Photoelectrochemical Properties of InGaN for H<sub>2</sub> Generation from Aqueous Water

Fujii, K.; Kusakabe, Kazuhide; Ohkawa, Kazuhiro

doi:10.1143/jjap.44.7433

Cited by 85 publications

(60 citation statements)

References 11 publications

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“…Furthermore, alloys of InN and GaN have recently attracted interest for use in multijunction photovoltaic devices [10][11][12] and as photoelectrodes for water splitting. [13][14][15][16][17][18][19][20] In photochemical water splitting, the InGaN semiconductor absorbs sunlight and thereby produces electrons and holes, which drives the water-splitting reaction. Successful photoelectrode materials must fulfill at least the following three criteria: (i) The band gap must be such that a significant fraction of the solar spectrum is absorbed; (ii) the conduction band (CB) and valence band (VB) must straddle the redox potential of hydrogen and water; and (iii) the material must be corrosion resistant.…”

Section: Alloys Ofmentioning

confidence: 99%

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Hybrid functional investigations of band gaps and band alignments for AlN, GaN, InN, and InGaN

Moses

Miao

Yan

et al. 2011

The Journal of Chemical Physics

284

231

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Band gaps and band alignments for AlN, GaN, InN, and InGaN alloys are investigated using density functional theory with the with the Heyd-Scuseria-Ernzerhof {HSE06 [J. Heyd, G. E. Scuseria, and M. Ernzerhof, J. Chem. Phys. 134, 8207 (2003); 124, 219906 (2006)]} XC functional. The band gap of InGaN alloys as a function of In content is calculated and a strong bowing at low In content is found, described by bowing parameters 2.29 eV at 6.25% and 1.79 eV at 12.5%, indicating the band gap cannot be described by a single composition-independent bowing parameter. Valence-band maxima (VBM) and conduction-band minima (CBM) are aligned by combining bulk calculations with surface calculations for nonpolar surfaces. The influence of surface termination [(1100) mplane or (1120) a-plane] is thoroughly investigated. We find that for the relaxed surfaces of the binary nitrides the difference in electron affinities between m-and a-plane is less than 0.1 eV. The absolute electron affinities are found to strongly depend on the choice of XC functional. However, we find that relative alignments are less sensitive to the choice of XC functional. In particular, we find that relative alignments may be calculated based on Perdew-Becke-Ernzerhof [J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Lett. 134, 3865 (1996)] surface calculations with the HSE06 lattice parameters. For InGaN we find that the VBM is a linear function of In content and that the majority of the band-gap bowing is located in the CBM. Based on the calculated electron affinities we predict that InGaN will be suited for water splitting up to 50% In content.

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Section: Alloys Ofmentioning

confidence: 99%

“…InGaN alloys have been found to fulfill these criteria and are, therefore, a potential candidate as a photoelectrode. [13][14][15][16][17][18][19][20] In the present study we focus on criteria (i) and (ii) and the materials properties of interest are, therefore, the band gap and band alignments.…”

Section: Alloys Ofmentioning

confidence: 99%

Hybrid functional investigations of band gaps and band alignments for AlN, GaN, InN, and InGaN

Moses

Miao

Yan

et al. 2011

The Journal of Chemical Physics

284

231

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“…Experimentally, single crystalline In x Ga 1-x N nanowires with compositions up to x = 0.4~0.5 have been realized. 16 Although the InGaN alloy is a very promising water splitting material, only a few studies have been reported [17][18][19] with no studies on nanowire geometries.One dimensional nanostructures have been demonstrated to be efficient in photoelectrochemical (PEC) cell and photovoltaic cell applications because they can decouple the directions of light absorption and charge carrier collection. [20][21] When the life time of the minority carrier is short, the minority carrier can recombine in bulk before it reaches the semiconductor/electrolyte junction.…”

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confidence: 99%

Si/InGaN Core/Shell Hierarchical Nanowire Arrays and their Photoelectrochemical Properties

et al. 2012

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Three dimensional hierarchical nanostructures were synthesized by the halide chemical vapor deposition (HCVD) of InGaN nanowires on Si wire arrays. Single phase InGaN nanowires grew vertically on the sidewalls of Si wires and acted as a high surface area photoanode for solar water splitting. Electrochemical measurements showed that the photocurrent density with hierarchical Si/InGaN nanowire arrays increased by 5 times compared to the photocurrent density with InGaN nanowire arrays grown on planar Si (1.23 V vs RHE). High resolution transmission electron microscopy showed that InGaN nanowires are stable after 15 hours of illumination. These measurements show that Si/InGaN hierarchical nanostructures are a viable high surface area geometry for stable solar water splitting. KEYWORDS:Hierarchical nanostructure, InGaN nanowire, Si wire, photoanode, solar water splitting IntroductionPhotolysis of water with semiconductor materials has been investigated as a clean and renewable energy conversion process by storing solar energy in chemical bonds such as hydrogen. [1][2][3] Since Fujishima and Honda 4 reported the capability of water splitting with TiO 2 , metal oxide semiconductors have been studied extensively due to their stability under photo-anodic conditions. [5][6] However, the valence band of metal oxide semiconductors consists mainly of O 2p orbitals resulting in a low energy maximum (around +3 V vs NHE compared to +1.23 V vs NHE for the water oxidation reaction). This leads to a significant loss in energy from the large difference in potential between the valence band and water oxidation reaction. In addition, lowering the metal oxide bandgap energy for visible light absorption generally comes at the cost of moving the conduction band minimum (CBM) towards lower potentials than the hydrogen reduction potential which cannot perform spontaneous solar water splitting.On the other hand, metal nitrides have less positive valence band maximum (VBM) potentials than metal oxides because N 2p orbitals have smaller ionization energies than O 2p orbitals. [6][7] For example, GaN is one of the nitride semiconductors that have been studied for photocatalytic applications [8][9][10][11] because its CBM and VBM straddle the hydrogen reduction (H + /H 2 ) and water oxidation (H 2 O/O 2 ) potentials. Although GaN has a large bandgap (3.4 eV), indium alloying to form InGaN can tune the bandgap from the ultraviolet to the near infrared region 12 encompassing the entire solar spectrum. The In 0.5 Ga 0.5 N alloy has a bandgap of around 2.0 eV which is desirable for overall water splitting considering the overpotential for the water oxidation reaction. [13][14] Moses et al. 15 calculated that the VBM of InGaN alloy increases in energy almost linearly with indium composition. Therefore, the InGaN alloy was suggested to accomplish spontaneous overall water splitting with up to 50% indium incorporation since both the CBM and VBM can satisfy the energetic requirements. Experimentally, single crystalline In x Ga 1-x N nanowire...

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“…Being strongly 11,12 properties of the semiconductor surface are closely related and dependent on the indium content, the CB edge lies below influence the performance of the whole device. The role of the surface states on the charge transfer across the semiconductor− liquid interface (SLI) is of great importance, especially on how they can severely limit the photocarrier extraction, leading to an undesired overpotential.…”

Section: Introductionmentioning

confidence: 99%

Charge Transfer Characteristics of n-type In_0.1Ga_0.9N Photoanode across Semiconductor–Liquid Interface

et al. 2016

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Understanding the mechanisms of charge transfer across the semiconductor/liquid interface is crucial to realize efficient photoelectrochemical devices. Here, the interfacial charge transfer characteristics of n-type In 0.1 Ga 0.9 N photoanodes are investigated and correlated to their photo-activity properties measured in phosphate buffered saline solution (pH 7) under illumination conditions. Cyclic voltammetry measurements show evident photoactivity changes as the number of cycles increases. In particular, the photocurrent density reaches its maximum value after 49 voltammetric cycles; meanwhile, the photocurrent onset potential shifts toward more negative cathodic potentials. Electrochemical impedance measurements reveal that, first, the hole transfer process occurs mainly via localized states at the surface and the photocurrent onset potential is dependent on the energetic position of those states. Therefore, the observed initial photocurrent increase and cathodic shift of the photocurrent onset potential can be attributed to a decrease of the transfer resistance and partial passivation of the states at the surface. On the other hand, a gradual oxidation and corrosion of the InGaN surface arises, causing a consequential decrease of the photocurrent. At this point, the charge transfer process occurs predominantly from the valence band. This work provides a basic understanding of the charge transfer mechanisms across the InGaN/liquid interface which can be used to improve the overall photoanode efficiency.

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Photoelectrochemical Properties of InGaN for H₂ Generation from Aqueous Water

Cited by 85 publications

References 11 publications

Hybrid functional investigations of band gaps and band alignments for AlN, GaN, InN, and InGaN

Hybrid functional investigations of band gaps and band alignments for AlN, GaN, InN, and InGaN

Si/InGaN Core/Shell Hierarchical Nanowire Arrays and their Photoelectrochemical Properties

Charge Transfer Characteristics of n-type In_0.1Ga_0.9N Photoanode across Semiconductor–Liquid Interface

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Photoelectrochemical Properties of InGaN for H2 Generation from Aqueous Water

Cited by 85 publications

References 11 publications

Hybrid functional investigations of band gaps and band alignments for AlN, GaN, InN, and InGaN

Hybrid functional investigations of band gaps and band alignments for AlN, GaN, InN, and InGaN

Si/InGaN Core/Shell Hierarchical Nanowire Arrays and their Photoelectrochemical Properties

Charge Transfer Characteristics of n-type In0.1Ga0.9N Photoanode across Semiconductor–Liquid Interface

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Product

Resources

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Photoelectrochemical Properties of InGaN for H₂ Generation from Aqueous Water

Charge Transfer Characteristics of n-type In_0.1Ga_0.9N Photoanode across Semiconductor–Liquid Interface