Green Preparation of High Yield Fluorescent Graphene Quantum Dots from Coal-Tar-Pitch by Mild Oxidation.

Quanrun Liu,Baolin Xing,He He,Jianbo Jia,Guangxu Huang,Chuanxiang Zhang,Jingjie Zhang

doi:10.3390/nano8100844

Quanrun Liu, Baolin Xing + Show 5 more

Open Access

https://doi.org/10.3390/nano8100844

Copy DOI

Journal: Nanomaterials	Publication Date: Oct 17, 2018
Citations: 81	License type: CC BY 4.0

Affiliation: Henan Polytechnic University, Jiaozuo University

Abstract

Coal tar pitch (CTP), a by-product of coking industry, has a unique molecule structure comprising an aromatic nucleus and several side chains bonding on this graphene-like nucleus, which is very similar to the structure of graphene quantum dots (GQDs). Based on this perception, we develop a facile approach to convert CTP to GQDs only by oxidation with hydrogen peroxide under mild conditions. One to three graphene layers, monodisperse GQDs with a narrow size distribution of 1.7 ± 0.4 nm, are obtained at high yield (more than 80 wt. %) from CTP. The as-produced GQDs are highly soluble and strongly fluorescent in aqueous solution. This simple strategy provides a feasible route towards the commercial synthesis of GQDs for its cheap material source, green reagent, mild condition, and high yield.

Highlights

In recent years, graphene has attracted more and more attention due to its unique properties [1], such as excellent mechanical properties [2], thermal properties [3] and electronic properties [4]; it has a wide range of applications on optoelectronics, energy storage, biomedical, catalysis, sensors and among many others [5,6,7,8]
The surface elements and functional groups of the Coal tar pitch (CTP) were characterized by X-ray photoelectron spectroscopy (XPS) and summed up in Supplementary Figure S2a,b and Tables S1 and S2
The C1s high-resolution XPS reveals that there are high Csp3 content due to their abundant side chains and other amorphous carbon linking on the edges of CTP molecules, which are easier to oxidize than pure sp2-carbon

Summary

Introduction

Graphene has attracted more and more attention due to its unique properties [1], such as excellent mechanical properties [2], thermal properties [3] and electronic properties [4]; it has a wide range of applications on optoelectronics, energy storage, biomedical, catalysis, sensors and among many others [5,6,7,8]. GQDs are generally derived from glucose, carbon fibers, graphite, graphene oxides, and synthesized or fabricated by methods like electrochemical oxidation, lithographic patterning, hydrothermal, microwave, acidic oxidation and supercritical fluid treatment [15,17,18,19,20,21,22,23,24,25,26,27,28]. The high price of the carbon source (graphite, carbon fibers, and carbon nanotubes), long processing time (24–48 h), post-purification procedure (3–5 days) and the harsh reaction conditions (nitrating mixture or oxidizing supercritical water) for the large-scale production of GQDs are uneconomic and unreasonable, so it is imperative and desirable to prepare GQDs in a more facile, milder and more environmentally-friendly method [18,19,21,23,24,29,30].

Methods

Results

Conclusion