Electronic properties and double layer of activated carbon

According to the ion exchange, between the electrolyte in the pores and the external electrolyte, as well as to the conductivity of the solid material, the large charge capacity of the activated carbon under investigation does not arise from redox properties of surface groups but from mobile charge carriers in the solid. The dependence of the conductivity (minimum value 1000 S m(-1)) and of the thermopower on the electrode potential and on the temperature shows that the mechanism of the electronic conduction resembles neither that of metals nor of semiconductors. It is characterized as ''hopping'' between electronically coherent domains and resembles the process in conducting polymers. According to e.s.r. measurements, the spin density is low and does not change markedly with the potential. The prevalence of paired charges is proposed as a hypothetic explanation. (C) 1997 Elsevier Science Ltd.