Energy transfer-enhanced photocatalytic reduction of protons within quantum dot light-harvesting–Catalyst assemblies

Mohamad S. Kodaimati, Shichen Lian, George C Schatz, Emily A Weiss

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Excitonic energy transfer (EnT) is the mechanism by which natural photosynthetic systems funnel energy from hundreds of antenna pigments to a single reaction center, which allows multielectron redox reactions to proceed with high efficiencies in low-flux natural light. This paper describes the use of electrostatically assembled CdSe quantum dot (QD) aggregates as artificial light harvesting–reaction center units for the photocatalytic reduction of H+ to H2, where excitons are funneled through EnT from sensitizer QDs (sQDs) to catalyst QDs (cQDs). Upon increasing the sensitizer-to-catalyst ratio in the aggregates from 1:2 to 20:1, the number of excitons delivered to each cQD (via EnT) per excitation of the system increases by a factor of nine. At the optimized sensitizer-to-catalyst ratio of 4:1, the internal quantum efficiency (IQE) of the reaction system is 4.0 ± 0.3%, a factor of 13 greater than the IQE of a sample that is identical except that EnT is suppressed due to the relative core sizes of the sQDs and cQDs. A kinetic model supports the proposed exciton funneling mechanism for enhancement of the catalytic activity.

Original languageEnglish
Pages (from-to)8290-8295
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume115
Issue number33
DOIs
Publication statusPublished - Aug 14 2018

Fingerprint

Energy transfer
Semiconductor quantum dots
Protons
Catalysts
Quantum efficiency
Redox reactions
Catalyst supports
Pigments
Catalyst activity
Antennas
Fluxes
Kinetics
LDS 751

Keywords

  • Artificial photosynthesis
  • Energy transfer
  • Proton reduction
  • Quantum dot assemblies

ASJC Scopus subject areas

  • General

Cite this

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abstract = "Excitonic energy transfer (EnT) is the mechanism by which natural photosynthetic systems funnel energy from hundreds of antenna pigments to a single reaction center, which allows multielectron redox reactions to proceed with high efficiencies in low-flux natural light. This paper describes the use of electrostatically assembled CdSe quantum dot (QD) aggregates as artificial light harvesting–reaction center units for the photocatalytic reduction of H+ to H2, where excitons are funneled through EnT from sensitizer QDs (sQDs) to catalyst QDs (cQDs). Upon increasing the sensitizer-to-catalyst ratio in the aggregates from 1:2 to 20:1, the number of excitons delivered to each cQD (via EnT) per excitation of the system increases by a factor of nine. At the optimized sensitizer-to-catalyst ratio of 4:1, the internal quantum efficiency (IQE) of the reaction system is 4.0 ± 0.3{\%}, a factor of 13 greater than the IQE of a sample that is identical except that EnT is suppressed due to the relative core sizes of the sQDs and cQDs. A kinetic model supports the proposed exciton funneling mechanism for enhancement of the catalytic activity.",
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AU - Kodaimati, Mohamad S.

AU - Lian, Shichen

AU - Schatz, George C

AU - Weiss, Emily A

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AB - Excitonic energy transfer (EnT) is the mechanism by which natural photosynthetic systems funnel energy from hundreds of antenna pigments to a single reaction center, which allows multielectron redox reactions to proceed with high efficiencies in low-flux natural light. This paper describes the use of electrostatically assembled CdSe quantum dot (QD) aggregates as artificial light harvesting–reaction center units for the photocatalytic reduction of H+ to H2, where excitons are funneled through EnT from sensitizer QDs (sQDs) to catalyst QDs (cQDs). Upon increasing the sensitizer-to-catalyst ratio in the aggregates from 1:2 to 20:1, the number of excitons delivered to each cQD (via EnT) per excitation of the system increases by a factor of nine. At the optimized sensitizer-to-catalyst ratio of 4:1, the internal quantum efficiency (IQE) of the reaction system is 4.0 ± 0.3%, a factor of 13 greater than the IQE of a sample that is identical except that EnT is suppressed due to the relative core sizes of the sQDs and cQDs. A kinetic model supports the proposed exciton funneling mechanism for enhancement of the catalytic activity.

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