Progress, status and prospects of non-porous, heteroatom-doped carbons for supercapacitors and other electrochemical applications

A remarkable amount of work on non-porous carbons has been done by few research groups and some important and very interesting features have been described. The conceptual idea of pseudo effect due to heteroatoms in the carbon framework has been expected to give rise to huge specific capacitance from high-density non-porous carbon that will result in high volumetric capacitance. The focus was on their redox activity in electron transfer from electrolyte ion to heteroatoms in carbon electrodes with negligible contribution from the electrical double layer. Various types of interesting structures like nanofibers, and microspheres have been described. The presence of heteroatoms increases the electroactivity of nanofibers and microspheres of carbon and significantly affects their faradaic reactions at electrode-electrolyte interface, which gives surplus pseudocapacitance. As a result of these investigations, non-porous nanostructured carbons decorated with P-, F-, B-, N- and O-heteroatoms in different structural positions have been described. These materials have been provided with excellent pseudocapacitive performance. Many experimental results are being reported here with various electrolytes, for a supercapacitor device and other electrochemical applications.