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Dynamic Role of Cluster Cocatalysts on Molecular Photoanodes for Water Oxidation


Li, Jingguo; Wan, Wenchao; Triana, C A; Novotny, Zbynek; Osterwalder, Jürg; Erni, Rolf; Patzke, Greta R (2019). Dynamic Role of Cluster Cocatalysts on Molecular Photoanodes for Water Oxidation. Journal of the American Chemical Society, 141(32):12839-12848.

Abstract

While loading of cocatalysts is one of the most widely investigated strategies to promote the efficiency of photoelectrodes, the understanding of their functionality remains controversial. We established new hybrid molecular photoanodes with cobalt-based molecular cubane cocatalysts on hematite as a model system. Photoelectrochemical and rate law analyses revealed an interesting functionality transition of the {Co(II)4O4}-type cocatalysts. Their role changed from predominant hole reservoirs to catalytic centers upon modulation of the applied bias. Kinetic analysis of the photoelectrochemical processes indicated that this observed transition arises from the dynamic equilibria of photogenerated surface charge carriers. Most importantly, we confirmed this functional transition of the cocatalysts and the related kinetic properties for several cobalt-based molecular and heterogeneous catalysts, indicating wide applicability of the derived trends. Additionally, complementary analytical characterizations show that a transformation of the applied molecular species occurs at higher applied bias, pointing to a dynamic interplay connecting molecular and heterogeneous catalysis. Our insights promote the essential understanding of efficient (molecular) cocatalyzed photoelectrode systems to design tailor-made hybrid devices for a wide range of catalytic applications.

Abstract

While loading of cocatalysts is one of the most widely investigated strategies to promote the efficiency of photoelectrodes, the understanding of their functionality remains controversial. We established new hybrid molecular photoanodes with cobalt-based molecular cubane cocatalysts on hematite as a model system. Photoelectrochemical and rate law analyses revealed an interesting functionality transition of the {Co(II)4O4}-type cocatalysts. Their role changed from predominant hole reservoirs to catalytic centers upon modulation of the applied bias. Kinetic analysis of the photoelectrochemical processes indicated that this observed transition arises from the dynamic equilibria of photogenerated surface charge carriers. Most importantly, we confirmed this functional transition of the cocatalysts and the related kinetic properties for several cobalt-based molecular and heterogeneous catalysts, indicating wide applicability of the derived trends. Additionally, complementary analytical characterizations show that a transformation of the applied molecular species occurs at higher applied bias, pointing to a dynamic interplay connecting molecular and heterogeneous catalysis. Our insights promote the essential understanding of efficient (molecular) cocatalyzed photoelectrode systems to design tailor-made hybrid devices for a wide range of catalytic applications.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
07 Faculty of Science > Physics Institute
08 Research Priority Programs > Solar Light to Chemical Energy Conversion
Dewey Decimal Classification:530 Physics
Scopus Subject Areas:Physical Sciences > Catalysis
Physical Sciences > General Chemistry
Life Sciences > Biochemistry
Physical Sciences > Colloid and Surface Chemistry
Uncontrolled Keywords:Colloid and Surface Chemistry, Biochemistry, General Chemistry, Catalysis
Language:English
Date:14 August 2019
Deposited On:17 Oct 2019 06:13
Last Modified:29 Jul 2020 11:28
Publisher:American Chemical Society (ACS)
ISSN:0002-7863
OA Status:Closed
Publisher DOI:https://doi.org/10.1021/jacs.9b06100
Project Information:
  • : FunderH2020
  • : Grant ID681312
  • : Project TitleCLUSTER - Birth of solids: atomic-scale processes in crystal nucleation
  • : FunderSNSF
  • : Grant IDCRSII2_160801
  • : Project TitlePhotocatalytic Processes at Solvated Interfaces

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