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

Abstract

AbstractInorganic‐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 nano‐composites, 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.