Glassy carbon electrodes II.: Modification by immersion in AgNO3

The modification of glassy carbon by immersion in AgNO3 solution was studied by cyclic voltammetry, vacuum techniques (AES and XPS) and STM. The influence of Ag+ concentration, time of immersion, the presence of oxygen in AgNO3 solution and previous thermal treatment of the glassy carbon were examined on 'as received' (untreated), polished and electrochemically treated samples. The results show that glassy carbon electrode immersed in AgNO3 solution is modified by silver, which is deposited in its elemental state on the surface and near surface layers of the material. Cyclic voltammograms of silver-modified glassy carbon electrodes are similar to those of a silver electrode. The quantity of silver deposited on glassy carbon strongly depends on the pretreatment of the material before its immersion. The results obtained suggest that functional groups participate in the reduction of Ag+, and thus in the electrode modification, as active centers. Metal particles are not uniformly deposited on the surface and the deposition is 3-dimensional with deposits of laminar structure. A mechanism for the modification process is proposed. (C) 2001 Elsevier Science Ltd. All rights reserved.