Size-dependent photocatalytic activity of carbon dots with surface-state determined photoluminescence

Yiqun Zhou, Elsayed M. Zahran, Bruno A. Quiroga, Jennifer Perez, Keenan J. Mintz, Zhili Peng, Piumi Y. Liyanage, Raja R. Pandey, Charles C. Chusuei, Roger M. Leblanc

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

Carbon dots (CDs) were synthesized by a microwave-mediated method and separated by size exclusion chromatography into three different size fractions. There was no correlation of CD size with photoluminescence (PL) emission wavelength, showing that the PL mechanism is not quantum-size dependent. UV/vis absorption and diffuse reflectance spectroscopies showed that the light absorption properties as well as the band gap of the CDs changed with the size of the particle. The combination of FTIR and XPS measurements revealed the composition on the surface of each fraction. The three CDs fractions were separately used in the photocatalytic degradation of organic dyes under simulated sunlight irradiation. The catalytic activity of the as-prepared CDs was found to increase as the size of the particles decreased. Complete degradation of both rhodamine B (RhB) and methylene blue (MB) was achieved in 150 min by the 2-nm CDs. The scavenger studies showed that the holes and superoxide radicals are the main species involved in the photocatalytic degradation of the dye by the 2-nm CDs. These CDs displayed high stability in the degradation of organic dyes for multiple cycles. The 2-nm CDs displayed promising photocatalytic degradation of p-nitrophenol (PNP). These results demonstrate for the first time the application of bare carbon dots in the degradation of environmental contaminants.

Original languageEnglish (US)
Pages (from-to)157-166
Number of pages10
JournalApplied Catalysis B: Environmental
Volume248
DOIs
StatePublished - Jul 5 2019

Keywords

  • Carbon dots
  • Organic compound degradation
  • Photocatalysis
  • Photoluminescence
  • ROS

ASJC Scopus subject areas

  • Catalysis
  • Environmental Science(all)
  • Process Chemistry and Technology

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