Spatio-temporal mapping of the redox potential in the Belousov-Zhabotinsky reaction using an uninsulated carbon fiber microelectrode in scanning electrochemical microscopy

Abstract

In this work, we introduce a method that uses an uninsulated carbon fiber microelectrode as a potentiometric Scanning Electrochemical Microscopy (SECM) probe to investigate the Belousov–Zhabotinsky (BZ) reaction. We demonstrate that two-dimensional electrochemical scanning is achievable with a single electrode, as opposed to the stationary electrode measurements commonly reported for the BZ reaction in the present literature. Our approach allows even a highly sensitive reaction like the distributed BZ reaction to proceed undisturbed during measurement. While we chose redox potential as a proof-of-concept parameter due to its straightforward validation against established optical methods, the same setup is readily adaptable to measure other parameters – such as bromide ion concentration or pH – by simply replacing the microelectrode tip. By ensuring that the carbon fiber tip barely contacts the surface, we avoided the need for insulation and minimized disturbances that might otherwise affect the reaction. This work also demonstrates the significant potential of SECM with carbon fiber tips, particularly for scanning within the upper micrometers of a gas-liquid interface, exploiting the flatness of this interface.