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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.
Author(s) -
Santos Carla S.,
Lima Alex S.,
Battistel Dario,
Daniele Salvatore,
Bertotti Mauro
Publication year - 2016
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.201501082
Subject(s) - microelectrode , scanning electrochemical microscopy , amperometry , electrode , potentiometric titration , substrate (aquarium) , chemistry , analytical chemistry (journal) , iridium , inorganic chemistry , reproducibility , platinum , materials science , electrochemistry , chromatography , catalysis , oceanography , geology , biochemistry
Abstract The fabrication of a gold microelectrode modified with iridium oxide film (IrO x ) 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 IrO x modified microelectrode was applied successfully in SECM experiments involving the local proton consumption during the nitrate reduction at a copper cathode surface.