Post-modification by low-temperature annealing of carbon nano-onions in the presence of carbohydrates

The structural and electrochemical properties of carbon nano-onions (CNOs) were investigated in the solid phase, for both plain as well as post-modified CNOs in the absence/presence of carbohydrates (glucose or starch) in an air atmosphere. The structural properties of the CNOs were changed as a consequence of the post-modification during low-temperature annealing. This process changes the carbon structures into predominantly higher ordered graphitic layers. udies clearly showed that polygonization of the CNOs occurred during the annealing process, corresponding to the creation of some of diamond-like structures with predominantly spherical-CNO and ribbon-like graphite structures. Additional graphitization led to an increase of the BET specific surface area, and reached a maximum of 511 m2 g−1 for the post-modified CNOs/starch material. According to the pore size distribution curves of the BJH adsorption, we estimated the pore diameter sizes mainly between the 2 and 50 nm diameter. ectrochemical properties of the CNO films depend on the porous structures of the carbon surface. In aqueous solutions, all CNO films show the typical behavior of an ideal double layer capacitor. The voltammetric behavior of CNO films depends on the counter-ions.