Chemoresistive Response of Nanoporous Activated Carbon Fibers Upon Hydrofluorocarbons Treatment

The thermal resistivity method, which is a convenient and sensitive to electrical resistance changes, was proposed for control of chemical modification of nanoporous activated carbon fibers (NACF) with hydrofluorocarbons (HFC). The surface state changes could be monitored by measuring Ohmic resistance during heating, physisorption, and chemical reaction between the activated carbon material and HFC. Thus, we found a correlation between the fluorine content in the resulted carbon material and electrical resistance, measured from the room temperature to 900 °C. It was shown that in this way the temperature of the beginning of a chemical reaction and the temperature of the most effective chemical modification could be determined. The thermal grafting of fluororganic groups onto NACF is assumed to be the reason for the changed electrical resistivity of the initial NACF.