Cathodes

Tailored TiO₂ Protection Layer Enabled Efficient and Stable Microdome Structured p‐GaAs Photoelectrochemical Cathodes