A Bismuth Vanadate–Cuprous Oxide Tandem Cell for Overall Solar Water Splitting

Bornoz, Pauline; Abdi, Fatwa F.; Tilley, S. David; Dam, B.; Krol, Roel van de; Gräetzel, Michael; Sivula, Kevin

doi:10.1021/jp500441h

Cited by 240 publications

(193 citation statements)

References 39 publications

(90 reference statements)

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“…60 This flat band potential is close to the values typically reported for BVO. 9,34,56 The noMo/T devices (blue traces) have a significantly better photocurrent onset (0. show below that the overall, spectrally integrated internal quantum efficiency of these Mo/T electrodes for sulfite oxidation at the OER potential (IQE = Z t = J/J abs ) is 70 AE 5%, limited by hole transport, and that the difference between the EE and SE photocurrents is due primarily to absorption losses in the FTO-coated glass substrate in the SE geometry. Recently, Seabold et al reported very similar results to our own -including a total IQE as high as 90% and larger photocurrent under EE than SE illumination -using 100-300 nm thick Mo:BVO films with a nanoporous morphology comparable to our films but without [001] texture.…”

Section: àmentioning

confidence: 99%

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Textured nanoporous Mo:BiVO₄ photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

Nair

Perkins

Lin

et al. 2016

Energy Environ. Sci.

148

106

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We have developed a simple spin coating method to make high-quality nanoporous photoelectrodes of monoclinic BiVO 4 and studied the ability of these electrodes to transport photogenerated carriers to oxidize sulfite and water. Samples containing molybdenum and featuring [001] out-of-plane crystallographic texture show a photocurrent and external quantum efficiency (EQE) for sulfite oxidation as high as 3.1 mA cm À2 and 60%, respectively, at 1.23 V versus reversible hydrogen electrode. By using an optical model of the electrode stack to accurately determine the fraction of electrode absorptance due to the BiVO 4 active layer, we estimate that on average 70 AE 5% of all photogenerated carriers escape recombination. A comparison of internal quantum efficiency as a function of film processing, illumination direction, and film thickness shows that electron transport is efficient and hole transport limits the photocurrent (hole diffusion length o40 nm). We find that Mo addition primarily improves electron transport and texturing mostly improves hole transport. Mo enhances electron transport by thinning the surface depletion layer or passivating traps and recombination centers at grain boundaries and interfaces, while improved hole transport in textured films may result from more efficient lateral hole extraction due to the texturing itself or the reduced density of deep gap states observed in photoemission measurements.Photoemission data also reveal that the films have bismuth-rich, vanadium-and oxygen-deficient surface layers, while ion scattering spectroscopy indicates a Bi-V-O surface termination. Without added catalysts, the plain BiVO 4 electrodes oxidized water with an initial photocurrent and peak EQE of 1.7 mA cm À2 and 30%, respectively, which equates to a hole transfer efficiency to water of 464% at 1.23 V. The electrodes quickly photocorrode during water oxidation but show good stability during sulfite oxidation and indefinite stability in the dark. By improving the hole transport efficiency and coating these nanoporous BiVO 4 films with an appropriate protective layer and oxygen evolution catalyst, it should be possible to achieve highly efficient and stable water oxidation at a practical pH.

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Section: àmentioning

confidence: 99%

“…phosphate, CoO x , metal oxyhydroxides) 8,9,14,18,[20][21][22]25,30,37,39,[50][51][52][53][54][55][56] to promote water oxidation and enhance BVO stability. Comparatively little work has been done to understand and optimize the light absorption, charge transport, and charge transfer properties of BVO itself.…”

Section: Introductionmentioning

confidence: 99%

Textured nanoporous Mo:BiVO₄ photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

Nair

Perkins

Lin

et al. 2016

Energy Environ. Sci.

148

106

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“…By forming an electrical connection between these two electrodes, their individual potentials for driving water splitting reactions can be simply combined. [9][10][11][12] In such a system, a plausible working potential for the photoanode and photocathode is about 0.6 V RHE , and both electrodes need to generate a sufficient photocurrent at this potential to achieve efficient water splitting.…”

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

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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“…3 At the other end of the spectrum are oxide-based devices, which can be cheap but show poor efficiencies. 4 Further development of these preprototype systems is needed as a precursor to the required industrial level scale-up to enable solar fuels to have a real impact. In this perspective, we will attempt to evaluate where the field has progressed and where there is still a need for breakthroughs to produce a viable solar fuels industry.…”

Section: Introductionmentioning

confidence: 99%

Perspectives on the photoelectrochemical storage of solar energy

Krol

Parkinson

2017

MRS Energy & Sustainability

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Direct photoelectrochemical water splitting offers several advantages over PV-powered electrolysis and may become the technology of choice in the future. However, significant R&D efforts and breakthroughs are needed to accomplish this goal.The sustainable production of hydrogen would be an important first step for both powering fuel cells and for enabling large-scale and technologically mature gas phase processes to reduce CO 2 and nitrogen to get desired products. Specifically, the central challenge is to produce hydrogen from water using sunlight. Photovoltaics and wind-powered electrolysis are likely to be the technology of choice to produce renewable hydrogen for the next few decades. However, the integration of light absorption and catalysis in 'direct' photoelectrolysis routes offers several advantages, such as lower current densities and better heat management, and may become technologically relevant in the second half of this century. This article discusses the research and development efforts and needed breakthroughs to achieve this goal. New chemically stable semiconductors with a band gap between 1.5 and 2.0 eV and long carrier lifetimes are urgently needed to make efficient tandem devices.Scale-up of these research level devices beyond a few cm 2 introduces mass transport limitations that require creative electrochemical engineering solutions. Last but not least, standardized methods for measuring efficiencies and stabilities need to be implemented and should lead to official benchmarking and certification laboratories to guide commercial scale up efforts. Keywords: photochemical; energy storage; energy generation RevIew DISCUSSION POINTS• Water splitting will be a central challenge for any future fossil fuel-free energy infrastructure that relies on liquid or gaseous chemical fuels.• While the main materials challenge for solar-and wind-driven electrolysis is the development of better catalysts, the main challenge for photoelectrochemical water splitting is to find new chemically stable optimal-bandgap semiconducting light absorbers.• Further progress in the development of photo-driven water splitting generators requires significant additional efforts in electrochemical engineering and the development of standardized methods for benchmarking device performance and stability.

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A Bismuth Vanadate–Cuprous Oxide Tandem Cell for Overall Solar Water Splitting

Cited by 240 publications

References 39 publications

Textured nanoporous Mo:BiVO₄ photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

Textured nanoporous Mo:BiVO₄ photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

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

Perspectives on the photoelectrochemical storage of solar energy

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A Bismuth Vanadate–Cuprous Oxide Tandem Cell for Overall Solar Water Splitting

Cited by 240 publications

References 39 publications

Textured nanoporous Mo:BiVO4 photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

Textured nanoporous Mo:BiVO4 photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

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

Perspectives on the photoelectrochemical storage of solar energy

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Product

Resources

About

Textured nanoporous Mo:BiVO₄ photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

Textured nanoporous Mo:BiVO₄ photoanodes with high charge transport and charge transfer quantum efficiencies for oxygen evolution

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