Hydrogen Gas Generation by Splitting Aqueous Water Using n-Type GaN Photoelectrode with Anodic Oxidation

Fujii, K.; Karasawa, T.; Ohkawa, Kazuhiro

doi:10.1143/jjap.44.l543

Cited by 150 publications

(147 citation statements)

References 8 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

281

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

281

231

View full text Add to dashboard Cite

show abstract

“…[6][7][8] In addition, the bandgap energy of GaN-based materials can be varied from about 0.65 to 6.0 eV by alloying them with InN and AlN, which enables us to design various functional photoelectrodes not only for spectral matching of solar light but also for the electrochemical reduction of CO 2 to carbohydrate. 9 One of the common approaches to improving conversion efficiency is to form nanostructures on the photoelectrode surface in order to increase its surface area.…”

mentioning

confidence: 99%

Correlation between Structural and Photoelectrochemical Properties of GaN Porous Nanostructures Formed by Photo-Assisted Electrochemical Etching

Kumazaki¹,

Watanabe²,

Yatabe³

et al. 2014

J. Electrochem. Soc.

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We investigated the correlation between structural and photoelectrochemical properties of GaN porous nanostructures formed by photo-assisted electrochemical etching. The porous nanostructures were formed during light irradiation of the top-surface of homo-epitaxial layers grown on freestanding GaN substrates. The pore depth, wall thickness, and surface morphology of porous nanostructures were strongly influenced by the way holes generated by the light irradiation were supplied. Such structural features influenced the optical properties of GaN porous nanostructures. The photoluminescence peaks measured on GaN porous nanostructures were shifted to higher energies because of the quantum confinement in the thin GaN walls between pores. Formation of porous nanostructure decreased the photoreflectance of the GaN surface, and the smallest reflectance was obtained from the porous sample having large pores on its surface after the ultrathin layer with small pores had been removed by surface-etching. The photoelectrochemical response measured on GaN porous nanostructures in a NaCl electrolyte were drastically enhanced by the unique features of those structures, such as low photoreflectance and large surface area. The largest photocurrents were obtained from the sample from which H 3 PO 4 treatment had removed the ultrathin layer without thinning the pore walls. Photoelectrochemical systems based on semiconductor photoelectrodes have recently attracted much attention due to their potential use in the next generation of green technologies such as water splitting for fuel cells, artificial photosynthesis, and so on.1-5 Among the photoelectrode materials, GaN is one of the most attractive because of its chemical stability and its potential to achieve direct photoelectrolysis by solar power without the consumption of electric power. [6][7][8] In addition, the bandgap energy of GaN-based materials can be varied from about 0.65 to 6.0 eV by alloying them with InN and AlN, which enables us to design various functional photoelectrodes not only for spectral matching of solar light but also for the electrochemical reduction of CO 2 to carbohydrate. 9 One of the common approaches to improving conversion efficiency is to form nanostructures on the photoelectrode surface in order to increase its surface area. Most reported GaN nanostructures have been made using selective-area growth 10,11 or a dry etching process such as reactive ion etching. 12,13 There are, however, severe limitations on increasing the density of nanostructures because most approaches use lithography for defining the size and position of the nanostructures. And when a dry etching process is involved, the etching damage induced by ion bombardment is not negligible [14][15][16] and could significantly degrade the photoelectrochemical efficiency.One alternative approach is an electrochemical-fabrication process, which can form various semiconductor nanostructures in a self-assembled fashion. The most well-known application of an electrochemical process is the formation...

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“…The semiconductor for solar water splitting should have the conduction and the valence band edge positions straddled H + /H 2 and O 2 /H 2 O redox potentials. GaN has a suitable band gap position for water splitting, but it activated only by ultraviolet light irradiation [6][7][8][9][10][11][12][13][14][15]. However the band gap of the solid solutions which was formatted with InN [16][17][18][19] and ZnO [20,21] can be controlled and solar water splitting under visible light irradiation can be achieved.…”

Section: Introductionmentioning

confidence: 99%

Photoelectrochemical Properties of GaN Synthesized by the Reaction of Ga with LiNH<sub>2</sub>

Zhang

Kouyama

Miura

et al. 2011

Trans. Mat. Res. Soc. Japan

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The photoelectrochemical properties of GaN particulate film electrode on Ti substrate were investigated. GaN particulate film electrode was fabricated by means of doctor blade technique. Two kinds of method were used to improve the connection between GaN particles. One is a heat treatment of GaN particulate thin film with LiNH 2 and another one is a heat treatment with TiCl 4 . From the results of the photoelectrochemical properties, GaN electrodes showed n-type semiconducting behavior in 1.0 M HCl electrolyte under UV irradiation. The high photocurrent response was achieved in the electrode with LiNH 2 treatment and TiCl 4 treatment because of its better connection of each GaN particle.

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Hydrogen Gas Generation by Splitting Aqueous Water Using n-Type GaN Photoelectrode with Anodic Oxidation

Cited by 150 publications

References 8 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

Correlation between Structural and Photoelectrochemical Properties of GaN Porous Nanostructures Formed by Photo-Assisted Electrochemical Etching

Photoelectrochemical Properties of GaN Synthesized by the Reaction of Ga with LiNH<sub>2</sub>

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