Fluorescence of functionalized graphene quantum dots prepared from infrared-assisted pyrolysis of citric acid and urea

Siyong Gu, Chien Te Hsieh*, Chun Yao Yuan, Yasser Ashraf Gandomi, Jeng-Kuei Chang*, Chun Chieh Fu, Jou Wen Yang, Ruey Shin Juang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

71 Scopus citations


This paper reports an efficient fabrication of N-doped graphene quantum dots (GQDs) showing controllable chemical and fluorescence (FL) properties through infrared carbonization (IRC) of citric acid and urea. The GQDs prefer to form an equilibrium shapes of circle with an average particle size ranged from 5 to 10 nm. The N/C atomic ratio in GQDs can be precisely tailored in a range from 21.6 to 49.6 at.% by simply controlling the weight ratio of citric acid to urea. With increasing the urea content, the GQDs not only contain N-doped graphene but also incorporate with crystalline cyanuric acid, forming a binary crystallinity. The quantum yield of 22.2% is achieved by N-doped GQDs, prepared from the IRC synthesis of chemical precursor at the citric acid/urea at 3:1. Excessive N and cyanuric acid can lead to FL quenching, red shift and wide spectral distribution. The design of GQDs possesses a multiple chromophoric band-gap structure, originated from the presence of cyanuric acid, defect-related emissive traps, and functional group distributions. This work offers an effective and inspiring approach to engineering both chemical compositions and unique crystalline structures of GQDs, and will therefore facilitate their fundamental research and applications to optical, sensing, energy and biological fields.

Original languageEnglish
Article number116774
JournalJournal of Luminescence
StatePublished - Jan 2020


  • Fluorescence emission
  • Graphene quantum dots
  • Infrared carbonization
  • Nitrogen doping
  • Thermal pyrolysis


Dive into the research topics of 'Fluorescence of functionalized graphene quantum dots prepared from infrared-assisted pyrolysis of citric acid and urea'. Together they form a unique fingerprint.

Cite this