Controlled Synthesis Of Graphene Quantum Dots

Precisely controlled graphene quantum dots could be used as fluorescent probes for metal ions, scientists say.

AsianScientist (Apr. 21, 2015) – Researchers at Xinjiang Technical Institute of Physics & Chemistry (XTIPC) of the Chinese Academy of Sciences, have developed a top-down approach to synthesize a high-yield preparation of graphene quantum dots (GQDs). Their results have been published in the journal Carbon.

GQDs combine the excellent properties of graphene with quantum mechanical properties of quantum dots. However, scientists have struggled to synthesize GQDs with uniform particle size and strong dispersity.

In the present study, a high-yield (48 percent) preparation and a facile separation of yellow-luminescent GQDs have been synthesized by using a pre-made carbon replica (C/SBA-15) of SBA-15 as a nanoreactor. The GQDs were then cut from the template using HNO3 vapor and the templates were re-used.

Researchers found that the C/SBA-15 template could be used as a nanoreactor for the preparation of GQDs with controllable sizes due to its confined mesoporous structure and filling graphitic carbons. They obtained GQDs containing abundant oxygen-containing groups that showed a narrow size distribution (2.5-5.2 nm), good water solubility, good photostability and high selectivity for Fe(III) sensing.

The researchers also investigated the use of their GQDs as fluorescent probes for Fe(III) determination in tap water. Their results showed that the GQDs exhibited a high selectivity towards Fe(III), with satisfying recoveries ranging from 94.3 percent to 106 percent.

Other than Fe(III), the experimental data indicated that Cu(II), Co(II), Mn(II), Ni(II) could also quench the fluorescence of the GQDs, suggesting that the GQDs could be used as probes for other metal ions.

This article can be found at: Xu et al. (2015) Nanoreactor-confined Synthesis And Separation Of Yellow-luminescent Graphene Quantum Dots With A Recyclable SBA-15 Template And Their Application For Fe(III) Sensing.

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Source: Chinese Academy of Sciences.
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