WO<sub>3</sub>/BiVO<sub>4</sub>: impact of charge separation at the timescale of water oxidation

Selim, Shababa; Francàs, Laia; García‐Tecedor, Miguel; Corby, Sacha; Blackman, Christopher S.; Giménez, Sixto; Durrant, James R.; Kafizas, Andreas

doi:10.1039/c8sc04679d

Cited by 79 publications

(74 citation statements)

References 48 publications

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“…Photoelectrochemical water oxidation performance of the photoanodes is presented in Figure S3b, and is typical of such photoanodes reported in the literature. 19,37…”

Section: Resultsmentioning

confidence: 99%

Impact of Oxygen Vacancy Occupancy on Charge Carrier Dynamics in BiVO₄ Photoanodes

et al. 2019

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Oxygen vacancies are ubiquitous in metal oxides and critical to performance, yet the impact of these states upon charge carrier dynamics important for photoelectrochemical and photocatalytic applications, remains contentious and poorly understood. A key challenge is the unambiguous identification of spectroscopic fingerprints which can be used to track their function. Herein, we employ five complementary techniques to modulate the electronic occupancy of states associated with oxygen vacancies in situ in BiVO4 photoanodes, allowing us to identify a spectral signature for the ionisation of these states. We obtain an activation energy of ̴ 0.2 eV for this ionisation process, with thermally activated electron de-trapping from these states determining the kinetics of electron extraction, consistent with improved photoelectrochemical performance at higher temperatures. Bulk, un-ionised states however, function as deep hole traps, with such trapped holes being energetically unable to drive water oxidation. These observations help address recent controversies in the literature over oxygen vacancy function, providing new insights into their impact upon photoelectrochemical performance.

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“…Photoelectrochemical water oxidation performance of the photoanodes is presented in Figure S3b, and is typical of such photoanodes reported in the literature. 19,37…”

Section: Resultsmentioning

confidence: 99%

Impact of Oxygen Vacancy Occupancy on Charge Carrier Dynamics in BiVO₄ Photoanodes

et al. 2019

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“…The band alignment allows photoelectrons to flow from the BiVO 4 to the WO 3 domain, leaving the photoholes in the BiVO 4 domain to conduct a water oxidation reaction. Selim et al [80] reported the interfacial charge dynamics of WO 3 /BiVO 4 by using in situ TA spectroscopy. Figure 5A and B shows the TA spectra under 1.23 V (vs. RHE) and OCP at 10 µs and 10 ms after excitation.…”

Section: Bivo 4 Photoanodesmentioning

confidence: 99%

In situ charge carrier dynamics of semiconductor nanostructures for advanced photoelectrochemical and photocatalytic applications

2020

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Using in situ ultrafast laser spectroscopic techniques to monitor the charge dynamics of semiconductor photocatalysts under operating conditions is essential for digging out the veritable interactions between charge carriers and the reactive species. This real-time observation is desirable for optimizing individual components and their integration in advanced photoelectrochemical (PEC) and photocatalytic systems, which can achieve the “Holy Grail” of solar energy harvesting and solar fuel generation. This Review summarizes the recent developments of employing transient absorption spectroscopy for in situ measurements of charge dynamics on semiconductor nanostructures. The implications in the PEC and photocatalytic reactions toward hydrogen production and carbon dioxide reduction will be discussed, along with future outlooks and perspectives.

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“…Many pairings of inorganic heterojunctions have been investigated for PEC water splitting, including anatase TiO 2 /rutile TiO 2 , [ 244 ] Cu 2 O/TiO 2 , [ 206 ] and ZnO/α‐Fe 2 O 3 . [ 282 ] However, one of the most popular pairings is WO 3 /BiVO 4 for use as photoanodes. [ 283 ] The band energies of WO 3 and BiVO 4 align in a staggered type II fashion, shown in Figure 20 , where the transfer of electrons formed in BiVO 4 into WO 3 , and the transfer of holes formed in WO 3 into BiVO 4 , are both thermodynamically favorable, and therefore drive the spatial separation of charge.…”

Section: Materials Choice For Pec Water Splittingmentioning

confidence: 99%

“…[ 96 ] The high efficiency in this system has been attributed to the fast (sub‐microsecond) transfer of electrons formed in BiVO 4 into WO 3 , thereby sufficiently prolonging the lifetime of the holes that remain in BiVO 4 to oxidize water (approximately milliseconds to seconds). [ 282 ]…”

Section: Materials Choice For Pec Water Splittingmentioning

confidence: 99%

A Review of Inorganic Photoelectrode Developments and Reactor Scale‐Up Challenges for Solar Hydrogen Production

Moss

Babacan

Kafizas

et al. 2021

Advanced Energy Materials

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Green hydrogen, produced using solar energy, is a promising means of reducing greenhouse gas emissions. Photoelectrochemical (PEC) water splitting devices can produce hydrogen using sunlight and integrate the distinct functions of photovoltaics and electrolyzers in a single device. There is flexibility in the degree of integration between these electrical and chemical energy generating components, and so a plethora of archetypal PEC device designs has emerged. Although some materials have effectively been ruled out for use in commercial PEC devices, many principles of material design and synthesis have been learned. Here, the fundamental requirements of PEC materials, the top performances of the most widely studied inorganic photoelectrode materials, and reactor structures reported for unassisted solar water splitting are revisited. The main phenomena limiting the performance of up‐scaled PEC devices are discussed, showing that engineering must be considered in parallel with material development for the future piloting of PEC water splitting systems. To establish the future commercial viability of this technology, more accurate techno‐economic analyses should be carried out using data from larger scale demonstrations, and hence more durable and efficient PEC systems need to be developed that meet the challenges imposed from both material and engineering perspectives.

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WO₃/BiVO₄: impact of charge separation at the timescale of water oxidation

Abstract: Unveiling the role of applied bias on the charge carrier dynamics in the WO3/BiVO4 junction during water oxidation.

Cited by 79 publications

References 48 publications

Impact of Oxygen Vacancy Occupancy on Charge Carrier Dynamics in BiVO₄ Photoanodes

Impact of Oxygen Vacancy Occupancy on Charge Carrier Dynamics in BiVO₄ Photoanodes

In situ charge carrier dynamics of semiconductor nanostructures for advanced photoelectrochemical and photocatalytic applications

A Review of Inorganic Photoelectrode Developments and Reactor Scale‐Up Challenges for Solar Hydrogen Production

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WO3/BiVO4: impact of charge separation at the timescale of water oxidation

Abstract: Unveiling the role of applied bias on the charge carrier dynamics in the WO3/BiVO4 junction during water oxidation.

Cited by 79 publications

References 48 publications

Impact of Oxygen Vacancy Occupancy on Charge Carrier Dynamics in BiVO4 Photoanodes

Impact of Oxygen Vacancy Occupancy on Charge Carrier Dynamics in BiVO4 Photoanodes

In situ charge carrier dynamics of semiconductor nanostructures for advanced photoelectrochemical and photocatalytic applications

A Review of Inorganic Photoelectrode Developments and Reactor Scale‐Up Challenges for Solar Hydrogen Production

Contact Info

Product

Resources

About

WO₃/BiVO₄: impact of charge separation at the timescale of water oxidation

Impact of Oxygen Vacancy Occupancy on Charge Carrier Dynamics in BiVO₄ Photoanodes

Impact of Oxygen Vacancy Occupancy on Charge Carrier Dynamics in BiVO₄ Photoanodes