Glassy carbon electrodes II. Modification by immersion in AgNO3

The modification of glassy carbon by immersion in AgNO3 solution was studie d by cyclic voltammetry, vacuum techniques (AES and XPS) and STM. The influ ence of Ag+ concentration, time of immersion, the presence of oxygen in AgN O3 solution and previous thermal treatment of the glassy carbon were examin ed on 'as received' (untreated), polished and electrochemically treated sam ples. The results show that glassy carbon electrode immersed in AgNO3 solut ion is modified by silver, which is deposited in its elemental state on the surface and near surface layers of the material. Cyclic voltammograms of s ilver-modified glassy carbon electrodes are similar to those of a silver el ectrode. The quantity of silver deposited on glassy carbon strongly depends on the pretreatment of the material before its immersion. The results obta ined suggest that functional groups participate in the reduction of Ag+, an d thus in the electrode modification, as active centers. Metal particles ar e not uniformly deposited on the surface and the deposition is 3-dimensiona l with deposits of laminar structure. A mechanism for the modification proc ess is proposed. (C) 2001 Elsevier Science Ltd. All rights reserved.