Volume 28, Issue 7 p. 1441-1447
Full Paper

Fabrication and Use of Dual-function Iridium Oxide Coated Gold SECM Tips. An Application to pH Monitoring above a Copper Electrode Surface during Nitrate Reduction.

Carla S. Santos

Corresponding Author

Carla S. Santos

Institute of Chemistry, University of São Paulo, Av. Professor Lineu Prestes, 748, 05508-000 São Paulo, Brazil

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Alex S. Lima

Alex S. Lima

Institute of Chemistry, University of São Paulo, Av. Professor Lineu Prestes, 748, 05508-000 São Paulo, Brazil

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Dario Battistel

Dario Battistel

Department of Environmental Science, Informatics and Statistics, University Cà Foscari Venice, Via Torino 155, 30127 Venice, Italy

Institute for the Dynamics of Environmental Processes – CNR, University Ca' Foscari of Venice, Via Torino 155, 30123 Venice, Italy

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Salvatore Daniele

Salvatore Daniele

Department of Molecular Sciences and Nanosystems, University Cà Foscari Venice, Via Torino 155, 30127 Venice, Italy

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Mauro Bertotti

Mauro Bertotti

Institute of Chemistry, University of São Paulo, Av. Professor Lineu Prestes, 748, 05508-000 São Paulo, Brazil

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First published: 12 February 2016
Citations: 22

Abstract

The fabrication of a gold microelectrode modified with iridium oxide film (IrOx) and its use as tip with a dual function in SECM experiments is reported. The defective structure of the coating onto the microelectrode surface was used as strategy to combine the advantages of both amperometric (for current-distance determination) and potentiometric (for pH sensing) SECM operation modes. Approach curves, using oxygen and hexaammineruthenium(III) as redox mediators, were obtained without significant loss of the performance and reproducibility of the potentiometric pH response. This allowed the precise positioning of the proposed tip above a substrate in SECM experiments and, subsequently, to monitor pH at the substrate surface. The IrOx modified microelectrode was applied successfully in SECM experiments involving the local proton consumption during the nitrate reduction at a copper cathode surface.