Visualization of spatial electrochemical activity via a combined thermal-electric potentiostat

The electrolysis of water, CO2 and N2 provide options for producing fossil-free fuels and feedstocks at global scales. Technological advancements are challenged by the complexity of phenomena spanning broad physical scales (angstroms to meters) and scientific domains. Further, activity is presently quantified indirectly, hindering disambiguation of catalytic and system effects. Here, we present a spatial thermal-electric potentiostat (STEP) which links local electrochemical activity to an associated operando heat signature. The STEP then directly maps catalytic activity with fine resolutions in temperature (10 mK), time (0.2 s) and space (0.1 mm), capturing operational phenomena as they occur. We demonstrate STEP’s potential for catalyst screening, degradation measurements and spatial mapping through water and CO2 electrolysis experiments up to 0.2 A cm-2. We identify rapid catalytic temperature spikes with activity (>10 K at 0.2 A cm-2) and localized activity fluctuations in operation, both which challenge many perceptions of the electrocatalyst and reaction environment during operation.