Coal-Derived Graphene Quantum Dots Produced by Ultrasonic Physical Tailoring and Their Capacity for Cu(II) Detection

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.