title: Electrochemical modification of gold electrodes with azobenzene derivatives by diazonium reduction.
abstract: An electrochemical study of Au electrodes electrografted with azobenzene (AB), Fast Garnet GBC (GBC) and Fast Black K (FBK) diazonium compounds is presented. Electrochemical quartz crystal microbalance, ellipsometry and atomic force microscopy investigations reveal the formation of multilayer films. The elemental composition of the aryl layers is examined by X-ray photoelectron spectroscopy. The electrochemical measurements reveal a quasi-reversible voltammogram of the Fe(CN)6 (3-/4-) redox couple on bare Au and a sigmoidal shape for the GBC- and FBK-modified Au electrodes, thus demonstrating that electron transfer is blocked due to the surface modification. The electrografted AB layer results in strongest inhibition of the Fe(CN)6 (3-/4-) response compared with other aryl layers. The same tendencies are observed for oxygen reduction; however, the blocking effect is not as strong as in the Fe(CN)6 (3-/4-) redox system. The electrochemical impedance spectroscopy measurements allowed the calculation of low charge-transfer rates to the Fe(CN)6 (3-) probe for the GBC- and FBK-modified Au electrodes in relation to bare Au. From these measurements it can be concluded that the FBK film is less compact or presents more pinholes than the electrografted GBC layer.
authors: Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia.
authors: Elo
authors: E
authors: Kibena
authors: Margus
authors: M
authors: Marandi
authors: Uno
authors: U
authors: Mäeorg
authors: Luna B
authors: LB
authors: Venarusso
authors: Gilberto
authors: G
authors: Maia
authors: Leonard
authors: L
authors: Matisen
authors: Aarne
authors: A
authors: Kasikov
authors: Väino
authors: V
authors: Sammelselg
authors: Kaido
authors: K
authors: Tammeveski