Mapping Spatial and Temporal Electrochemical Activity of Water and CO₂ Electrolysis on Gas-Diffusion Electrodes Using Infrared Thermography

Abstract

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.

Operandocharacterization of continuous flow CO2electrolyzers: current status and future prospects

“…Neutron/X-ray radiography 78,91,100,128,129 Water management Neutron/synchrotron facility Few seconds for X-ray few tenths of seconds for neutron mm -scale (x, y) Gas evolution Limited elemental information Precipitate formation Operando cell failure diagnostics Only minor cell modification needed Thermography 130 Local activity mapping One-to-one correlation between temperature change and activity has to be proved Depends on catalyst substrate, layer thickness, etc. Noninvasive probing to assess activity distribution a XAS: X-ray absorption spectroscopy, SECM: scanning electrochemical microscopy, AFM: atomic force microscopy, MS: mass spectrometry.…”

“…As with the increase of cell size or number of cell stacks, higher spatial variation in operating conditions is expected, probing local activities in a full electrolyzer device can assist scale-up efforts. Recently, location-specific catalytic activity was studied by infrared thermography, 130 making use of the inefficient charge transfer and transport, resulting in heat generation. The authors postulated that any temperature change of the catalyst was primarily because of heat generation from the electrochemical reaction at the cathode.…”

The Necessity for Multiscale In Situ Characterization of Tailored Electrocatalyst Nanoparticle Stability

“…Very often, the electrocatalytic cell for in situ characterization is designed in such a way that the signal intensity is optimized, while reasonable electrocatalytic performance is ensured (low current densities). Recently, temperature measurements with an IR camera were performed and utilized as a direct probe for catalytic activity in a GDE cell (Figure a) . For this purpose, the GDE cell was equipped with an IR transparent window, and the temperature was mapped from the back of the porous GDE.…”

“…Reproduced with permission from ACS Energy Lett. 2022 , 7, 2410–2419 . Copyright 2022 American Chemical Society.…”

Geometric Catalyst Utilization in Zero-Gap CO2 Electrolyzers

“…A way of combining these mass transport effects is by considering geometric catalyst utilization of a CO 2 electrolyzer, which can then be defined as the ratio of the planar catalyst area utilized for CO 2 RR (desired reaction) to the total planar catalyst area present in the system. Recent studies have considered broader mass transport efforts for mapping spatial electrochemical activity and engineering catalyst layers for maximizing multicarbon products from CO 2 RR, − but these have yet to be considered as changing in time.…”