Colloidally Stable CdS Quantum Dots in Water with Electrostatically Stabilized Weak-Binding, Sulfur-Free Ligands

Francesca Arcudi, Dana Emily Westmoreland, Emily Allyn Weiss

Research output: Contribution to journalArticlepeer-review

Abstract

Colloidal quantum dot (QD) photocatalysts have the electrochemical and optical properties to be highly effective for a range of redox reactions. QDs are proven photo-redox catalysts for a variety of reactions in organic solvents but are less prominent for aqueous reactions. Aqueous QD photocatalysts require hydrophilic ligand shells that provide long-term colloidal stability but are not so tight-binding as to prevent catalytic substrates from accessing the QD surface. Common thiolate ligands, which also poison many co-catalysts and undergo photo-oxidative desorption, are therefore often not an option. This paper describes a framework for the design of water-solubilizing ligands that are in dynamic exchange on and off the QD surface, but still provide long-term colloidal stability to CdS QDs. The binding affinity and inter-ligand electrostatic interactions of a bifunctional ligand, aminoethyl phosphonic acid (AEP), are tuned with the pH of the dispersion. The key to colloidal stability is electrostatic stabilization of the monolayer. This work demonstrates a means of mimicking the stabilizing power of a thiolate-bound ligand with a zwitterionic tail group, but without the thiolate binding group.

Original languageEnglish
Pages (from-to)14469-14474
Number of pages6
JournalChemistry - A European Journal
Volume25
Issue number63
DOIs
Publication statusPublished - Nov 13 2019

Keywords

  • catalysis
  • ligand design
  • nanotechnology
  • quantum dots
  • water chemistry

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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