Coal is widely regarded as a low-value and environmentally challenging material, yet it contains abundant carbon that can be converted into useful nanomaterials through sustainable processing. Carbon quantum dots (CQDs) are promising carbon nanomaterials known for their strong photoluminescence, good water dispersibility, and applications in sensing, imaging, and optoelectronic devices [1]. However, most CQD synthesis methods require harsh chemical oxidants or high-temperature treatments, which increase energy consumption and environmental impact. In this work, we present a room-temperature, harsh chemical-free, and flow chemistry approach for converting coal slurry into CQDs using a Vortex Fluidic Device (VFD), which creates dynamic high-shear liquid thin films under ambient conditions [2].
The work presented here uses water and ethanol as green solvents together with confined thin-film flow and UV-C irradiation, enabling carbon transformation without strong chemical reagents or external heating. The unique flow environment inside the VFD creates chemical radicals in-situ [3,4] promoting efficient cleaving and formation of nanoscale fluorescent carbon particles. Structural and optical characterizations confirm the successful production of photoluminescent CQDs with stable emission behavior. Because the process operates at room temperature and avoids harsh chemicals, it significantly reduces both energy consumption and chemical waste compared with conventional synthesis routes.
This study demonstrates a sustainable pathway for converting coal waste into functional carbon nanomaterials and highlights the VFD as a scalable platform for environmentally responsible CQD production.