Control of the Redox Activity of PbS Quantum Dots by Tuning Electrostatic Interactions at the Quantum Dot/Solvent Interface

Chen He, David J. Weinberg, Alexander B. Nepomnyashchii, Shichen Lian, Emily A Weiss

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

This paper describes the control of electron exchange between a colloidal PbS quantum dot (QD) and a negatively charged small molecule (9,10-anthraquinone-2-sulfonic acid sodium salt, AQ), through tuning of the charge density in the ligand shell of the QD, within an aqueous dispersion. The probability of electron exchange, measured through steady-state and time-resolved optical spectroscopy, is directly related to the permeability of the protective ligand shell, which is a mixed monolayer of negatively charged 6-mercaptohexanoate (MHA) and neutral 6-mercaptohexanol (MHO), to AQ. The composition of the ligand shell is quantitatively characterized by 1H NMR. The dependence of the change in Gibbs free energy, δGobs, for the diffusion of AQ through the charged ligand shell and its subsequent adsorption to the QD surface is well-described with an electrostatic double-layer model for the QD/solvent interface. Fits of the optical data to this model yield an increase in the free energy for transfer of AQ from bulk solution to the surface of the QD (where it exchanges electrons with the QD) of 154 J/mol upon introduction of each additional charged MHA ligand to the ligand shell. This work expands the set of chemical parameters useful for controlling the redox activity of QDs via surface modification and suggests strategies for the use of nanoparticles for molecular and biomolecular recognition within chemically complex environments and for design of chemically stable nanoparticles for aqueous photocatalytic systems.

Original languageEnglish
Pages (from-to)8847-8854
Number of pages8
JournalJournal of the American Chemical Society
Volume138
Issue number28
DOIs
Publication statusPublished - Jul 20 2016

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Quantum Dots
Coulomb interactions
Static Electricity
Semiconductor quantum dots
Oxidation-Reduction
Tuning
Ligands
Electrons
Nanoparticles
Environment Design
Energy Transfer
Gibbs free energy
Charge density
Free energy
Adsorption
Surface treatment
Electrostatics
Monolayers
Permeability
Spectrum Analysis

ASJC Scopus subject areas

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

Cite this

Control of the Redox Activity of PbS Quantum Dots by Tuning Electrostatic Interactions at the Quantum Dot/Solvent Interface. / He, Chen; Weinberg, David J.; Nepomnyashchii, Alexander B.; Lian, Shichen; Weiss, Emily A.

In: Journal of the American Chemical Society, Vol. 138, No. 28, 20.07.2016, p. 8847-8854.

Research output: Contribution to journalArticle

He, Chen ; Weinberg, David J. ; Nepomnyashchii, Alexander B. ; Lian, Shichen ; Weiss, Emily A. / Control of the Redox Activity of PbS Quantum Dots by Tuning Electrostatic Interactions at the Quantum Dot/Solvent Interface. In: Journal of the American Chemical Society. 2016 ; Vol. 138, No. 28. pp. 8847-8854.
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