Complete Degradation of Glassy Carbon Microspheres into Carbon Nanostructures: Implications for Sensing

Glassy carbon (GC) is a well-known carbon material consisting of sp2 hybrid carbon and having fullerene-like nanostructures. GC is recognized to have several advantages, such as good electroconductivity, low density, gas- and liquid-impermeability, high resistance to graphitization, unusual hardness, and good chemical inertness. However, in our recent investigation, we found for the first time that microsized GC microspheres could be completely transformed into nanostructures by concentrated nitric acid (HNO3) treatment, showing that GC did not have good chemical inertness upon exposure to oxidizing acids such as HNO3. The resultant products contain large amounts of GC-based graphene-like quantum dots, graphene-like oxide nanosheets, and some non-degradable graphite-like nanoparticles. This work not only provides an insight into chemical properties and structures of GC but also suggests an easy and efficient way to obtain strongly fluorescent and electrochemiluminescent carbon-based quantum dots implicated for sensitive chemo- and bio-sensors.