Zinc Oxide Sensitized Graphene Quantum Dots “ZnO‐GQDs”: A Hybrid Concept to Study Charge Transfer and its Catalytic Applicability to Synthesize Tetrasubstituted Propargylamines

Abstract

Inorganic-organic hybrid nanostructures of graphene quantum dots (GQDs) have received much intentness in industrial/academic discipline as they may replace traditional quantum semiconductors, due to their superiority in terms of chemical inertness, biocompatibility and low toxicity. In the present work, graphene quantum dots (GQDs) have been synthesized by an inexpensive facile bottom-up approach exhibiting one step pyrolysis of L-glutamic acid. The synthesized GQDs found to have an excitation wavelength dependence of the emission wavelength. The effect on optical and structural properties of GQDs are then studied by varying the synthesis reaction time. The morphological alterations in GQDs were observed when the reaction time increases i. e. spherical to sheet like which may be attributed to interconnecting graphene quantum dots (GQDs), which are termed as 'GQD sheets.' The synthesized GQDs are further coupled with zinc oxide (ZnO) to form ZnO : GQDs nanocomposites, which shows an effective interfacial charge transfer from ZnO to GQDs leading to an enhancement in the photo absorption of ZnO from UV to visible region. The coupled ZnO : GQDs nano-composites were then explored for the catalytic applicability to synthesize tetrasubstituted propargylamines via KA2 mechanism showing closeness to ideal green chemistry metrics.

"Off/On” Fluorescent Probe based on Aggregation-Induced Quenching of ZnO-Quantum dots for Determination of Ara-C: Pharmacokinetic Applications, Adsorption Kinetics & Green Profile Assessment

“…The vibration band assigned for ZnO is located at 533 cm −1 . These FT-IR observations confirmed the successful synthesis of ZnO-QDs and well-matched with the previous reported studies [ 39 ].…”

Nature of photoexcited states in ZnO-embedded graphene quantum dots

“…49 One more important application of ZnO-GQDs hybrid nanomaterials is related to their excellent photocatalytic properties. The enhanced light absorption in such combined systems and, consequently, increased number of photo-induced charge carriers make it possible to reach synthesis of tetrasubstituted propargylamines, 50 improved solar-driven water splitting 51 and photocatalytic H 2 evolution under visible light, 52 selective reduction of nitroarenes, 53 and effective degradation of metronidazole (MNZ) antibiotic, 54 colored pollutants (Rhodamine B, methylene blue (MB) and methylene orange (MO)), [55][56][57][58][59][60][61] colorless pollutant (carbendazim (CZ) fungicide) 62 and glyphosate herbicide contaminated in agricultural wastewater. 63 Effective interfacial charge transfer between GQDs and ZnO under photoirradiation also facilitates the production of reactive oxygen species (ROS), which make it possible to use this material as an antibacterial agent.…”