scholarly journals Tunable optical properties of OH-functionalised graphene quantum dots

2016 ◽  
Vol 4 (36) ◽  
pp. 8429-8438 ◽  
Author(s):  
K. R. Geethalakshmi ◽  
Teng Yong Ng ◽  
Rachel Crespo-Otero
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Graphene Oxide ◽  
Graphene Quantum Dots ◽  
Photoluminescence Properties ◽  
Electron Hole ◽  
Oh Groups ◽  
Optical Gap ◽  
Tunable Optical Properties ◽  
Graphene Oxide Quantum Dots

Functionalisation with OH groups can tune the optical properties of Graphene oxide quantum dots (GO-QDs). Selective functionalisation of positions with large electron–hole separation offers a strategy to control the optical gap and photoluminescence properties.

The Role of Reduced Graphene Oxide Concentration as Ablated Material on Optical Properties of Graphene Quantum Dots

2019 ◽  
Vol 948 ◽  
pp. 267-273 ◽  
Author(s):  
Fiqhri Heda Murdaka ◽  
Ahmad Kusumaatmaja ◽  
Isnaeni ◽  
Iman Santoso
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Graphene Oxide ◽  
Band Gap ◽  
Reduced Graphene Oxide ◽  
Optical Band Gap ◽  
Graphene Quantum Dots ◽  
Absorption Peak ◽  
Oxygen Defect ◽  
Reduced Graphene

We report the synthesize of Graphene Quantum Dots (GQDs) using ablation method with reduced Graphene Oxide (rGO) solution as a starting material. We have varied the concentration of rGO as following: 0.5, 2, 5 mg/ml and then have ablated them using 800 nm Ti-Sapphire femtosecond laser to obtain GQDs. From the UV-Vis data, we observed that the more concentration of rGO is being ablated, the more secondary absorption peak at 255.1 nm appeared. This secondary absorption peak is a characteristic of n-π* bonding due to the presence of oxygen defect which occurs as a result of the interaction between the laser and the water in rGO solution. We conclude that the population of oxigen defect in GQDs is increasing, following the increase of rGO concentration and could alter the optical properties of GQD. On the other hand, using Tauc’s plot, we confirm that the increase of rGO concentration as the ablated material does not alter GQDs optical band gap. However, it will slightly reduce both, direct and indirect Oxygen defect related optical band gap.

scholarly journals Transforming Carbon Black into Graphene Oxide Quantum Dots by Pulsed Laser Ablation in Ethanol

2020 ◽  
Vol 58 (11) ◽  
pp. 808-814
Author(s):  
Jung-Il Lee ◽  
Jeong Ho Ryu
Keyword(s):  
Quantum Dots ◽  
Graphene Oxide ◽  
Laser Ablation ◽  
Carbon Black ◽  
Graphene Quantum Dots ◽  
Pulsed Laser ◽  
Blue Emission ◽  
Pulsed Laser Ablation ◽  
Absorption Bands ◽  
Graphene Oxide Quantum Dots

Graphene oxide quantum dots (GOQDs) are nanometer-sized graphene oxide fragments that exhibit unique properties, making them interesting candidates for a range of new applications. Carbon black, one of the commercially available carbon precursors, is produced by the thermal decomposition or incomplete combustion of organic compounds. It is commonly used as a supporting material for catalysts because of its excellent electrical conductivity, high surface area, and stability. In this paper, we report the transformation of carbon black into GOQDs in 10 min using a one-step facile approach. This transformation was achieved by pulsed laser ablation (PLA) in ethanol using the earth-abundant and low-cost carbon black as precursor. Only ethanol and carbon black were used for the transformation. The carbon clusters ablated from the carbon black were completely transformed into GOQDs with a homogeneous size distribution and heights in the range of 0.3-1.7 nm. This confirmed that the transformed GOQDs consisted of only single- or few-layered graphene quantum dots. The UV-vis spectra showed absorption bands at 215, 260, and 320 nm, which were attributed to the π→π* transition of the C=C of the sp<sup>2</sup> C bond in the sp<sup>3</sup> C matrix. A distinct blue emission peak at 450 nm was evident at an excitation wavelength of 360 nm. The broader PL emission spectra are due to the oxygen-related functional groups emitting PL between 300 and 440 nm.

Graphene quantum dots from fishbone carbon nanofibers

RSC Advances ◽  
2016 ◽  
Vol 6 (54) ◽  
pp. 48504-48514 ◽  
Author(s):  
D. Torres ◽  
J. L. Pinilla ◽  
E. M. Gálvez ◽  
I. Suelves
Keyword(s):  
Quantum Dots ◽  
Graphene Oxide ◽  
Carbon Nanofibers ◽  
Graphene Quantum Dots ◽  
Differential Centrifugation ◽  
Graphene Oxide Quantum Dots

Photoluminescent graphene oxide quantum dots (GOQD) obtained from chemically oxidized fishbone carbon nanofibers (CNF) and separated by degressive differential centrifugation.

Facile Synthetic Method for Pristine Graphene Quantum Dots and Graphene Oxide Quantum Dots: Origin of Blue and Green Luminescence

2013 ◽  
Vol 25 (27) ◽  
pp. 3657-3662 ◽  
Author(s):  
Fei Liu ◽  
Min-Ho Jang ◽  
Hyun Dong Ha ◽  
Je-Hyung Kim ◽  
Yong-Hoon Cho ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Graphene Oxide ◽  
Graphene Quantum Dots ◽  
Pristine Graphene ◽  
Synthetic Method ◽  
Green Luminescence ◽  
Graphene Oxide Quantum Dots

Graphene oxide derived graphene quantum dots with different photoluminescence properties and peroxidase-like catalytic activity

RSC Advances ◽  
2016 ◽  
Vol 6 (56) ◽  
pp. 50609-50617 ◽  
Author(s):  
Duosi Tang ◽  
Jingjing Liu ◽  
Xiaomei Yan ◽  
Longtian Kang
Keyword(s):  
Quantum Dots ◽  
Graphene Oxide ◽  
Catalytic Activity ◽  
Graphene Quantum Dots ◽  
Photoluminescence Properties

We demonstrate that there are basically two kinds of GO-derived GQDs with different photoluminescence properties and peroxidase-like catalytic activity.

scholarly journals Detection of Heavy Metals in Water Using Graphene Oxide Quantum Dots: An Experimental and Theoretical Study

Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5519
Author(s):  
Lorenzo Gontrani ◽  
Olivia Pulci ◽  
Marilena Carbone ◽  
Roberto Pizzoferrato ◽  
Paolo Prosposito
Keyword(s):  
Heavy Metals ◽  
Quantum Dots ◽  
Graphene Oxide ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Theoretical Study ◽  
Graphene Quantum Dots ◽  
Emission Spectra ◽  
Optical Response ◽  
Graphene Oxide Quantum Dots

In this work, we investigate by ab initio calculations and optical experiments the sensitivity of graphene quantum dots in their use as devices to measure the presence, and concentration, of heavy metals in water. We demonstrate that the quenching or enhancement in the optical response (absorption, emission) depends on the metallic ion considered. In particular, two cases of opposite behaviour are considered in detail: Cd2+, where we observe an increase in the emission optical response for increasing concentration, and Pb2+ whose emission spectra, vice versa, are quenched along the concentration rise. The experimental trends reported comply nicely with the different hydration patterns suggested by the models that are also capable of reproducing the minor quenching/enhancing effects observed in other ions. We envisage that quantum dots of graphene may be routinely used as cheap detectors to measure the degree of poisoning ions in water.

scholarly journals Electrochemical Method To Prepare Graphene Quantum Dots and Graphene Oxide Quantum Dots

ACS Omega ◽  
2017 ◽  
Vol 2 (11) ◽  
pp. 8343-8353 ◽  
Author(s):  
Satyaprakash Ahirwar ◽  
Sudhanshu Mallick ◽  
Dhirendra Bahadur
Keyword(s):  
Quantum Dots ◽  
Graphene Oxide ◽  
Electrochemical Method ◽  
Graphene Quantum Dots ◽  
Graphene Oxide Quantum Dots
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