Enhanced sensitivity of scanning bipolar electrochemical microscopy for O2 detection

Carla Santana Santos; Felipe Conzuelo; Vera Eßmann; Mauro Bertotti; Wolfgang Schuhmann

doi:10.1016/j.aca.2019.08.049

Enhanced sensitivity of scanning bipolar electrochemical microscopy for O₂ detection

Anal Chim Acta. 2019 Dec 9:1087:36-43. doi: 10.1016/j.aca.2019.08.049. Epub 2019 Aug 27.

Authors

Carla Santana Santos¹, Felipe Conzuelo², Vera Eßmann², Mauro Bertotti³, Wolfgang Schuhmann⁴

Affiliations

¹ Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany; Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, Av. Professor Lineu Prestes, 748 05513-970, São Paulo, Brazil.
² Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany.
³ Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, Av. Professor Lineu Prestes, 748 05513-970, São Paulo, Brazil.
⁴ Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany. Electronic address: wolfgang.schuhmann@rub.de.

PMID: 31585564
DOI: 10.1016/j.aca.2019.08.049

Abstract

The Scanning Bipolar Electrochemical Microscope (SBECM) allows precise positioning of an electrochemical micro-probe serving as bipolar electrode that can be wirelessly interrogated by coupling the electrochemical detection reaction with an electrochemiluminescent reporting process. As a result, the spatially heterogeneous concentrations of an analyte of interest can be converted in real time into a map of sample reactivity. However, this can only be achieved upon optimization of the analytical performance ensuring adequate sensitivity. Here, we present the evaluation and optimized operation of the SBECM for the detection of small changes in local O₂ concentrations. Parameters for achieving an improved sensitivity as well as possibilities for improving the signal-to-noise ratio in the optical signal readout are evaluated. The capability of the SBECM for O₂ detection is shown at controlled conditions by recording the topography of a patterned sample and monitoring O₂ evolution from a photoelectrocatalyst material.

Keywords: Alternating current; Bipolar electrochemistry; Closed bipolar electrode; Contactless detection; Electrochemiluminescence; Oxygen detection.