Diameter Dependent Electron Transfer Kinetics in Semiconductor-Enzyme Complexes

Paul King, Katherine Brown, David Mulder, Qing Song

Research output: Contribution to journalArticlepeer-review

32 Scopus Citations


Excited state electron transfer (ET) is a fundamental step for the catalytic conversion of solar energy into chemical energy. To understand the properties controlling ET between photoexcited nanoparticles and catalysts, the ET kinetics were measured for solution-phase complexes of CdTe quantum dots and Clostridium acetobutylicum [FeFe]-hydrogenase I (CaI) using time-resolved photoluminescence spectroscopy. Over a 2.0-3.5 nm diameter range of CdTe nanoparticles, the observed ET rate (kET) was sensitive to CaI concentration. To account for diameter effects on CaI binding, a Langmuir isotherm and two geometric binding models were created to estimate maximal CaI affinities and coverages at saturating concentrations. Normalizing the ET kinetics to CaI surface coverage for each CdTe diameter led to kET values that were insensitive to diameter, despite a decrease in the free energy for photoexcited ET (ΔGET) with increasing diameter. The turnover frequency (TOF) of CaI in CdTe-CaI complexes was measured at several molar ratios. Normalization for diameter-dependent changes in CaI coverage showed an increase in TOF with diameter. These results suggest that kET and H2 production for CdTe-CaI complexes are not strictly controlled by ΔGET and that other factors must be considered.

Original languageAmerican English
Pages (from-to)10790-10798
Number of pages9
JournalACS Nano
Issue number10
StatePublished - 2014

Bibliographical note

Publisher Copyright:
© 2014 American Chemical Society.

NREL Publication Number

  • NREL/JA-2700-62598


  • binding complex
  • biohybrid
  • hydrogen
  • interfacial electron-transfer
  • nanoparticle
  • photochemical


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