White-Light Emission from Unmodified Graphene Oxide Quantum Dots

Abstract

We report herein the synthesis and characterization of unmodified graphene oxide quantum dots (GOQDs) with white-light-emitting properties, upon photoexcitation at 340 nm. The Commission International de l'E ćlairage (CIE) 1931 chromaticity coordinates for GOQDs (x = 0.29, y = 0.34) suggest that highly pure white-light emission was achieved. A detailed mechanistic study was carried out utilizing UV−visible absorption, steady-state and time-resolved fluorescence spectroscopy, and dynamic light scattering (DLS) techniques to understand the origin of the white-light emission. The results taken together suggest that GOQDs could self-assemble in solution and thus transform the luminescence behavior. Furthermore, the results indicate that the pH of the medium also plays a crucial role in assisting the aggregation to generate the white-light emission. The concentrationdependent DLS measurements support a cooperative mechanism for the aggregation kinetics in the system. More importantly, the study suggests that white-light emission can be generated from unmodified graphene oxide quantum dots by tuning their nanoscopic aggregation properties.

Rapid and facile synthesis of graphene oxide quantum dots with good linear and nonlinear optical properties

“…Many approaches have been developed to synthesis GQDs such as hydrothermal, electrochemical, chemical or microwave-assisted cutting, nanolithography, nanotomy-assisted exfoliation and ultrasonic shearing [8][9][10]. In these methods, the carbon-based starting materials may involve graphite [15,16], graphene oxide (GO) [6,[17][18][19], carbon nanotubes (CNTs) [20,21] [22] and carbon fibers (CFs) [23] Furthermore, GQDs have been prepared by bottom-up approaches such as pyrolysis, hydrothermal treatment and exfoliation [24]. The preparation of GQDs from GO via Hummers methods is one of the most effective method for synthesizing GQDs [19].…”

Recent Advances in Graphene Quantum Dots as Bioimaging Probes

“…Generally, the approaches can be divided into two groups: top-down and bottom-up methods. In the top-down methods, GQDs are usually synthesized through the cleavage of relatively large bulk precursors, such as graphite [53][54][55], carbon black [56][57][58], coal [59][60][61], metal-organic framework (MOF) [40], 3D graphene [62], graphene oxide (GO) [63][64][65][66][67], carbon nanotubes [68][69][70], carbon fiber [53,[71][72][73] and C 60 [74,75] into small pieces of graphene sheets by chemical oxidation etching [76][77][78][79][80][81], electrochemical exfoliation [65,[82][83][84][85], Li/K intercalation [86,87], hydrothermal/solvothermal treatment [88][89][90][91][92][93][94], microwave irradiation [95...…”

White‐Light‐Emitting Melamine‐Formaldehyde Microspheres through Polymer‐Mediated Aggregation and Encapsulation of Graphene Quantum Dots

“…[6][7][8][9] However, the mining and utilization of REE resources trigger many environmental and economic issues. Various organic or carbon fluorescent materials including carbon quantum dots, [10][11][12][13] organic dyes, [14][15][16][17][18] conjugate polymers, [19,20] and graphene quantum dots (GQDs) [21][22][23][24][25] have been used to develop white-light-emitting materials. Various organic or carbon fluorescent materials including carbon quantum dots, [10][11][12][13] organic dyes, [14][15][16][17][18] conjugate polymers, [19,20] and graphene quantum dots (GQDs) [21][22][23][24][25] have been used to develop white-light-emitting materials.…”

“…[2,4] GQDs are receiving extensive attention because of their superior properties, such as size-tunable emission, high chemical, and optical stability, as well as good biocompatibility. [25,33] Through controlled GQD aggregation in aqueous solution regulated by GQD concentration and solution pH and temperature, Ghosh and Prasad achieved white-light emission using a single kind of unmodified GQDs. [26,31,32] Aggregation of GQDs can result in redshift and broadening of their emission spectra.…”

“…[26][27][28][29][30] Interestingly, the luminescence properties of GQDs can be regulated not only by their size and modifications but also by their assembly state. [25] Compared with materials prepared from multiple fluorophores, the materials obtained by controlled aggregation of a single kind of GQDs have several significant advantages. [25,33] Through controlled GQD aggregation in aqueous solution regulated by GQD concentration and solution pH and temperature, Ghosh and Prasad achieved white-light emission using a single kind of unmodified GQDs.…”