Chalcopyrite Thin Film Materials for Photoelectrochemical Hydrogen Evolution from Water under Sunlight

Kaneko, Hiroyuki; Minegishi, Tsutomu; Domen, Kazunari

doi:10.3390/coatings5030293

Cited by 21 publications

(16 citation statements)

References 65 publications

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“…Altogether, these surface treatments are known to effi ciently shift the onset of photocurrent and increase the overall solar to hydrogen effi ciency. [ 4 ] In search of an all-solution-processable chalcogenide-based photocathode, the deposition of TiO 2 has been a major limitation since it is commonly deposited by sputtering [ 15 ] or atomic layer deposition. [ 13 ] In this study we use a straightforward solgel technique to deposit a TiO 2 overlayer.…”

Section: Overlayersmentioning

confidence: 99%

“…The I-III-VI 2 chalcopyrite p-type semiconductors (I = Cu, Ag; III = Ga, In; VI = S, Se) have recently emerged as promising materials for application as photocathodes for the tandem cell, [ 4,5 ] given their success in the PV fi eld. [ 6,7 ] The attractiveness of these materials lies in their high extinction coeffi cients, large minority-carrier diffusion lengths (few micrometers), easily tunable band-gap energy (1.0-2.4 eV) by adjusting the alloy composition, and well-positioned conduction band for water photoreduction.…”

Section: Introductionmentioning

confidence: 99%

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A Bottom‐Up Approach toward All‐Solution‐Processed High‐Efficiency Cu(In,Ga)S₂ Photocathodes for Solar Water Splitting

Guijarro

Prévot

et al. 2016

Advanced Energy Materials

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The development of solution‐processable routes to prepare efficient photoelectrodes for water splitting is highly desirable to reduce manufacturing costs. Recently, sulfide chalcopyrites (Cu(In,Ga)S2) have attracted attention as photocathodes for hydrogen evolution owing to their outstanding optoelectronic properties and their band gap—wider than their selenide counterparts—which can potentially increase the attainable photovoltage. A straightforward and all‐solution‐processable approach for the fabrication of highly efficient photocathodes based on Cu(In,Ga)S2 is reported for the first time. It is demonstrated that semiconductor nanocrystals can be successfully employed as building blocks to prepare phase‐pure microcrystalline thin films by incorporating different additives (Sb, Bi, Mg) that promote the coalescence of the nanocrystals during annealing. Importantly, the grain size is directly correlated to improved charge transport for Sb and Bi additives, but it is shown that secondary effects can be detrimental to performance even with large grains (for Mg). For optimized electrodes, the sequential deposition of thin layers of n‐type CdS and TiO2 by solution‐based methods, and platinum as an electrocatalyst, leads to stable photocurrents saturating at 8.0 mA cm–2 and onsetting at ≈0.6 V versus RHE under AM 1.5G illumination for CuInS2 films. Electrodes prepared by our method rival the state‐of‐the‐art performance for these materials.

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Section: Overlayersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Bottom‐Up Approach toward All‐Solution‐Processed High‐Efficiency Cu(In,Ga)S₂ Photocathodes for Solar Water Splitting

Guijarro

Prévot

et al. 2016

Advanced Energy Materials

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“…[21][22][23] As shown in Scheme 1, for a solid solution of ZnSe and CIGS, the VBM is expected to be deeper than that for CIGS, and the absorption edge longer than that for ZnSe. In this work, we investigated the PEC properties of (ZnSe) x (CIGS) 1-x thin-film photocathodes.…”

mentioning

confidence: 99%

A Novel Photocathode Material for Sunlight‐Driven Overall Water Splitting: Solid Solution of ZnSe and Cu(In,Ga)Se₂

Kaneko

Minegishi

Nakabayashi

et al. 2016

Adv Funct Materials

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108

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content; a similar effect has been found for other material systems. [21][22][23] As shown in Scheme 1, for a solid solution of ZnSe and CIGS, the VBM is expected to be deeper than that for CIGS, and the absorption edge longer than that for ZnSe. In this work, we investigated the PEC properties of (ZnSe) x (CIGS) 1-x thin-film photocathodes. The VBM was 0.25 V deeper than that for CIGS, and the onset potential was 0.89 V RHE , which is 0.17 V higher than that for CIGS. This higher onset potential allows PEC cells to be fabricated with a variety of photoanodes without the need for an external bias voltage. [24][25][26][27] Moreover, (ZnSe) 0.85 (CIGS) 0.15 contains much less of the rare metals indium and gallium. Therefore, (ZnSe) 0.85 (CIGS) 0.15 offers advantages over CIGS from the viewpoint of large-scale applications.Using a (ZnSe) 0.85 (CIGS) 0.15 photocathode with a BiVO 4 photoanode, [28] PEC overall water splitting without the need for an external bias voltage was demonstrated. The two-electrode cell produced stoichiometric amounts of H 2 and O 2 under simulated sunlight. The maximum STH was 0.91%, which is one of the highest values reported for a PEC cell containing a photoanode and a photocathode. [4] Results and Discussion PEC Properties of (ZnSe) 0.85 (CIGS) 0.15 PhotocathodesCurrent density versus potential curves for Pt and Pt/CdS modified (ZnSe) 0.85 (CIGS) 0.15 photocathodes are shown in Figure 1a. This composition was found to produce the largest photocurrent at 0.5 V RHE , as discussed in the next section.Whereas the photocathode modified by Pt alone showed a small cathodic photoresponse, the photocathode modified with both Pt and CdS exhibited a large photocurrent density of 6.5 mA cm −2 at 0 V RHE with a relatively high onset potential of 0.81 V RHE , which was defined as a cathodic photocurrent density of 0.05 mA cm −2 . It has been reported that an n-type CdS layer enhances the degree of charge separation by forming a p-n junction at the solid-liquid interface with the underlying p-type layer, which leads to a larger photocurrent and a higher onset potential because of the change in the band alignment. [29,30] As shown in Figure S1 (Supporting Information), the Pt/CdS/(ZnSe) 0.85 (CIGS) 0.15 photocathode showed no decay in the photocurrent at 0.1 V RHE over a period of more than 1 h. Such stable hydrogen evolution from water is similar to that reported for photocathodes based on chalcopyrites. [30][31][32] The incident photon to current conversion efficiency (IPCE) spectrum shown in Figure 1b indicates that the absorption edge is located around 900 nm. Despite the relatively high fraction of ZnSe, whose absorption edge is about 460 nm, the absorption edge for (ZnSe) 0.85 (CIGS) 0.15 is close to that for CIGS (≈1100 nm). Thus, due to its bandgap and onset potential, (ZnSe) 0.85 (CIGS) 0.15 is the promising material for sunlightdriven hydrogen production from water.Furthermore, insertion of 3-nm-thick Mo and Ti layers between the Pt and CdS improves the photocurrent around the onset potentia...

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“…Materials other than oxides have attracted much attention due to their long absorption edge wavelengths, which enable the utilization of a large portion of the natural sunlight spectrum. In particular, polycrystalline copper chalcopyrite‐based photocathodes have been reported to generate relatively high photocurrent values and to exhibit good stability during hydrogen evolution . It has also been determined that chemical bath deposition of CdS and/or In 2 S 3 onto the photocathode surface enhances the separation of photoexcited electrons and holes at the electrode–electrolyte interface .…”

Section: Introductionmentioning

confidence: 99%

“…In particular, polycrystalline copper chalcopyrite-based photocathodes have been reported to generate relatively high photocurrent values and to exhibit good stability during hydrogen evolution. [6,7] It has also been determined that chemical bath deposition of CdS and/or In 2 S 3 onto the photocathode surface enhances the separation of photoexcited electrons and holes at the electrode-electrolyte interface. [8,9] Moreover, additional modification with a metal conductor layer on top of the sulfide layer facilitates electron transfer from the sulfide layer to the reaction sites.…”

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confidence: 99%

Stable Hydrogen Production from Water on an NIR‐Responsive Photocathode under Harsh Conditions

et al. 2018

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Photoelectrochemical (PEC) water splitting using a cell composed of a photocathode and photoanode is an attractive approach to producing hydrogen utilizing solar energy. Photocathodes based on nonoxide materials exhibit high solar‐to‐hydrogen conversion efficiencies thanks to their narrow bandgaps. However, the corrosion of photocathode surfaces at oxidative potentials and under highly alkaline conditions has resulted in insufficient durability. Here, the PEC properties of near‐infrared‐sensitive (ZnSe)0.85(CuIn0.7Ga0.3Se2)0.15‐based photocathodes coated with a RuO2 nanolayer using a photo‐electrodeposition method are investigated under harsh conditions. A RuO2‐coated (ZnSe)0.85(CuIn0.7Ga0.3Se2)0.15 photocathode exhibits no degradation during the PEC hydrogen evolution reaction (HER) at 0.6 VRHE for longer than 10 h in electrolytes having pH values of 7 or 13. Maximum photocurrents of 9.1 and 2.9 mA cm−2 are obtained at 0 and 0.6 VRHE, respectively, under simulated sunlight without the use of any other HER catalyst or a conductor layer. This study therefore demonstrates a useful method for the fabrication of efficient, durable PEC cells using nonoxide photocathodes.

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Chalcopyrite Thin Film Materials for Photoelectrochemical Hydrogen Evolution from Water under Sunlight

Cited by 21 publications

References 65 publications

A Bottom‐Up Approach toward All‐Solution‐Processed High‐Efficiency Cu(In,Ga)S₂ Photocathodes for Solar Water Splitting

A Bottom‐Up Approach toward All‐Solution‐Processed High‐Efficiency Cu(In,Ga)S₂ Photocathodes for Solar Water Splitting

A Novel Photocathode Material for Sunlight‐Driven Overall Water Splitting: Solid Solution of ZnSe and Cu(In,Ga)Se₂

Stable Hydrogen Production from Water on an NIR‐Responsive Photocathode under Harsh Conditions

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Chalcopyrite Thin Film Materials for Photoelectrochemical Hydrogen Evolution from Water under Sunlight

Cited by 21 publications

References 65 publications

A Bottom‐Up Approach toward All‐Solution‐Processed High‐Efficiency Cu(In,Ga)S2 Photocathodes for Solar Water Splitting

A Bottom‐Up Approach toward All‐Solution‐Processed High‐Efficiency Cu(In,Ga)S2 Photocathodes for Solar Water Splitting

A Novel Photocathode Material for Sunlight‐Driven Overall Water Splitting: Solid Solution of ZnSe and Cu(In,Ga)Se2

Stable Hydrogen Production from Water on an NIR‐Responsive Photocathode under Harsh Conditions

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A Bottom‐Up Approach toward All‐Solution‐Processed High‐Efficiency Cu(In,Ga)S₂ Photocathodes for Solar Water Splitting

A Bottom‐Up Approach toward All‐Solution‐Processed High‐Efficiency Cu(In,Ga)S₂ Photocathodes for Solar Water Splitting

A Novel Photocathode Material for Sunlight‐Driven Overall Water Splitting: Solid Solution of ZnSe and Cu(In,Ga)Se₂