Simulation of the Effect of Shear Stress on Coal Particle in the Preparation of Coal-based Carbon Quantum Dots by Ball Milling

Abstract

Since carbon quantum dots were discovered in 2004, they have received significant attention. So far, the synthesis and applications of carbon quantum dots are still in the early stage of development. Among the synthesis methods, ball milling garnered widespread attention. However, there is controversy regarding whether ball milling can be employed for large-scale production of carbon quantum dots from coal. Whether van der Waals bonds between graphite layers in coal particles can be broken during ball milling is the key to the feasibility of using ball milling to synthesize coal-based carbon quantum dots. Therefore, in this study, we simulated this microscopic process with a two-dimensional model. After applying shear stress, the proportions of broken van der Waals bonds in anthracite and bituminous coal particles were found to be 53.26% and 74.55% at 2500th iterations, respectively. The graphite layers in anthracite coal particles could not be exfoliated sufficiently due to the larger size of graphite layers in anthracite coal compared to that of bituminous coal. This study explores the feasibility of preparing carbon quantum dots from coal by ball milling and offers guidance for the selection of raw materials.