Porous CuBi<sub>2</sub>O<sub>4</sub> photocathodes with rationally engineered morphology and composition towards high-efficiency photoelectrochemical performance

Xu, Youxun; Jian, Jie; Li, Fan; Liu, Wei; Jia, Lichao; Wang, Hongqiang

doi:10.1039/c9ta07892d

Cited by 62 publications

(65 citation statements)

References 31 publications

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“…Therefore, the formation of single-phase pure CuBi 2 O 4 is not trivial, and the segregation of either CuO or Bi 2 O 3 would occur when Bi:Cu stoichiometry ≠ 2. [32] As expected, the most common impurities are CuO, [34,[49][50][51][52] and Bi 2 O 3 . [53][54][55][56] However, a nonstoichiometric Cu 0.84 Bi 2.08 O 4 was reported to form at low temperatures (≈200 °C) and to slowly decompose into Bi 2 O 3 and CuBi 2 O 4 at ≈400 °C.…”

Section: Introductionsupporting

confidence: 72%

Overcoming Phase‐Purity Challenges in Complex Metal Oxide Photoelectrodes: A Case Study of CuBi₂O₄

Gottesman

Levine

Schleuning

et al. 2021

Advanced Energy Materials

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fuel can be used on-site and on-demand but can also be stored and transported for off-site use. [5] However, practical PEC applications put stringent demands on photoabsorber materials in terms of efficiency, cost, and stability. Significant trade-offs have to be made, and this has thus far impeded the commercialization of PEC technology. [3,4] High solar to hydrogen conversion efficiencies approaching 20% have been achieved with photoelectrodes based on high-quality III-V semiconductors, such as GaInP 2 and GaAs. [6] However, their cost is likely to be prohibitive, and many of them suffer from instability under PEC operating conditions. The primary materials criteria are suitable bandgap energy to absorb a large fraction of solar photons with sufficient energies to enable water splitting, good electrical conductivity to enable photogenerated charge carrier extraction, favorable energy-band positions to enable carrier injection, and long-term stability in an aqueous environment. [4] Additionally, the material should be abundant and inexpensive in order to make PEC technology competitive with the chemical production of hydrogen from coal or natural gas. Almost all possible elemental and binary semiconductors have been investigated as photoelectrodes for water splitting, but none fulfill all the requirements. Therefore, the search will have to be expanded to ternary or even more complex materials. Metal-oxides offer many unique advantages as photoabsorber materials for PEC water splitting. [7-9] They have a variety of The widespread application of solar-water-splitting for energy conversion depends on the progress of photoelectrodes that uphold stringent criteria from photoabsorber materials. After investigating almost all possible elemental and binary semiconductors, the search must be expanded to complex materials. Yet, high structural control of these materials will become more challenging with an increasing number of elements. Complex metal-oxides offer unique advantages as photoabsorbers. However, practical fabrication conditions when using glass-based transparent conductive-substrates with low thermal-stability impedes the use of common synthesis routes of high-quality metal-oxide thin-film photoelectrodes. Nevertheless, rapid thermal processing (RTP) enables heating at higher temperatures than the thermal stabilities of the substrates, circumventing this bottleneck. Reported here is an approach to overcome phasepurity challenges in complex metal-oxides, showing the importance of attaining a single-phase multinary compound by exploring large growth parameter spaces, achieved by employing a combinatorial approach to study CuBi 2 O 4 , a prime candidate photoabsorber. Pure CuBi 2 O 4 photoelectrodes are synthesized after studying the relationship between the crystal-structures, synthesis conditions, RTP, and properties over a range of thicknesses. Single-phase photoelectrodes exhibit higher fill-factors, photoconversion efficiencies, longer carrier lifetimes, and increased stability than nonpure photoelectrodes...

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Section: Introductionsupporting

confidence: 72%

Overcoming Phase‐Purity Challenges in Complex Metal Oxide Photoelectrodes: A Case Study of CuBi₂O₄

Gottesman

Levine

Schleuning

et al. 2021

Advanced Energy Materials

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“…Generally, charge recombination occurs at the surface, interface and bulk of hematite, which lead to the sluggish carrier kinetics at both bulk, grain boundaries and interfaces of photoanode/electrolyte 126 . This section summarized the recent progress as well as significant achievements that aims to solve above issues based on the interface engineering for (i) the solid–liquid interface between the photoelectrode and electrolyte; (ii) the solid–solid interfaces of hematite.…”

Section: Interfacial Engineering Of the Hematite Photoanodementioning

confidence: 99%

Recent advances on interfacial engineering of hematite photoanodes for viable photo‐electrochemical water splitting

Jian

et al. 2021

Engineering Reports

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Oxygen evolution reaction (OER) occurring on photoanode is considered as the key step for photo‐electronchemical (PEC) water splitting. Among many potential photoanode materials, hematite (α‐Fe2O3) shows high promise considering its ideal band position, long‐term chemical stability, and earth abundance. Unfortunately, its sluggish oxygen evolution kinetics at photoanode/electrolyte interfaces and poor bulk charge transport limit the PEC performance. Herein, the most recent developments on interfacial engineering of hematite photoanode are summarized. We first describe the optical and electronic properties of the α‐Fe2O3 that are related to the PEC performance. Subsequently, we introduce the recent endeavors on the morphological engineering of the hematite photoanode. Then, the effective strategies of interfacial engineering are highlighted to address the limitations of α‐Fe2O3 photoanode at the surfaces and/or interfaces, as well as at the grain boundaries within the film. And the most recent progress of α‐Fe2O3 photoanode‐based tandem cells for self‐assisted overall water splitting is also discussed. Finally, an outlook is presented for future efforts on promoting the interfacial charge transport for boosted PEC performance of hematite‐based photo‐electrodes.

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“…[ 10 ] Efforts to overcome these drawbacks include modifying the FTO/CuBi 2 O 4 interface, [ 9,11,12 ] creating a gradient self‐doping in the CuBi 2 O 4 layer to improve the charge separation efficiency, and using thin protection layers. [ 5,13,14 ] To further improve the study and development of CuBi 2 O 4 photocathodes and to improve their photocurrent densities and stability, [ 15 ] it is necessary to fabricate them with high quality and purity, minimizing impurities and defects.…”

Section: Introductionmentioning

confidence: 99%

Pure CuBi₂O₄ Photoelectrodes with Increased Stability by Rapid Thermal Processing of Bi₂O₃/CuO Grown by Pulsed Laser Deposition

Gottesman

Song

Levine

et al. 2020

Adv Funct Materials

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A new method for enhancing the charge separation and photo-electrochemical stability of CuBi 2 O 4 photoelectrodes by sequentially depositing Bi 2 O 3 and CuO layers on fluorine-doped tin oxide substrates with pulsed laser deposition (PLD), followed by rapid thermal processing (RTP), resulting in phasepure, highly crystalline films after 10 min at 650 °C, is reported. Conventional furnace annealing of similar films for 72 h at 500 °C do not result in phasepure CuBi 2 O 4 . The combined PLD and RTP approach allow excellent control of the Bi:Cu stoichiometry and results in photoelectrodes with superior electronic properties compared to photoelectrodes fabricated through spray pyrolysis. The low photocurrents of the CuBi 2 O 4 photocathodes fabricated through PLD/RTP in this study are primarily attributed to their low specific surface area, lack of CuO impurities, and limited, slow charge transport in the undoped films. Bare (without protection layers) CuBi 2 O 4 photoelectrodes made with PLD/RTP shows a photocurrent decrease of only 26% after 5 h, which represents the highest stability reported to date for this material. The PLD/RTP fabrication approach offers new possibilities of fabricating complex metal oxides photoelectrodes with a high degree of crystallinity and good electronic properties at higher temperatures than the thermal stability of glass-based transparent conductive substrates would allow.

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Porous CuBi₂O₄ photocathodes with rationally engineered morphology and composition towards high-efficiency photoelectrochemical performance

Abstract: Nanoporous CuBi2O4 films with different chemical compositions and tunable band structures for high-efficiency photoelectrochemical performance.

Cited by 62 publications

References 31 publications

Overcoming Phase‐Purity Challenges in Complex Metal Oxide Photoelectrodes: A Case Study of CuBi₂O₄

Overcoming Phase‐Purity Challenges in Complex Metal Oxide Photoelectrodes: A Case Study of CuBi₂O₄

Recent advances on interfacial engineering of hematite photoanodes for viable photo‐electrochemical water splitting

Pure CuBi₂O₄ Photoelectrodes with Increased Stability by Rapid Thermal Processing of Bi₂O₃/CuO Grown by Pulsed Laser Deposition

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Porous CuBi2O4 photocathodes with rationally engineered morphology and composition towards high-efficiency photoelectrochemical performance

Abstract: Nanoporous CuBi2O4 films with different chemical compositions and tunable band structures for high-efficiency photoelectrochemical performance.

Cited by 62 publications

References 31 publications

Overcoming Phase‐Purity Challenges in Complex Metal Oxide Photoelectrodes: A Case Study of CuBi2O4

Overcoming Phase‐Purity Challenges in Complex Metal Oxide Photoelectrodes: A Case Study of CuBi2O4

Recent advances on interfacial engineering of hematite photoanodes for viable photo‐electrochemical water splitting

Pure CuBi2O4 Photoelectrodes with Increased Stability by Rapid Thermal Processing of Bi2O3/CuO Grown by Pulsed Laser Deposition

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Porous CuBi₂O₄ photocathodes with rationally engineered morphology and composition towards high-efficiency photoelectrochemical performance

Overcoming Phase‐Purity Challenges in Complex Metal Oxide Photoelectrodes: A Case Study of CuBi₂O₄

Overcoming Phase‐Purity Challenges in Complex Metal Oxide Photoelectrodes: A Case Study of CuBi₂O₄

Pure CuBi₂O₄ Photoelectrodes with Increased Stability by Rapid Thermal Processing of Bi₂O₃/CuO Grown by Pulsed Laser Deposition