Heterogeneity in the fluorescence of graphene and graphene oxide quantum dots


Heterogeneity is an inherent property of a wealth of real-world nanomaterials and yet rarely in the reporting of new properties is its effect sufficiently addressed. Graphene quantum dots (GQDs) – fluorescent, nanoscale fragments of graphene - are an extreme example of a heterogeneous nanomaterial. Here, top-down approaches – by far the most predominant – produce batches of particles with a distribution of sizes, shapes, extent of oxidation, chemical impurities and more. This makes characterization of these materials using bulk techniques particularly complex and comparisons of properties across different synthetic methods uninformative. In particular, it hinders the understanding of the structural origin of their fluorescence properties. We present a simple synthetic method, which produces graphene quantum dots with very low oxygen content that can be suspended in organic solvents, suggesting a very pristine material. We use this material to illustrate the limitations of interpreting complex data sets generated by heterogeneous materials and we highlight how misleading this “pristine” interpretation is by comparison with graphene oxide quantum dots synthesized using an established protocol. In addition, we report on the solvatochromic properties of these particles, discuss common characterization techniques and their limitations in attributing properties to heterogeneous materials.

Graphene quantum dots with very low oxygen content were synthesized using a simple method, suggesting a very pristine material. We highlight how misleading this “pristine” term is when applied to a heterogeneous material through comparison with graphene oxide quantum dots.

This is a preview of subscription content, access via your institution.

Fig. 1
Fig. 2
Fig. 3
Fig. 4


  1. 1.

    Geim AK, Novoselov KS (2007) The rise of graphene. Nat Mater 6:183–191. doi:10.1038/nmat1849

    CAS  Article  Google Scholar 

  2. 2.

    Shen J, Zhu Y, Yang X, Li C (2012) Graphene quantum dots : emergent nanolights for bioimaging, sensors, catalysis and photovoltaic devices. Chem Commun 48:3686–3699. doi:10.1039/C2CC00110A

    CAS  Article  Google Scholar 

  3. 3.

    Zhuo S, Shao M, Lee S-T (2012) Upconversion and Downconversion fluorescent graphene quantum dots: ultrasonic preparation and Photocatalysis. ACS Nano 6:1059–1064. doi:10.1021/nn2040395

    CAS  Article  Google Scholar 

  4. 4.

    Konstantatos G, Badioli M, Gaudreau L et al (2012) Hybrid graphene-quantum dot phototransistors with ultrahigh gain. Nat Nanotechnol 7:363–368. doi:10.1038/nnano.2012.60

    CAS  Article  Google Scholar 

  5. 5.

    Li Q, Zhang S, Dai L, Li L (2012) Nitrogen-doped colloidal graphene quantum dots and their size-dependent Electrocatalytic activity for the oxygen reduction reaction. J Am Chem Soc 134:18932–18935. doi:10.1021/ja309270h

    CAS  Article  Google Scholar 

  6. 6.

    Liu F, Jang M-H, Ha HD, et al. (2013) Facile synthetic method for pristine graphene quantum dots and graphene oxide quantum dots: origin of blue and green luminescence. Adv Mater n/a–n/a. doi: 10.1002/adma.201300233

  7. 7.

    Jin H, Huang H, He Y et al (2015) Graphene quantum dots supported by graphene Nanoribbons with ultrahigh Electrocatalytic performance for oxygen reduction. J Am Chem Soc 137:7588–7591. doi:10.1021/jacs.5b03799

    CAS  Article  Google Scholar 

  8. 8.

    Mondal S, Rana U, Malik S (2015) Graphene quantum dot-doped polyaniline nanofiber as high performance supercapacitor electrode materials. Chem Commun 51:12365–12368. doi:10.1039/C5CC03981A

    CAS  Article  Google Scholar 

  9. 9.

    Son DI, Kwon BW, Park DH et al (2012) Emissive ZnO-graphene quantum dots for white-light-emitting diodes. Nat Nanotechnol 7:465–471. doi:10.1038/nnano.2012.71

    CAS  Article  Google Scholar 

  10. 10.

    Ponomarenko LA, Schedin F, Katsnelson MI et al (2008) Chaotic Dirac billiard in graphene quantum dots. Science 320:356–358. doi:10.1126/science.1154663

    CAS  Article  Google Scholar 

  11. 11.

    Dong Y, Chen C, Zheng X et al (2012) One-step and high yield simultaneous preparation of single- and multi-layer graphene quantum dots from CX-72 carbon black. J Mater Chem 22:8764–8766. doi:10.1039/C2JM30658A

    CAS  Article  Google Scholar 

  12. 12.

    Peng J, Gao W, Gupta BK et al (2012) Graphene quantum dots derived from carbon fibers. Nano Lett 12:844–849. doi:10.1021/nl2038979

    CAS  Article  Google Scholar 

  13. 13.

    Ye R, Xiang C, Lin J et al (2013) Coal as an abundant source of graphene quantum dots. Nat Commun. doi:10.1038/ncomms3943

    Google Scholar 

  14. 14.

    Shin Y, Lee J, Yang J et al (2014) Mass production of graphene quantum dots by one-pot synthesis directly from graphite in high yield. Small 10:866–870. doi:10.1002/smll.201302286

    CAS  Article  Google Scholar 

  15. 15.

    Liu W-W, Feng Y-Q, Yan X-B et al (2013) Superior micro-supercapacitors based on graphene quantum dots. Adv Funct Mater 23:4111–4122. doi:10.1002/adfm.201203771

    CAS  Article  Google Scholar 

  16. 16.

    Song SH, Jang M-H, Chung J et al (2014) Highly efficient light-emitting diode of graphene quantum dots fabricated from graphite intercalation compounds. Adv Opt Mater 2:1016–1023. doi:10.1002/adom.201400184

    CAS  Article  Google Scholar 

  17. 17.

    Yeh T-F, Teng C-Y, Chen S-J, Teng H (2014) Nitrogen-doped graphene oxide quantum dots as photocatalysts for overall water-splitting under visible light illumination. Adv Mater 26:3297–3303. doi:10.1002/adma.201305299

    CAS  Article  Google Scholar 

  18. 18.

    Baker SN, Baker GA (2010) Luminescent carbon Nanodots: emergent nanolights. Angew Chem Int Ed 49:6726–6744. doi:10.1002/anie.200906623

    CAS  Article  Google Scholar 

  19. 19.

    Liu Q, Guo B, Rao Z et al (2013) Strong two-photon-induced fluorescence from Photostable, biocompatible nitrogen-doped graphene quantum dots for cellular and deep-tissue imaging. Nano Lett 13:2436–2441. doi:10.1021/nl400368v

    CAS  Article  Google Scholar 

  20. 20.

    Ge J, Lan M, Zhou B et al (2014) A graphene quantum dot photodynamic therapy agent with high singlet oxygen generation. Nat Commun. doi:10.1038/ncomms5596

    Google Scholar 

  21. 21.

    Yoo JM, Kang JH, Hong BH (2015) Graphene-based nanomaterials for versatile imaging studies. Chem Soc Rev 44:4835–4852. doi:10.1039/C5CS00072F

    CAS  Article  Google Scholar 

  22. 22.

    Dong Y, Cai J, You X, Chi Y (2015) Sensing applications of luminescent carbon based dots. Analyst 140:7468–7486. doi:10.1039/C5AN01487E

    CAS  Article  Google Scholar 

  23. 23.

    Schroeder KL, Goreham RV, Nann T (2016) Graphene quantum dots for Theranostics and bioimaging. Pharm Res 33:2337–2357. doi:10.1007/s11095-016-1937-x

    CAS  Article  Google Scholar 

  24. 24.

    Bacon M, Bradley SJ, Nann T (2014) Graphene quantum dots. Part Part Syst Charact 31:415–428. doi:10.1002/ppsc.201300252

  25. 25.

    Sk MA, Ananthanarayanan A, Huang L et al (2014) Revealing the tunable photoluminescence properties of graphene quantum dots. J Mater Chem C 2:6954–6960. doi:10.1039/C4TC01191K

    CAS  Article  Google Scholar 

  26. 26.

    Zheng XT, Ananthanarayanan A, Luo KQ, Chen P (2015) Glowing graphene quantum dots and carbon dots: properties, syntheses, and biological applications. Small 11:1620–1636. doi:10.1002/smll.201402648

    CAS  Article  Google Scholar 

  27. 27.

    Yan X, Cui X, Li B, Li L (2010) Large, solution-Processable graphene quantum dots as light absorbers for Photovoltaics. Nano Lett 10:1869–1873. doi:10.1021/nl101060h

    CAS  Article  Google Scholar 

  28. 28.

    Yan X, Cui X, Li L (2010) Synthesis of large, stable colloidal graphene quantum dots with tunable size. J Am Chem Soc 132:5944–5945. doi:10.1021/ja1009376

    CAS  Article  Google Scholar 

  29. 29.

    Kim S, Hwang SW, Kim M-K et al (2012) Anomalous behaviors of visible luminescence from graphene quantum dots: interplay between size and shape. ACS Nano 6:8203–8208. doi:10.1021/nn302878r

    CAS  Article  Google Scholar 

  30. 30.

    Wang L, Wang Y, Xu T et al (2014) Gram-scale synthesis of single-crystalline graphene quantum dots with superior optical properties. Nat Commun. doi:10.1038/ncomms6357

    Google Scholar 

  31. 31.

    Ryu S, Lee K, Hong SH, Lee H (2014) Facile method to sort graphene quantum dots by size through ammonium sulfate addition. RSC Adv 4:56848–56852. doi:10.1039/C4RA07032A

    CAS  Article  Google Scholar 

  32. 32.

    Röding M, Bradley SJ, Nydén M, Nann T (2014) Fluorescence lifetime analysis of graphene quantum dots. J Phys Chem C 118:30282–30290. doi:10.1021/jp510436r

    Article  Google Scholar 

  33. 33.

    Mohanty N, Moore D, Xu Z et al (2012) Nanotomy-based production of transferable and dispersible graphene nanostructures of controlled shape and size. Nat Commun 3:844. doi:10.1038/ncomms1834

    Article  Google Scholar 

  34. 34.

    Lu J, Yeo PSE, Gan CK et al (2011) Transforming C60 molecules into graphene quantum dots. Nat Nanotechnol 6:247–252. doi:10.1038/nnano.2011.30

    CAS  Article  Google Scholar 

  35. 35.

    Fuyuno N, Kozawa D, Miyauchi Y et al (2014) Drastic change in photoluminescence properties of graphene quantum dots by chromatographic separation. Adv Opt Mater 2:983–989. doi:10.1002/adom.201400200

    CAS  Article  Google Scholar 

  36. 36.

    Ruoff RS, Tse DS, Malhotra R, Lorents DC (1993) Solubility of fullerene (C60) in a variety of solvents. J Phys Chem 97:3379–3383. doi:10.1021/j100115a049

    CAS  Article  Google Scholar 

  37. 37.

    Coleman JN, Lotya M, O’Neill A et al (2011) Two-dimensional Nanosheets produced by liquid exfoliation of layered materials. Science 331:568–571. doi:10.1126/science.1194975

    CAS  Article  Google Scholar 

  38. 38.

    Hernandez Y, Nicolosi V, Lotya M et al (2008) High-yield production of graphene by liquid-phase exfoliation of graphite. Nat Nanotechnol 3:563–568. doi:10.1038/nnano.2008.215

    CAS  Article  Google Scholar 

  39. 39.

    Wang S, Zhang Y, Abidi N, Cabrales L (2009) Wettability and surface free energy of graphene films. Langmuir 25:11078–11081. doi:10.1021/la901402f

    CAS  Article  Google Scholar 

  40. 40.

    Ha HD, Jang M-H, Liu F et al (2015) Upconversion photoluminescent metal ion sensors via two photon absorption in graphene oxide quantum dots. Carbon 81:367–375. doi:10.1016/j.carbon.2014.09.069

    CAS  Article  Google Scholar 

  41. 41.

    Novoselov KS, Geim AK, Morozov SV et al (2004) Electric field effect in atomically thin carbon films. Science 306:666–669. doi:10.1126/science.1102896

    CAS  Article  Google Scholar 

  42. 42.

    Kobayashi Y, Fukui K, Enoki T et al (2005) Observation of zigzag and armchair edges of graphite using scanning tunneling microscopy and spectroscopy. Phys Rev B 71:193406. doi:10.1103/PhysRevB.71.193406

    Article  Google Scholar 

  43. 43.

    Haubner K, Murawski J, Olk P et al (2010) The route to functional graphene oxide. ChemPhysChem 11:2131–2139. doi:10.1002/cphc.201000132

    CAS  Article  Google Scholar 

  44. 44.

    Li Y, Liu H, Liu X et al (2016) Free-radical-assisted rapid synthesis of graphene quantum dots and their Oxidizability studies. Langmuir 32:8641–8649. doi:10.1021/acs.langmuir.6b02422

    CAS  Article  Google Scholar 

  45. 45.

    Chua CK, Sofer Z, Šimek P et al (2015) Synthesis of strongly fluorescent graphene quantum dots by cage-opening buckminsterfullerene. ACS Nano 9:2548–2555. doi:10.1021/nn505639q

    CAS  Article  Google Scholar 

  46. 46.

    Kim S, Shin DH, Kim CO et al (2013) Size-dependence of Raman scattering from graphene quantum dots: interplay between shape and thickness. Appl Phys Lett 102:053108. doi:10.1063/1.4790641

    Article  Google Scholar 

  47. 47.

    Reigue A, Auguié B, Etchegoin PG, Le Ru EC (2013) CW measurements of resonance Raman profiles, line-widths, and cross-sections of fluorescent dyes: application to Nile blue a in water and ethanol. J Raman Spectrosc 44:573–581. doi:10.1002/jrs.4233

    CAS  Article  Google Scholar 

  48. 48.

    Resch-Genger U, Grabolle M, Cavaliere-Jaricot S et al (2008) Quantum dots versus organic dyes as fluorescent labels. Nat Methods 5:763–775. doi:10.1038/nmeth.1248

    CAS  Article  Google Scholar 

  49. 49.

    Theoretical Investigations of Optical Origins of Fluorescent Graphene Quantum Dots: Scientific Reports. http://www.nature.com/articles/srep24850. Accessed 4 Dec 2016

  50. 50.

    Jin SH, Kim DH, Jun GH et al (2013) Tuning the photoluminescence of graphene quantum dots through the charge transfer effect of functional groups. ACS Nano 7:1239–1245. doi:10.1021/nn304675g

    CAS  Article  Google Scholar 

  51. 51.

    Kochmann S, Hirsch T, Wolfbeis OS (2012) The pH dependence of the Total fluorescence of graphite oxide. J Fluoresc 22:849–855. doi:10.1007/s10895-011-1019-8

    CAS  Article  Google Scholar 

  52. 52.

    Chen W, Li F, Wu C, Guo T (2014) Optical properties of fluorescent zigzag graphene quantum dots derived from multi-walled carbon nanotubes. Appl Phys Lett 104:063109. doi:10.1063/1.4863963

    Article  Google Scholar 

  53. 53.

    Li C, Yue Y (2014) Fluorescence spectroscopy of graphene quantum dots: temperature effect at different excitation wavelengths. Nanotechnology 25:435703. doi:10.1088/0957-4484/25/43/435703

    Article  Google Scholar 

  54. 54.

    Li L-L, Ji J, Fei R et al (2012) A facile microwave avenue to Electrochemiluminescent two-color graphene quantum dots. Adv Funct Mater 22:2971–2979. doi:10.1002/adfm.201200166

    CAS  Article  Google Scholar 

  55. 55.

    Li Y, Hu Y, Zhao Y et al (2011) An electrochemical avenue to green-luminescent graphene quantum dots as potential electron-acceptors for Photovoltaics. Adv Mater 23:776–780. doi:10.1002/adma.201003819

    Article  Google Scholar 

  56. 56.

    Tang L, Ji R, Cao X et al (2012) Deep ultraviolet photoluminescence of water-soluble self-Passivated graphene quantum dots. ACS Nano 6:5102–5110. doi:10.1021/nn300760g

    CAS  Article  Google Scholar 

  57. 57.

    Riesen H, Wiebeler C, Schumacher S (2014) Optical spectroscopy of graphene quantum dots: the case of C132. J Phys Chem A 118:5189–5195. doi:10.1021/jp502753a

    CAS  Article  Google Scholar 

Download references


We would like to acknowledge the work of Anne Wendel, Marek Josianiak and Chris Bassel, who helped us with the XPS measurements as well as the VUW Raman group – specifically Baptiste Auguié and Eric Le Ru for contributing their Raman expertise.

Author contributions

The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.

Author information



Corresponding author

Correspondence to Thomas Nann.

Ethics declarations

The author(s) declare that they have no competing interests.

Electronic supplementary material


(DOCX 1883 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Bradley, S.J., Kroon, R., Laufersky, G. et al. Heterogeneity in the fluorescence of graphene and graphene oxide quantum dots. Microchim Acta 184, 871–878 (2017). https://doi.org/10.1007/s00604-017-2075-9

Download citation


  • Graphene quantum dots
  • Quantum yield
  • Fluorescence lifetime
  • Photoluminescence
  • Characterization
  • TEM
  • NMR
  • Raman spectroscopy