Anthracite
is a plentiful and affordable natural resource with
a high coalification degree and many graphene-like sp2 carbon
crystallites, which is fascinating for the development of novel coal-based
carbon materials to achieve the value-added utilization of coal resources.
In this work, a facile one-step ultrasonic physical tailoring procedure
for the fabrication of blue luminescent coal-derived graphene quantum
dots (C-GQDs) was exploited using Taixi Anthracite as the carbon source.
The as-prepared C-GQDs possess uniformly distributed sizes and diameters
of 3.2 ± 1.0 nm, and their aqueous solution can remain in stable
homogeneous phase even after 2 months at room temperature. Moreover,
we found that the C-GQDs exhibit two different distinctive emission
modes. The evolution of the surface states and the electronic structure
analysis revealed that two different types of fluorescence centers
could be ascribed to nanosized sp2 carbon domains and oxygen
functional group defects. Meanwhile, unique electronic and chemical
properties endow the C-GQDs with a sensitive response to Cu2+. C-GQDs were demonstrated as potential fluorescent materials for
reliable, label-free, and selective detection of Cu2+,
showing great promise in real-world sensor applications.
There is much recent interest in graphene-based composite electrode materials because of their excellent mechanical strengths, high electron mobilities, and large specific surface areas. These materials are good candidates for applications in supercapacitors. In this work, a new graphene-based electrode material for supercapacitors was fabricated by anchoring carbon dots (CDs) on reduced graphene oxide (rGO). The capacitive properties of electrodes in aqueous electrolytes were systematically studied by galvanostatic charge-discharge measurements, cyclic voltammetry, and electrochemical impedance spectroscopy. The capacitance of rGO was improved when an appropriate amount of CDs were added to the material. The CD/rGO electrode exhibited a good reversibility, excellent rate capability, fast charge transfer, and high specific capacitance in 1 M H2SO4. Its capacitance was as high as 211.9 F/g at a current density of 0.5 A/g. This capacitance was 74.3% higher than that of a pristine rGO electrode (121.6 F/g), and the capacitance of the CD/rGO electrode retained 92.8% of its original value after 1000 cycles at a CDs-to-rGO ratio of 5:1.
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