Scheme 6. Schematic Drawing Representing the Main Operando SEPM Configurations for CO₂RR Interrogation.

The catalyst is polarized to perform CO₂RR (red arrows), while the SEPM tip is positioned as a spectator, where the tip response depends on the actuator method. (i) SG-TC-SECM with the tip polarized to oxidize CO (CO₂RR product). (ii) SECM tip monitors the local OH^– activity variation using the Pt/PtO potential. (iii) SG-TC-SECM tip registers H₂ oxidation (gray arrow). (iv) EC-STM mapping of a polarized surface performing CO₂RR.