In situ atomic force microscopy of electrochemically activated glassy carbon

Glassy carbon (GC) electrodes were activated by anodic oxidation at a poten tial of 1.95 V standard calomel electrode in 1 M H2SO4. The activated elect rodes were investigated by in situ contact atomic force microscopy. In orde r to monitor differences between activated and nonactivated areas, part of the electrode surface was covered by a polymeric varnish during electrochem ical activation. The edge between activated and nonactivated regions was an alyzed after removal of the varnish. The surface of the activated region wa s significantly higher than that of the nonactivated region, indicating sig nificant swelling of the GC during anodic oxidation. After drying, the acti vated film collapsed. Swelling of the activated layer was a linear function of activation time and depended on the state of the electrode. In the oxid ized state the film thickness was larger than in the reduced state. (C) 199 9 The Electrochemical Society. S1099-0062(98)08-111-5. All rights reserved.