Efficient solar hydrogen production from neutral electrolytes using surface-modified Cu(In,Ga)Se<sub>2</sub>photocathodes

Kumagai, Hiromu; Minegishi, Tsutomu; Sato, Nagaaki; Yamada, Taro; Kubota, Jun; Domen, Kazunari

doi:10.1039/c5ta01058f

Cited by 160 publications

(150 citation statements)

References 48 publications

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“…It should be noted that the Pt/CdS/CuGa3Se5/AgxCu1−xGaSe2 photocathode produced hydrogen stably for over 19 days. A large leap in maximum photocurrent and HC-STH was achieved using a surface-modified CIGS-based photocathode with thin conductor layers employing a neutral phosphate buffer solution as an electrolyte [47]. This suggested that a conductor layer such as titanium and molybdenum prevents the formation of a Schottky barrier between Pt and CdS.…”

Section: Hydrogen Evolution From Water Using Copper Chalcopyrite Photmentioning

confidence: 99%

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

2015

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Abstract:Copper chalcopyrite is a promising candidate for a photocathode material for photoelectrochemical (PEC) water splitting because of its high half-cell solar-to-hydrogen conversion efficiency (HC-STH), relatively simple and low-cost preparation process, and chemical stability. This paper reviews recent advances in copper chalcopyrite photocathodes. The PEC properties of copper chalcopyrite photocathodes have improved fairly rapidly: HC-STH values of 0.25% and 8.5% in 2012 and 2015, respectively. On the other hand, the onset potential remains insufficient, owing to the shallow valence band maximum mainly consisting of Cu 3d orbitals. In order to improve the onset potential, we explored substituting Cu for Ag and investigate the PEC properties of silver gallium selenide (AGSe) thin film photocathodes for varying compositions, film growth atmospheres, and surfaces. The modified AGSe photocathodes showed a higher onset potential than copper chalcopyrite photocathodes. It was demonstrated that element substitution of copper chalcopyrite can help to achieve more efficient PEC water splitting.

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Section: Hydrogen Evolution From Water Using Copper Chalcopyrite Photmentioning

confidence: 99%

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

2015

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“…Kumagai et al suggested that the Ti and Mo layers suppress Schottky barrier formation at the Pt/CdS interface, and enhance electron flow to the Pt. [19] The Ti layer forms an intimate contact with the CdS with a lower potential [8] and ZnSe. The VBM for ZnSe is obtained from PESA measurements (see Figure 2), and the bandgap is set to 2.7 eV.…”

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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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109

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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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“…Indeed, a CIGSe/CdS/Pt photocathode generating an outstanding photocurrent density of ca. 25 mA cm −2 at applied potential of 0V versus RHE and a V OC of +0.65 V versus RHE under standard 1 Sun illumination and in a neutral pH electrolyte was reported [29]. Stronger driving force thanks to very negative conduction band edge potential of ca.…”

Section: Chalcopyrite-type Semiconductorsmentioning

confidence: 93%

“…8.0 mA cm −2 was achieved for a Cu 2 O photocathode [27,30] while that of ca. 25 mA cm −2 was recorded for a CIGS photocathode [29]. We note that even fill-factor (ff) is a critical parameter to appreciate the actually performance of a photoelectrochemical device, e.g.…”

Section: Current Achievements and Remained Technicalmentioning

confidence: 99%

Current perspectives in engineering of viable hybrid photocathodes for solar hydrogen generation

Thuy

et al. 2018

Adv. Nat. Sci: Nanosci. Nanotechnol.

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Photoelectrochemical water splitting represents an attractive technological solution to harvest and then store the solar energy which is abundant but intermittent. It can be achieved by employing a photoelectrochemical cell, also called an artificial leaf. In order to construct viable photoeclectrochemical cells, efforts are being dedicated to engineer robust and efficient photocathodes for solar H 2 generation and photoanodes for solar water oxidation reaction. In this article, we discuss on the recent achievements and current perspectives in engineering of viable hybrid photocathodes. The state of the art on the design of a hybrid photocathode, its performance as well as the current understanding of its mechanistic operation will be first described. We then discuss on the technical strategies that are currently being developed to enhance the robustness and performance of a hybrid photocathode.

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Efficient solar hydrogen production from neutral electrolytes using surface-modified Cu(In,Ga)Se₂photocathodes

Cited by 160 publications

References 48 publications

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

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

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

Current perspectives in engineering of viable hybrid photocathodes for solar hydrogen generation

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Efficient solar hydrogen production from neutral electrolytes using surface-modified Cu(In,Ga)Se2photocathodes

Cited by 160 publications

References 48 publications

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

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

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

Current perspectives in engineering of viable hybrid photocathodes for solar hydrogen generation

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Efficient solar hydrogen production from neutral electrolytes using surface-modified Cu(In,Ga)Se₂photocathodes

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