Investigations of the electrochemical stability of InGaN photoanodes in different electrolytes

Finken, Matthias; Wille, Ada; Reuters, B.; Heuken, M.; Kalisch, H.; Vescan, A.

doi:10.1002/pssb.201451576

Cited by 8 publications

(7 citation statements)

References 14 publications

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“…In the present study we aim at investigating charge carrier generation and separation in (In,Ga)N NWs with higher In content, and thus we employ n -type material. Since its photocorrosion would hinder the assessment of the photoanode performance, , we study first the impact of adding H 2 O 2 as a hole scavenger on the stability of the electrode. The oxidation of H 2 O 2 is described by the following equation: Since this reaction is much faster than water oxidation, one expects photogenerated holes to be effectively consumed for the oxidation of H 2 O 2 so that they are no longer available for corrosion processes.…”

Section: Resultsmentioning

confidence: 99%

Section: Gan Gmentioning

confidence: 99%

“…To investigate the influence of the charge carrier generation and separation on the photocurrent of (In,Ga)N NWs as a possible photoanode for water oxidation, we use H 2 O 2 as a hole scavenger. , The fast oxidation kinetics of H 2 O 2 prevents a limitation of the photocurrent by the electrochemical reaction so that only the influence of electronic effects within the (In,Ga)N NWs becomes visible. Furthermore, by addition of H 2 O 2 the anodic photocorrosion is suppressed, which is normally a limiting factor for n -type GaN and (In,Ga)N. ,− For NWs with an In content of 16% we find photocurrents that are very close to the theoretical maximum expected for the corresponding band gap.…”

Section: Introductionmentioning

confidence: 99%

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Broad Band Light Absorption and High Photocurrent of (In,Ga)N Nanowire Photoanodes Resulting from a Radial Stark Effect

Kamimura

Bogdanoff

Corfdir

et al. 2016

ACS Appl. Mater. Interfaces

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The photoelectrochemical properties of (In,Ga)N nanowire photoanodes are investigated using HO as a hole scavenger to prevent photocorrosion. Under simulated solar illumination, InGaN nanowires grown by plasma-assisted molecular beam epitaxy show a high photocurrent of 2.7 mA/cm at 1.2 V vs reversible hydrogen electrode. This value is almost the theoretical maximum expected from the corresponding band gap (2.8 eV) for homogeneous bulk material without taking into account surface effects. These nanowires exhibit a higher incident photon-to-current conversion efficiency over a broader wavelength range and a higher photocurrent than a compact layer with higher In content of 28%. These results are explained by the combination of built-in electric fields at the nanowire sidewall surfaces and compositional fluctuations in (In,Ga)N, which gives rise to a radial Stark effect. This effect enables spatially indirect transitions at energies much lower than the band gap. The resulting broad band light absorption leads to high photocurrents. This benefit of the radial Stark effect in (In,Ga)N nanowires for solar harvesting applications opens up the perspective to break the theoretical limit for photocurrents.

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Section: Resultsmentioning

confidence: 99%

Section: Gan Gmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Broad Band Light Absorption and High Photocurrent of (In,Ga)N Nanowire Photoanodes Resulting from a Radial Stark Effect

Kamimura

Bogdanoff

Corfdir

et al. 2016

ACS Appl. Mater. Interfaces

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“…[ 10 ] However, in the case of n‐type In x Ga 1– x N photoanodes, photocorrosion has been observed. [ 11–15 ] At the same time, p‐type In x Ga 1– x N alloys are known as stable photocathodes, but there are difficulties in growth because these alloys are due to unintentional doping normally n‐type. [ 15,16 ]…”

Section: Figurementioning

confidence: 99%

Protection Mechanism against Photocorrosion of GaN Photoanodes Provided by NiO Thin Layers

et al. 2020

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The photoelectrochemical properties of n‐type Ga‐polar GaN photoelectrodes covered with NiO layers of different thicknesses in the range 0–20 nm are investigated for aqueous solution. To obtain layers of well‐defined thickness and high crystal quality, NiO is grown by plasma‐assisted molecular‐beam epitaxy. Stability tests reveal that the NiO layers suppress photocorrosion. With increasing NiO thickness, the onset of the photocurrent is shifted to more positive voltages and the photocurrent is reduced, especially for low bias potentials, indicating that hole transfer to the electrolyte interface is hindered by thicker NiO layers. Furthermore, cathodic transient spikes are observed under intermittent illumination, which hints at surface recombination processes. These results are inconsistent with the common explanation of the protection mechanism that the band alignment of GaN/NiO enables efficient hole‐injection, thus preventing hole accumulation at the GaN surface that would lead to anodic photocorrosion. Interestingly, the morphology of the etch pits as well as further experiments involving the photodeposition of Ag indicate that photocorrosion of GaN photoanodes is related to reductive processes at threading dislocations. Therefore, it is concluded that the NiO layers block the transfer of photogenerated electrons from GaN to the electrolyte interface, which prevents the cathodic photocorrosion.

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“…One Higher stability of n-type InGaN towards etching (photo-corrosion) is expected when used with co-catalysts and HBr shows most stable results [Finken 2015] [Luo 2008].…”

Section: Water Splitting (Hydrogen Generation)mentioning

confidence: 99%

Investigations on III-Nitrides nanostructures: application to Renewable Energies and Bio-Sensing

Rodriguez¹,

David²

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Investigations of the electrochemical stability of InGaN photoanodes in different electrolytes

Cited by 8 publications

References 14 publications

Broad Band Light Absorption and High Photocurrent of (In,Ga)N Nanowire Photoanodes Resulting from a Radial Stark Effect

Broad Band Light Absorption and High Photocurrent of (In,Ga)N Nanowire Photoanodes Resulting from a Radial Stark Effect

Protection Mechanism against Photocorrosion of GaN Photoanodes Provided by NiO Thin Layers

Investigations on III-Nitrides nanostructures: application to Renewable Energies and Bio-Sensing

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