Electrodes E1 to E6 use commercially available a-C material, as a reference. The a-C electrodes contain activatedcarbon belonging to the same supplier. They are made withvarious conditions in order to obtain active layer with awell-defined sticking and cohesiveness. Of the differentforms of carbon, a-C is particularly attractive as an ECDLelectrode because of its low cost, high specific surface areaof about 1000 m2 g−1 and optimum density per surface area.The physical characteristics of the various active materialswere measured and are compared in Table 3.