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Research on the surface chemistry of quantum dots (QDs) has been rapidly developing in recent years, since the
understanding of the processes that occur on their surface is prerequisite for successful exploration of the outstanding
fluorescence properties and superior stability of these nanomaterials in numerous applications. The lack of stability
during long-term storage under atmospheric conditions restricts QD applications. Here, we have investigated the
interaction of QDs with carbon dioxide as a model system for studying their long-term storage or operation in
atmospheric environment. Quenching of the photoluminescence of CdSe/ZnS semiconductor QDs continuously treated
with CO2 has shown that this process depends on the type of the QD surface ligands. The luminescence of QDs capped
with amine ligands is quenched to a higher degree, the quenching being caused by the formation of carbamic acid
precipitate. The luminescence of QDs capped with thiols remain absolutely stable upon CO2 treatment due to the
chemical resistance of thiol functional groups to CO2, which makes this type of QDs suitable for long-term storage and
operation under atmospheric conditions. However, further functionalization of such QDs may be difficult, because the
strong bond between thiol ligands and QD surface may limit the efficiency of ligand-exchange procedures. A new ligand
system of alkylamine salts of fatty acids has been proposed as an alternative to thiols. It has been shown to be inert to
CO2, and also can be easily replaced with functional surface ligands. The results are important for development of nextgeneration
QDs with superior stability suitable for various applications requiring efficient ligand exchange and operation
in the atmospheric environment.
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