Blue and green photoluminescence graphene quantum dots synthesized from carbon fibers

Xie, Minmin; Su, Yanjie; Lu, Xiaonan; Zhang, Yaozhong; Liu, Yang; Zhang, Yafei

doi:10.1016/j.matlet.2012.11.029

Cited by 67 publications

(27 citation statements)

References 20 publications

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“…Electron transition between discrete energy level in GQDs leads to PL. 6 Previous studies have shown that doping of hetero-atoms into the GQDs is an effective way to alter the band gap or introduce new energy levels into the GQDs which can be used to tune the PL properties in order to make GQDs suitable for various applications. 7 Up to date, research efforts have been mainly focused on doping non-metallic atoms like nitrogen, 8 sulphur, 7,9 chlorine, 10 fluorine 11 and selenium 12 into GQDs.…”

Section: Introductionmentioning

confidence: 99%

Potassium doping: Tuning the optical properties of graphene quantum dots

Qian

Tang

et al. 2016

AIP Advances

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Doping with hetero-atoms is an effective way to tune the properties of graphene quantum dots (GQDs). Here, potassium-doped GQDs (K-GQDs) are synthesized by a one-pot hydrothermal treatment of sucrose and potassium hydroxide solution. Optical properties of the GQDs are altered as a result of K-doping. The absorption peaks exhibit a blue shift. Multiple photoluminescence (PL) peaks are observed as the excitation wavelength is varied from 380 nm to 620 nm. New energy levels are introduced into the K-GQDs and provide alternative electron transition pathways. The maximum PL intensity of the K-GQDs is obtained at an excitation wavelength of 480 nm which is distinct from the undoped GQDs (375 nm). The strong PL of the K-GQDs at the longer emission wavelengths is expected to make K-GQDs more suitable for bioimaging and optoelectronic applications.

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Section: Introductionmentioning

confidence: 99%

Potassium doping: Tuning the optical properties of graphene quantum dots

Qian

Tang

et al. 2016

AIP Advances

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“…9 Carbon dots have also been synthesized from CFs by electrochemical etching; 22 other reports of CF-derived CNPs use single-temperature and reaction-time conditions. 10 Although there is a plethora of literature on various reaction conditions at different temperatures and oxidizing conditions using nitric acid only, 3 nitric acidsulfuric acid mixtures, 4 and modified Hummers' methods, 5 there is a distinct lack of fundamental studies and understanding of the reaction dynamics and the species produced at various time points. Furthermore, a detailed study of intact CFs treated under a mixture of nitric and sulfuric acids has previously revealed that oxygen-, nitrogen-, and sulfur-containing groups varied discontinuously over time on the CF surface, especially in the early stages of reaction.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic Characteristics of Carbon Dots (C-Dots) Derived from Carbon Fibers and Conversion to Sulfur-Bridged C-Dots Nanosheets

et al. 2015

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We synthesized sub-10 nm carbon nanoparticles (CNPs) consistent with photoluminescent carbon dots (C-dots) from carbon fiber starting material. The production of different C-dots fractions was monitored over seven days. During the course of the reaction, one fraction of C-dots species with relatively high photoluminescence was short-lived, emerging during the first hour of reaction but disappearing after one day of reaction. Isolation of this species during the first hour of the reaction was crucial to obtaining higherluminescent C-dots species. When the reaction proceeded for one week, the appearance of larger nanostructures was observed over time, with lateral dimensions approaching 200 nm. The experimental evidence suggests that these larger species are formed from small C-dot nanoparticles bridged together by sulfur-based moieties between the C-dot edge groups, as if the C-dots polymerized by cross-linking the edge groups through sulfur bridges. Their size can be tailored by controlling the reaction time. Our results highlight the variety of CNP products, from sub-10 nm C-dots to $200 nm sulfur-containing carbon nanostructures, that can be produced over time during the oxidation reaction of the graphenic starting material. Our work provides a clear understanding of when to stop the oxidation reaction during the top-down production of Cdots to obtain highly photoluminescent species or a target average particle size.

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“…4,5 To fabricate graphene quantum dots, there are two main ways, namely the top-down and bottom-up approaches. The topdown method consists in breaking carbonaceous materials such as graphene sheets, graphene oxide or graphite to GQDs/ GOQDs, through chemical oxidation and exfoliation, 6 hydrothermal synthesis, 7 electrochemical synthesis, 8 UV-assisted synthesis 9 and microwaves. 10 Top-down methods can not control the shape and the size of quantum dots.…”

Section: Introductionmentioning

confidence: 99%