Photo-Electrochemical Behaviors of Semiconductor Electrodes Coated With Thin Metal Films

Nakato, Yoshihiro; Ohnishi, T.; Tsubomura, Hiroshi

doi:10.1246/cl.1975.883

Cited by 104 publications

(81 citation statements)

References 7 publications

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“…4 Protective coatings have been investigated in detail, but with only secondary emphasis on operation in highly alkaline (pH 14) media. Thin metal films have been used for this purpose [24][25][26], although work has mostly focused on the behavior of photoanodes in buffered media at near-neutral pH. A thin layer of Ni has been shown to provide substantial stability for Si photoanodes in alkaline media [26].…”

Section: Introductionmentioning

confidence: 99%

Protection of inorganic semiconductors for sustained, efficient photoelectrochemical water oxidation

Lichterman

Sun

et al. 2016

Catalysis Today

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Small-band-gap (E g < 2 eV) semiconductors must be stabilized for use in integrated devices that convert solar energy into the bonding energy of a reduced fuel, specifically H 2 (g) or a reduced-carbon species such as CH 3 OH or CH 4 . To sustainably and scalably complete the fuel cycle, electrons must be liberated through the oxidation of water to O 2 (g). Strongly acidic or strongly alkaline electrolytes are needed to enable efficient and intrinsically safe operation of a full solar-driven water-splitting system. However, under water-oxidation conditions, the smallband-gap semiconductors required for efficient cell operation are unstable, either dissolving or forming insulating surface oxides. We describe herein recent progress in the protection of semiconductor photoanodes under such operational conditions. We specifically describe the properties of two protective overlayers, TiO 2 /Ni and NiO x , both of which have demonstrated the ability to protect otherwise unstable semiconductors for >100 h of continuous solar-driven water oxidation when in contact with a highly alkaline aqueous electrolyte (1.0 M KOH(aq)). The 2 stabilization of various semiconductor photoanodes is reviewed in the context of the electronic characteristics and a mechanistic analysis of the TiO 2 films, along with a discussion of the optical, catalytic, and electronic nature of NiO x films for stabilization of semiconductor photoanodes for water oxidation.

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Section: Introductionmentioning

confidence: 99%

Protection of inorganic semiconductors for sustained, efficient photoelectrochemical water oxidation

Lichterman

Sun

et al. 2016

Catalysis Today

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“…A number of methods to prevent its surface passivation have been reported. In general, the protection takes place by deposition of metal islands or thin metallic coatings [5][6][7][8]. In addition, these processes can also improve the low catalytic properties of the Si surface.…”

Section: Introductionmentioning

confidence: 99%

“…When metallic deposits are small, creating sparsely scattered islands, a very high photovoltage is generated [7]. But when the semiconductor is uniformly covered with a metallic layer the photovoltage decreases drastically, or may even totally disappear [8]. The Si surface has also been stabilized against oxidation by surface chemical functionalization to be used as a photoanode in contact with aqueous environments.…”

Section: Introductionmentioning

confidence: 99%

Photoelectrochemical characterization of p-type silicon electrodes covered with tunnelling nitride dielectric films

Lana–Villarreal¹,

Straboni²,

Pichon³

et al. 2007

Thin Solid Films

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“…Moreover, the conduction band edge of n-TiO 2 is too low 25 for photoexcited electrons in the conduction band to reduce water effectively into hydrogen with no external bias. On the other hand, Si efficiently absorbs solar light, but is unstable in aqueous electrolytes 26,27 . Many studies have been made to stabilize unstable Si.…”

Section: Introductionmentioning

confidence: 99%

Solar water splitting with a composite silicon/metal oxide semiconductor electrode

et al. 2006

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We have studied solar water splitting with a composite semiconductor electrode, composed of an n-i-p junction amorphous silicon (a-Si, E g 1.7 eV) layer, an indium tin oxide (ITO) layer, and a tungsten trioxide (WO 3 , E g 2.8 eV) particulate layer. The n-i-p a-Si layer, which had more accurately a structure of n-type microcrystalline ( c) 3C-SiC:H (25 nm)/i-type a-Si:H (400 nm)/p-type a-SiC x :H (25 nm), was prepared on a TiO 2 -covered F-doped SnO 2 (FTO)/glass plate by a Hot-Wire CVD method. The ITO layer (100 nm thick) was deposited on the p-type a-Si by the DC magnetron sputtering method, and the WO 3 particulate layer was formed by a doctor-blade method, using a colloidal solution of commercial WO 3 powder of 10-30 nm in diameter. The composite electrode thus prepared was finally heat-treated at 300 C for 1 h. The anodic (water oxidation) photocurrent for the composite electrode in 0.1 M Na 2 SO 4 yielded an IPCE (incident photon to current efficiency) of about 6 % at 400 nm and was stable for more than 24 h. Besides, the onset potential lay a little (by about 0.05 V) more negative than the equilibrium hydrogen evolution potential, indicating a possibility of solar water splitting with no external bias. A preliminary result for the water photooxidation with an "nGaP/p-Si/Pt dot" electrode is also reported briefly.

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Photo-Electrochemical Behaviors of Semiconductor Electrodes Coated With Thin Metal Films

Abstract: Contrary to most ordinary semiconductor electrodes, metal-coated semiconductor electrodes have been found to cause photocurrents in aqueous solutions without dissolution into or reaction with the solution, and will be useful as solar-energy convertors.

Cited by 104 publications

References 7 publications

Protection of inorganic semiconductors for sustained, efficient photoelectrochemical water oxidation

Protection of inorganic semiconductors for sustained, efficient photoelectrochemical water oxidation

Photoelectrochemical characterization of p-type silicon electrodes covered with tunnelling nitride dielectric films

Solar water splitting with a composite silicon/metal oxide semiconductor electrode

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