Improvement of hydrogen evolution under visible light over Zn1−2x(CuGa)xGa2S4photocatalysts by synthesis utilizing a polymerizable complex method

Quintans, Ciro Scheremeta; Kato, Hideki; Kobayashi, Makoto; Kaga, Hiroshi; Iwase, Akihide; Kudo, Akihiko; Kakihana, Masato

doi:10.1039/c5ta02114f

Cited by 12 publications

(5 citation statements)

References 51 publications

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“…The small variation of a VBM potential at lower x value than 0.5 is because of the relatively large bandgap bowing of (ZnSe) x (CIGS) 1-x material system. The results for both the lattice parameter and the VBM are similar to those reported for (ZnSe) x (CuInSe 2 ) 1-x by Li et al, and for (ZnS) x (CuGaS 2 ) 1-x by Quintans et al [36,37] It should be noted that the Mott-schottky plots revealed that the flat-band potential of (ZnSe) 0.89 (CIGS) 0.11 is about 0.2 V higher than that of CIGS indicating the about 0.2 V deeper VBM potential of (ZnSe) 0.89 (CIGS) 0.11 than that of CIGS. (see Figure S12 in the Supporting Information) The variation of the VBM potential between (ZnSe) 0.89 (CIGS) 0.11 and CIGS estimated by Mott-Schottky plots are consistent with PESA results.…”

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confidence: 88%

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

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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confidence: 88%

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

109

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“…CuGaS 2 has a direct band gap of 2.4 eV, which makes it less interesting for use in solar cells than CuInS 2 . However, since the wider band gap of CuGaS 2 is due to its CBM located at a more negative potential than that of CuInS 2 (Figure ), it can still serve as a photocathode for water reduction. − It may also be used for other solar fuel production reactions that require more negative potentials than hydrogen production.…”

Section: Electrochemical Synthesis Of Photocathodesmentioning

confidence: 99%

Electrochemical Synthesis of Photoelectrodes and Catalysts for Use in Solar Water Splitting

et al. 2015

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This review focuses on introducing and explaining electrodepostion mechanisms and electrodeposition-based synthesis strategies used for the production of catalysts and semiconductor electrodes for use in water-splitting photoelectrochemical cells (PECs). It is composed of three main sections: electrochemical synthesis of hydrogen evolution catalysts, oxygen evolution catalysts, and semiconductor electrodes. The semiconductor section is divided into two parts: photoanodes and photocathodes. Photoanodes include n-type semiconductor electrodes that can perform water oxidation to O2 using photogenerated holes, while photocathodes include p-type semiconductor electrodes that can reduce water to H2 using photoexcited electrons. For each material type, deposition mechanisms were reviewed first followed by a brief discussion on its properties relevant to electrochemical and photoelectrochemical water splitting. Electrodeposition or electrochemical synthesis is an ideal method to produce individual components and integrated systems for PECs due to its various intrinsic advantages. This review will serve as a good resource or guideline for researchers who are currently utilizing electrochemical synthesis as well as for those who are interested in beginning to employ electrochemical synthesis for the construction of more efficient PECs.

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“…For acquiring solar hydrogen, water splitting has been actively investigated using both photoelectrochemical and photocatalytic approaches. [1][2][3][4][5][6][7][8][9][10][11] Since the discovery of photoelectrochemical water splitting by Honda and Fujishima, 12 TiO 2 has been recognised as one of the most efficient photoanodes for the evolution of O 2 from water. Various types of structures with TiO 2 have been fabricated based on novel approaches.…”

mentioning

confidence: 99%

A water splitting system using an organo-photocathode and titanium dioxide photoanode capable of bias-free H₂ and O₂ evolution

et al. 2016

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This study examined a water-splitting system comprising a TiO2 photoanode and an organo-photocathode consisting of a p-n bilayer. Stoichiometric decomposition of water into H2 and O2 successfully occurred at bias voltages lower than the theoretical value (i.e. 1.23 V). Compared to the conventional TiO2 and Pt systems, the proposed water-splitting system demonstrated water splitting without any externally applied bias.

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Improvement of hydrogen evolution under visible light over Zn_1−2x(CuGa)_xGa₂S₄photocatalysts by synthesis utilizing a polymerizable complex method

Cited by 12 publications

References 51 publications

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

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

Electrochemical Synthesis of Photoelectrodes and Catalysts for Use in Solar Water Splitting

A water splitting system using an organo-photocathode and titanium dioxide photoanode capable of bias-free H₂ and O₂ evolution

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Improvement of hydrogen evolution under visible light over Zn1−2x(CuGa)xGa2S4photocatalysts by synthesis utilizing a polymerizable complex method

Cited by 12 publications

References 51 publications

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

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

Electrochemical Synthesis of Photoelectrodes and Catalysts for Use in Solar Water Splitting

A water splitting system using an organo-photocathode and titanium dioxide photoanode capable of bias-free H2 and O2 evolution

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Improvement of hydrogen evolution under visible light over Zn_1−2x(CuGa)_xGa₂S₄photocatalysts by synthesis utilizing a polymerizable complex method

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

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

A water splitting system using an organo-photocathode and titanium dioxide photoanode capable of bias-free H₂ and O₂ evolution