Volume 23, Issue 3 p. 595-603
Full Paper

Ex Situ Scanning Electrochemical Microscopy (SECM) Investigation of Bismuth- and Bismuth/Lead Alloy Film-Modified Gold Electrodes in Alkaline Medium

Maiara Oliveira Salles

Maiara Oliveira Salles

Institute of Chemistry, University of São Paulo, Av. Professor Lineu Prestes, 748, 05513-970 São Paulo, Brazil

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Dario Battistel

Dario Battistel

Department of Physical Chemistry, University of Venice, Calle Larga, S. Marta, 2137, 30123 Venice, Italy tel. +39 041 2348630; fax +39 041 2348594

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Alex Silva Lima

Alex Silva Lima

Institute of Chemistry, University of São Paulo, Av. Professor Lineu Prestes, 748, 05513-970 São Paulo, Brazil

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Mauro Bertotti

Mauro Bertotti

Institute of Chemistry, University of São Paulo, Av. Professor Lineu Prestes, 748, 05513-970 São Paulo, Brazil

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Salvatore Daniele

Corresponding Author

Salvatore Daniele

Department of Physical Chemistry, University of Venice, Calle Larga, S. Marta, 2137, 30123 Venice, Italy tel. +39 041 2348630; fax +39 041 2348594

Department of Physical Chemistry, University of Venice, Calle Larga, S. Marta, 2137, 30123 Venice, Italy tel. +39 041 2348630; fax +39 041 2348594Search for more papers by this author
First published: 22 December 2010
Citations: 7

Abstract

Scanning electrochemical microscopy (SECM) in feedback mode was employed to characterise the reactivity and microscopic peculiarities of bismuth and bismuth/lead alloys plated onto gold disk substrates in 0.1 mol L−1 NaOH solutions. Methyl viologen was used as redox mediator, while a platinum microelectrode was employed as the SECM tip. The metal films were electrodeposited ex situ from NaOH solutions containing either bismuth ions only or both bismuth and lead ions. Approach curves and SECM images indicated that the metal films were conductive and locally reactive with oxygen to provide Bi3+ and Pb2+ ions. The occurrence of the latter chemical reactions was verified by local anodic stripping voltammetry (ASV) at the substrate solution interface by using a mercury-coated platinum SECM tip. The latter types of measurements allowed also verifying that lead was not uniformly distributed onto the bismuth film electrode substrate. These findings were confirmed by scanning electron microscopy images. The surface heterogeneity produced during the metal deposition process, however, did not affect the analytical performance of the bismuth coated gold electrode in anodic stripping voltammetry for the determination of lead in alkaline media, even in aerated aqueous solutions. Under the latter conditions, stripping peak currents proportional to lead concentration with a satisfactory reproducibility (within 5 % RSD) were obtained.