Controlled assembly of hydrogenase-CdTe nanocrystal hybrids for solar hydrogen production

Katherine A. Brown, Smita Dayal, Xin Ai, Gary Rumbles, Paul W. King

Research output: Contribution to journalArticle

159 Citations (Scopus)

Abstract

We present a study of the self-assembly, charge-transfer kinetics, and catalytic properties of hybrid complexes of CdTe nanocrystals (nc-CdTe) and Clostridium acetobutylicum [FeFe]-hydrogenase I (H2ase). Molecular assembly of nc-CdTe and H2ase was mediated by electrostatic interactions and resulted in stable, enzymatically active complexes. The assembly kinetics was monitored by nc-CdTe photoluminescence (PL) spectroscopy and exhibited first-order Langmuir adsorption behavior. PL was also used to monitor the transfer of photogenerated electrons from nc-CdTe to H 2ase. The extent to which the intramolecular electron transfer (ET) contributed to the relaxation of photoexcited nc-CdTe relative to the intrinsic radiative and nonradiative (heat dissipation and surface trapping) recombination pathways was shown by steady-state PL spectroscopy to be a function of the nc-CdTe/H2ase molar ratio. When the H2ase concentration was lower than the nc-CdTe concentration during assembly, the resulting contribution of ET to PL bleaching was enhanced, which resulted in maximal rates of H2 photoproduction. Photoproduction of H2 was also a function of the nc-CdTe PL quantum efficiency (PLQE), with higher-PLQE nanocrystals producing higher levels of H2, suggesting that photogenerated electrons are transferred to H2ase directly from core nanocrystal states rather than from surface-trap states. The duration of H 2 photoproduction was limited by the stability of nc-CdTe under the reactions conditions. A first approach to optimization with ascorbic acid present as a sacrificial donor resulted in photon-to-H2 efficiencies of 9% under monochromatic light and 1.8% under AM 1.5 white light. In summary, nc-CdTe and H2ase spontaneously assemble into complexes that upon illumination transfer photogenerated electrons from core nc-CdTe states to H2ase, with low H2ase coverages promoting optimal orientations for intramolecular ET and solar H2 production.

Original languageEnglish
Pages (from-to)9672-9680
Number of pages9
JournalJournal of the American Chemical Society
Volume132
Issue number28
DOIs
Publication statusPublished - Jul 21 2010

Fingerprint

Hydrogenase
Hydrogen production
Nanoparticles
Nanocrystals
Hydrogen
Electrons
Photoluminescence
Photoluminescence spectroscopy
Quantum efficiency
Spectrum Analysis
Clostridium acetobutylicum
Light
Clostridium
Kinetics
Ascorbic acid
Bleaching
Coulomb interactions
Lighting
Static Electricity
Heat losses

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Controlled assembly of hydrogenase-CdTe nanocrystal hybrids for solar hydrogen production. / Brown, Katherine A.; Dayal, Smita; Ai, Xin; Rumbles, Gary; King, Paul W.

In: Journal of the American Chemical Society, Vol. 132, No. 28, 21.07.2010, p. 9672-9680.

Research output: Contribution to journalArticle

Brown, Katherine A. ; Dayal, Smita ; Ai, Xin ; Rumbles, Gary ; King, Paul W. / Controlled assembly of hydrogenase-CdTe nanocrystal hybrids for solar hydrogen production. In: Journal of the American Chemical Society. 2010 ; Vol. 132, No. 28. pp. 9672-9680.
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