▎ 摘　　要

Graphene quantum dots (GQDs), one of the most promising nanoforms of carbon, have shown exceptional physiochemical properties owing to their strong threedimensional quantum confinement. By altering the band gap or edge functionalization in GQDs, the properties can be tuned to meet challenging demands of modern computational and quantum devices. GQDs have primarily been synthesized at the lab scale so far, by both top-down and bottom-up approaches, using various natural or synthetic carbon-rich precursors. Only a few milligrams of the precursor is typically used in the synthesis, and it also involves hazardous acids, bases, or other catalysts, which impose additional time, labor, and cost for their removal. GQDs made hitherto are also functionalized with polar moieties due to the use of acids or bases in the synthesis, resulting in insolubility of GQDs in nonpolar solvents. Herein, an acid/base-free, microwave-assisted pyrolytic process is developed where GQDs of controlled size without any polar functionalities are synthesized using Styrofoam waste as the precursor. The structure of GQDs is confirmed by transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and other spectroscopic analysis, and it is found to be single layered with an average size of 5.5 +/- 1.5 nm. A maximum yield of 15% is obtained by optimizing the pyrolysis temperature and exposure time of the precursor, and GQDs are found to be highly soluble in nonpolar solvents, including toluene and cyclohexane. The obtained GQDs were used as a promising agent to provide durable hydrophobicity and excellent self-cleaning property when coated on cotton fabric. The use of nonbiodegradable polymer waste such as Styrofoam to generate nonpolar GQDs of controlled dimensions provided a complete solution to not only curb deleterious effects of polymeric waste but also enable production of high value-added products for vast applications.