Steady-State Electrocatalytic Activity Evaluation with the Redox Competition Mode of Scanning Electrochemical Microscopy: A Gold Probe and a Boron-Doped Diamond Substrate

In the current context of energetic transition, investigations of alternative complex systems require tools such as scanning electrochemical microscopy (SECM), offering interesting opportunities as an electroanalytical technique to evaluate innovative catalysts. Herein, we demonstrate how a judicious choice of probe and substrate materials opens up improved performances to achieve steady-state measurements for oxygen reduction reaction (ORR) catalytic activity detection through redox competition scanning electrochemical microscopy (RC-SECM). On the probe side, we show that using gold enhances the stability of the local oxygen concentration detection in comparison to the regularly used platinum one. On the substrate side, we evaluate boron-doped diamond as an appealing alternative to classical support substrate, that shows a low ORR activity, high stability and very good reusability. This work introduces an alternative approach for quantitative measurements with SECM, improving measurement ease, comfort and reproducibility, thus paving the way towards standardized benchmarking and numerical simulation-based parameter extraction.