Large-scale simultaneous synthesis of highly photoluminescent green amorphous carbon nanodots and yellow crystalline graphene quantum dots at room temperature

Abstract

The room temperature synthesis of highly PL CNDs and GQDs by simply mixing TETA and p-benzoquinone and the origin of their photoluminescence.

Facile Preparation of Highly Luminescent Nitrogen-Doped Carbonaceous Nanospheres and Potential Application in Intracellular Imaging of Quercetin

“…1b), which matched well with that of the C (100) facet of graphite. [7] This was further confirmed by SAED (Fig. 1c), and indicate that the LNCNs were organised in a partially crystalline manner.…”

“…Carbon-based nanomaterials (CNMs) with a core-shell structure have a nanocrystalline core of sp 2 -hybridised carbon clusters and a functional group formed shell of sp 3 -hybridised carbons. [7][8][9][10] Compared with organic dyes and semiconducting quantum dots, CNMs have a unique combination of many distinct merits, such as high photostability, excellent biocompatibility, low cytotoxicity, especial physicochemical properties, good dispersibility, and chemical inertness. [11][12][13][14] However, pristine CNMs have a high density of defect states, which leads to their low fluorescence efficiency and selectivity.…”

Green synthesis, biomedical and biotechnological applications of carbon and graphene quantum dots. A review

“…Highly photoluminescent carbon dots have been prepared, with a quantum yield of up to 35.3%, at room temperature which can be further separated out into green-emissive amorphous carbon nano-dots and yellow-emissive crystalline graphene quantum dots through a silica gel column. The ensuing carbon dots, even with the same particle-size distribution and chemical groups, have different degrees of surface oxidation (Liu et al 2017b). Additionally, highly fluorescent carbon quantum dots (~ 6 nm) were prepared by the pyrolysis of Eleusine coracana as a carbon source wherein Cu 2+ strongly quenched the fluorescent intensity of carbon quantum dots compared to other metal ions; Cu 2+ preferentially adsorbed on aromatic CC (π-bond) of carbon quantum dots, whereas other divalent metals form σ-bond(s) with the carbon quantum dots (Murugan et al 2019).…”

“…Expectantly, increasing interest in the fabrication of these quantum dots, in view of their straightforward production and their integration with other nanomaterials, is sustainable. Although various processes and starting materials have been researched for their assembly, none or handful of these nanostructures have been able to make into marketable products yet (Liu et al 2017b;Wang et al 2016b;Murugan et al 2019;Halder et al 2018;Chen et al 2019;de Menezes et al 2019;Barras et al 2016;Nekoueian et al 2019;Li et al 2015;Mei et al 2016;Lin et al 2014).…”

“…Photoluminescence is one of the extremely attractive characteristics of carbon and graphene quantum dots, but these properties are highly dependent on the raw materials deployed in fabrication and the presence of surface functionalities on these particles which are noticeable in the case of carbon quantum dots from organic molecules and biomass. Most importantly, one of the lingering challenges has been to improve and develop the quantum yield of carbon quantum dots while taking full advantage of their intrinsic characteristics and to fine-tune their emission spectrum; the improvement in carbon quantum dots with strong fluorescence emission is crucial for biomedical imaging without harmful effects (Liu et al 2017b;Wang et al 2016b;Murugan et al 2019;Halder et al 2018;Chen et al 2019;de Menezes et al 2019;Barras et al 2016;Nekoueian et al 2019;Li et al 2015;Mei et al 2016;Lin et al 2014).…”