Functionalized graphene transistor for ultrasensitive detection of carbon quantum dots

Jana Brndiarova, Peter Siffalovic, Martin Hulman, Anna Kalosi, Michal Bodik, Viera Skakalova, Matej Micusik, Zoran Markovic, Eva Majkova, Karol Frohlich

Ubiquitous carbon nanomaterials have great potential for emerging technologies, but they also pose a threat to human health at the end of their lifecycle, especially when they are introduced into waste or ground waters. Graphene field-effect transistors (GFET) and real time in situ confocal Raman microscopy (CRM) were employed to detect a submonolayer of carbon quantum dots (CQDs) in water. An effective GFET channel was formed on exfoliated and chemical vapor deposited (CVD) graphene. The adsorption of CQDs was monitored by measuring conductance changes in GFETs. The graphene channel was functionalized with (3-aminopropyl) triethoxysilane (APTES), which allowed for easy observation of a shift in the charge neutrality point (CNP) when the graphene channel was exposed to CQDs. The affinity of the CQD's carboxyl terminal groups to the aminofunctionalized channel enabled a highly sensitive CQD detection based on changes in the GFET conductivity. The adsorption of the CQDs induced a positive shift of the CNP with a limit of detection at concentrations of 239 ppm and 62 ppm for the exfoliated and CVD graphene, respectively. A supporting study of graphene functionalization and CQD adsorption was performed by real time in situ CRM, ellipsometry, and ex situ X-ray photoelectron spectroscopy.

Physics of Nanostructured Materials
External organisation(s)
Slovak Academy of Sciences (SAS), Danubia NanoTech, University of Belgrade
Journal of Applied Physics
No. of pages
Publication date
Peer reviewed
Austrian Fields of Science 2012
103018 Materials physics
ASJC Scopus subject areas
Physics and Astronomy(all)
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