Multiscale Morphological Evolution of Gas-Diffusion Electrodes Under CO2RR Conditions

Marinos Dimitropoulos^a, Barbara Polesso^a, Viktoria Golovanova^a, Tengyu Chen^a, David Kernan^a, Aparna M. Das^a, F. Pelayo Garcia de Arquer^a

^aICFO - Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), 08860, Spain

Proceedings of MATSUS Spring 2026 Conference (MATSUSSpring26)

G6 Operando and Correlative Characterization of Sustainable Materials and Interfaces

Barcelona, Spain, 2026 March 23rd - 27th

Organizers: Florian Hausen and Svetlana Menkin

Oral, Marinos Dimitropoulos, presentation 576
Publication date: 15th December 2025

Gas-diffusion electrodes (GDEs) enable high current densities in CO₂ electroreduction (CO₂RR), yet they often degrade via flooding, salt precipitation or catalyst detachment[1]. Despite extensive ex-situ analyses on pre-catalysts and post-mortem samples, a direct, time-resolved picture of how these processes unfold from the nanometer to millimeter scale under relevant operating conditions remains elusive. This is notoriously challenging due to the continuous bubble nucleation that disturbs the probe-sample interface[2]. Herein, we combine in-situ electrochemical atomic force microscopy (EC-AFM) with large-area, high-throughput optical profilometry (OP), to quantify GDE reconstruction across scales during CO₂RR and correlate it with catalyst efficiency. We designed an open flow cell that preserves gas transport and diffusion, minimizing bubble formation and allowing the investigation of our catalyst’s surface. EC-AFM mapping of the GDE (nm²) resolves nanoscale roughness evolution, phase restructuring, and particle nucleation, which is more prominent at the grain boundaries. Correlative OP maps of stitched areas (mm²) reveal mesoscale buckling and phase migration which constitute large scale electrode imperfections that can impact stability and performance. By synchronizing electrochemical readouts with both imaging streams, we can link morphological descriptors to performance decay, distinguishing reversible wetting from irreversible structural damage. Ways to stabilize or suppress reconstruction are also investigated by coating the GDEs with polymers (Nafion), which also promote selectivity and reactivity[3]. Complementary to these findings, nanoscale spectroscopic characterization with Tip-Enhanced Raman Scattering (TERS) allows us to evaluate the catalyst chemical structure before CO₂RR. Correlative and multi-scale in-situ methodology is shown to provide mechanistic guidance for GDE architecture by pinpointing the active sites and translating this information to efficient and sustainable catalyst design, ultimately prolonging stable CO₂RR at industrially relevant current densities.

References:

[1] F. P. G. de Arquer et al., CO2 electrolysis to multicarbon products at activities greater than 1 A cm−2, Science, 367,661-666 (2020)

[2] N. T. Nesbitt and W. A. Smith, Operando Topography and Mechanical Property Mapping of CO2 Reduction Gas-Diffusion Electrodes Operating at High Current Densities, J. Electrochem. Soc., 168 044505 (2021)

[3] B. Polesso et al., Chemostructurally Stable Polyionomer Coatings Regulate Proton-Intermediate Landscape in Acidic CO2 Electrolysis, J. Am. Chem. Soc., 147, 31, 27278–27288 (2025)

Acknowledgements:

The authors acknowledge funding from the European Research council (ERC) Starting grant NASCENT (ID 101077243), Marie Skłodowska-Curie actions grant WILDCAT (101150029) and PID2022-138127NA-I00 project funded by the MCIN/AEI/10.13039/501100011033/ FEDER, UE

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