Graphene Quantum Dot–Aerogel: From Nanoscopic to Macroscopic Fluorescent Materials. Sensing Polyaromatic Compounds in Water

Abstract

Fluorescence based on quantum confinement is a property restricted to the nanoscopic range. The incorporation of nanoparticles in a three-dimensional polymeric network could afford macroscopic scaffolds that show nanoscopic properties. Moreover, if these scaffolds are based on strong bonds, the stability of the resulting materials can be preserved, thus enhancing their final applications. We report for the first time the preparation of a graphene quantum dot (GQD) composite based on a cationic covalent network. This new material has unusual features: (i) the final composite remains stable after several swelling-deswelling cycles, thus demonstrating strong interactions between GQDs and the polymeric material, and therefore it could be used as a portable system. (ii) Fluorescence emission in the composite and in solution is quasi-independent to the excitation wavelength. (iii) However, and in contrast to the behavior observed in GQD solutions, the fluorescence of the composite remains unaltered over a wide pH range and in the presence of different ions commonly found in tap water. (iv) Fluorescence quenching is only observed as a consequence of molecules that bear aromatic systems, and this could be applied to the preparation of in situ water sensors.

A Practical Guide to Prepare and Synthetically Modify Graphene Quantum Dots

“…Although secondary interactions inherently provide weaker binding, ionic, hydrogen bonding, π–π, van der Waals, and metal–ion interactions have all been utilized in recent times to coat the GQD exterior for cellular imaging,[1c] drug delivery, sensing, and gel formation applications. [40b,111]…”

Versatile Aerogels for Sensors

“…Moreover, the recovery of Cd 2+ , Pb 2+ , Cu 2+ , and Hg 2+ was between 86.7–104.7%. Another approach proposed in the literature for detecting heavy metal ions was the introduction of fluorescent materials, of which the fluorescence peak shift and fluorescence quenching happen when addition of metal ions . The carbon dot/aerogel derived from the thenoyltrifluoroacetone prepared by Jelinek and co‐workers showed a comparable selectivity and sensitivity for the fluorescent detection of UO 2 2+ , Sm 3+ , and Eu 3+ ions, and the powdered carbon dot/aerogel was stable and could be kept for a long time .…”

“…The carbon dot/aerogel derived from the thenoyltrifluoroacetone prepared by Jelinek and co‐workers showed a comparable selectivity and sensitivity for the fluorescent detection of UO 2 2+ , Sm 3+ , and Eu 3+ ions, and the powdered carbon dot/aerogel was stable and could be kept for a long time . Recently, the GQDs was introduced into the cationic network to get GQD‐based aerogel, which can be used for detecting polyaromatic molecules in the presence of different ions in water and can be applied in a wide pH range, however, the sensitivity and selectivity should be further improved . The aerogel‐based materials are also employed for SERS detection of dye with relatively low detection limit, however, the signal processing of SERS detection was complicated, and the quantitative analysis was not easy …”

“…Another approach proposed in the literature for detecting heavy metal ions was the introduction of fluorescent materials, of which the fluorescence peak shift and fluorescence quenching happen when addition of metal ions. [302,303] The carbon dot/aerogel derived from the thenoyltrifluoroacetone prepared by Jelinek and co-workers showed a comparable selectivity and sensitivity for the fluorescent detection of UO 2 2+ , Sm 3+ , and Eu 3+ ions, and the powdered carbon dot/aerogel was stable and could be kept for a long time. [302] Recently, the GQDs was introduced into the cationic network to get GQD-based aerogel, which can be used for detecting polyaromatic molecules in the presence of different ions in water and can be applied in a wide pH range, however, the sensitivity and selectivity should be further improved.…”

“…[302] Recently, the GQDs was introduced into the cationic network to get GQD-based aerogel, which can be used for detecting polyaromatic molecules in the presence of different ions in water and can be applied in a wide pH range, however, the sensitivity and selectivity should be further improved. [303] The aerogel-based materials are also employed for SERS detection of dye with relatively low detection limit, however, the signal processing of SERS detection was complicated, and the quantitative analysis was not easy. [304,305] As for explosives detection, Su and co-workers [306] studied the gelation condition for the trivalent metal ions and the fluorescent ligand, and finally got luminescent metal-organic gels.…”