Abstract
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.
Similar content being viewed by others
References
Geim AK, Novoselov KS (2007) The rise of graphene. Nat Mater 6:183–191. doi:10.1038/nmat1849
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
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
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
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
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
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
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
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
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
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
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
Ye R, Xiang C, Lin J et al (2013) Coal as an abundant source of graphene quantum dots. Nat Commun. doi:10.1038/ncomms3943
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
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
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
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
Baker SN, Baker GA (2010) Luminescent carbon Nanodots: emergent nanolights. Angew Chem Int Ed 49:6726–6744. doi:10.1002/anie.200906623
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
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
Yoo JM, Kang JH, Hong BH (2015) Graphene-based nanomaterials for versatile imaging studies. Chem Soc Rev 44:4835–4852. doi:10.1039/C5CS00072F
Dong Y, Cai J, You X, Chi Y (2015) Sensing applications of luminescent carbon based dots. Analyst 140:7468–7486. doi:10.1039/C5AN01487E
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
Bacon M, Bradley SJ, Nann T (2014) Graphene quantum dots. Part Part Syst Charact 31:415–428. doi:10.1002/ppsc.201300252
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
Haubner K, Murawski J, Olk P et al (2010) The route to functional graphene oxide. ChemPhysChem 11:2131–2139. doi:10.1002/cphc.201000132
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
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
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
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
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
Theoretical Investigations of Optical Origins of Fluorescent Graphene Quantum Dots: Scientific Reports. http://www.nature.com/articles/srep24850. Accessed 4 Dec 2016
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
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
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
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
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
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
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
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
Acknowledgment
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
Authors and Affiliations
Corresponding author
Ethics declarations
The author(s) declare that they have no competing interests.
Electronic supplementary material
ESM 1
(DOCX 1883 kb)
Rights and permissions
About this article
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
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00604-017-2075-9