A simplified theoretical guideline for overall water splitting using photocatalyst particles

Handle URI:
http://hdl.handle.net/10754/621692
Title:
A simplified theoretical guideline for overall water splitting using photocatalyst particles
Authors:
Garcia Esparza, Angel T. ( 0000-0002-4884-171X ) ; Takanabe, Kazuhiro ( 0000-0001-5374-9451 )
Abstract:
Particulate photocatalytic water splitting is the most disruptive and competitive solution for the direct production of solar fuels. Despite more than four decades of work in the field of photocatalysis using powdered semiconductors decorated with catalyst particles, there is no clear consensus on the factors limiting the solar-to-hydrogen efficiency (STH). To understand the intrinsic limitations of the system, we numerically simulated simplified two-dimensional photocatalytic models using classical semiconductor device equations. This work presents the sensitivity of quantum efficiency (QE) to the various semiconductor properties, such as absorption properties and carrier mobilities, and to the dispersion of catalyst particles, which create heterojunctions, the driving force for charge separation. As a result, a pinch-off effect was prevalent underneath the hydrogen evolution site, suggesting an undesired energetic barrier for electron diffusion to the catalyst. The simulation using the values reported in the literature revealed that the QE was exclusively governed by recombination in the bulk of the photocatalyst particles, hindering the charge separation efficiency before reaching the catalysts on the surface. Using some of the reported parameters, our simulation shows that a typical defective n-type semiconductor particle (∼100 nm) ideally exhibits a QE of <5% in the visible light range per particle, which reaches only approximately 10% in a slurry after 4 consecutive absorbing units (1.4% STH, from simulated solar irradiation). Although the present model contains rigid limitations, we use these trends as an initial guideline to pursue photocatalysis by a design strategy, which may result in possible alternatives to achieve higher efficiencies. © 2016 The Royal Society of Chemistry.
KAUST Department:
KAUST Catalysis Center (KCC); Physical Sciences and Engineering (PSE) Division
Citation:
Garcia-Esparza AT, Takanabe K (2016) A simplified theoretical guideline for overall water splitting using photocatalyst particles. J Mater Chem A 4: 2894–2908. Available: http://dx.doi.org/10.1039/c5ta06983a.
Publisher:
Royal Society of Chemistry (RSC)
Journal:
J. Mater. Chem. A
Issue Date:
2-Oct-2015
DOI:
10.1039/c5ta06983a
Type:
Article
ISSN:
2050-7488; 2050-7496
Sponsors:
The research reported in this work was supported by the King Abdullah University of Science and Technology (KAUST).
Additional Links:
http://pubs.rsc.org/en/content/articlehtml/2016/ta/c5ta06983a
Appears in Collections:
Articles; Physical Sciences and Engineering (PSE) Division; KAUST Catalysis Center (KCC)

Full metadata record

DC FieldValue Language
dc.contributor.authorGarcia Esparza, Angel T.en
dc.contributor.authorTakanabe, Kazuhiroen
dc.date.accessioned2016-11-03T13:22:53Z-
dc.date.available2016-11-03T13:22:53Z-
dc.date.issued2015-10-02en
dc.identifier.citationGarcia-Esparza AT, Takanabe K (2016) A simplified theoretical guideline for overall water splitting using photocatalyst particles. J Mater Chem A 4: 2894–2908. Available: http://dx.doi.org/10.1039/c5ta06983a.en
dc.identifier.issn2050-7488en
dc.identifier.issn2050-7496en
dc.identifier.doi10.1039/c5ta06983aen
dc.identifier.urihttp://hdl.handle.net/10754/621692-
dc.description.abstractParticulate photocatalytic water splitting is the most disruptive and competitive solution for the direct production of solar fuels. Despite more than four decades of work in the field of photocatalysis using powdered semiconductors decorated with catalyst particles, there is no clear consensus on the factors limiting the solar-to-hydrogen efficiency (STH). To understand the intrinsic limitations of the system, we numerically simulated simplified two-dimensional photocatalytic models using classical semiconductor device equations. This work presents the sensitivity of quantum efficiency (QE) to the various semiconductor properties, such as absorption properties and carrier mobilities, and to the dispersion of catalyst particles, which create heterojunctions, the driving force for charge separation. As a result, a pinch-off effect was prevalent underneath the hydrogen evolution site, suggesting an undesired energetic barrier for electron diffusion to the catalyst. The simulation using the values reported in the literature revealed that the QE was exclusively governed by recombination in the bulk of the photocatalyst particles, hindering the charge separation efficiency before reaching the catalysts on the surface. Using some of the reported parameters, our simulation shows that a typical defective n-type semiconductor particle (∼100 nm) ideally exhibits a QE of <5% in the visible light range per particle, which reaches only approximately 10% in a slurry after 4 consecutive absorbing units (1.4% STH, from simulated solar irradiation). Although the present model contains rigid limitations, we use these trends as an initial guideline to pursue photocatalysis by a design strategy, which may result in possible alternatives to achieve higher efficiencies. © 2016 The Royal Society of Chemistry.en
dc.description.sponsorshipThe research reported in this work was supported by the King Abdullah University of Science and Technology (KAUST).en
dc.publisherRoyal Society of Chemistry (RSC)en
dc.relation.urlhttp://pubs.rsc.org/en/content/articlehtml/2016/ta/c5ta06983aen
dc.titleA simplified theoretical guideline for overall water splitting using photocatalyst particlesen
dc.typeArticleen
dc.contributor.departmentKAUST Catalysis Center (KCC)en
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
dc.identifier.journalJ. Mater. Chem. Aen
kaust.authorGarcia Esparza, Angel T.en
kaust.authorTakanabe, Kazuhiroen
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