Quantum Dots From Coal

Superman can take a lump of coal and squeeze it into a diamond. But for high-tech applications, such as photovoltaics, the Man of Steel might want to take a cue from researchers at Rice University and go for a different carbon allotrope. James M. Tour, Angel A. Martí, and coworkers have shown that it’s possible to synthesize graphene quantum dots—nano­scale carbon particles just a few atoms thick—from coal (Nat. Commun. 2013, DOI: 10.1038/ncomms3943). Other methods for making graphene quantum dots require expensive processes or chemical precursors and produce only small amounts of material. The Rice researchers found that they could create graphene quantum dots from inexpensive and abundant coal by using a single-step wet-chemical process. Coal, they explain, is made up of nanometer-sized crystalline carbon domains linked by aliphatic amorphous carbon. Crushing the coal and bathing it in acid breaks up the amorphous carbon and releases the crystalline quantum dots. The resulting nanoparticles could find use in many applications, including biomedical imaging and optoelectronics.