Diameter Dependent Electron Transfer Kinetics in Semiconductor鈥揈nzyme Complexes

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• 作者：Katherine A. Brown ; Qing Song ; David W. Mulder ; Paul W. King
• 刊名：ACS Nano
• 出版年：2014
• 出版时间：October 28, 2014
• 年：2014
• 卷：8
• 期：10
• 页码：10790-10798
• 全文大小：514K
• ISSN：1936-086X

文摘

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鈥?.5 nm diameter range of CdTe nanoparticles, the observed ET rate (k_ET) 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 k_ET values that were insensitive to diameter, despite a decrease in the free energy for photoexcited ET (螖G_ET) with increasing diameter. The turnover frequency (TOF) of CaI in CdTe鈥揅aI 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 k_ET and H₂ production for CdTe鈥揅aI complexes are not strictly controlled by 螖G_ET and that other factors must be considered.

Keywords:

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