Fabrication, gradient extraction and surface polarity-dependent photoluminescence of cow milk-derived carbon dots

Shuai Han, He Zhang, Jian Zhang, Yujie Xie, Liangliang Liu, Hangxing Wang, Xiangkai Li, Weisheng Liu, Yu Tang

Research output: Contribution to journalArticle

18 Scopus citations


Cow milk-derived carbon dots (CMCD) were separated using a simple and cheap "gradient extraction" method, which was applied for the first time in nanomaterials' separation. The surface polarity of the extracted CMCD correlates well with the polarity of the extraction solvent. Interestingly, the surface polarity also affects the photoluminescence (PL) of CMCD: a red-shift of PL was observed as the surface polarity increased, which was attributed to the increasing amount of polar functional groups on the surface as auxochromes which are bound to graphitic sp2 clusters and reduce their energy gaps. Furthermore, as the surface polarity of CMCD increases, their PL exhibits longer lifetimes and a stronger excitation-dependency, which are attributed to the more efficient "internal" energy transfer from the auxochrome-poor sp2 clusters to the auxochrome-rich sp2 clusters of the CMCD.

Original languageEnglish (US)
Pages (from-to)58084-58089
Number of pages6
JournalRSC Advances
Issue number101
StatePublished - 2014


ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

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