Potentiostatic Current-to-Electrochemiluminescence Conversion for Real Time Detection of Low-Intensity Faradaic Events: Application to Nano-Impact Electrochemistry

We present an original opto-electrochemical approach for the real-time conversion of low faradaic currents into electrochemiluminescence (ECL) signals. Under potentiostatic control, the electrochemical reaction of interest occurs at a working ultramicroelectrode (UME), while a second UME, used as a counter electrode, functions as an optical reporting site. ECL emission is generated at this electrode by a luminol derivative with H₂O₂. We demonstrate a nearly perfect linear correlation between the current generated at the working electrode and the ECL intensity emitted from the counter electrode, thereby validating the current-to-ECL conversion principle for both steady-state and transient signals. Furthermore, we successfully apply this conversion scheme to detect electrocatalytic nanoimpact events. Single platinum nanoparticle collisions produce discrete current spikes that are translated simultaneously into ECL bursts. These findings prove that current-to-ECL conversion is a promising strategy for the high-bandwidth, high-sensitivity detection of faradaic events in advanced nanoelectrochemistry applications.