Understanding Reconstruction Dynamics on Porous Electrodes Tailored for CO₂ Reduction by In-Situ Electrochemical Atomic Force Microscopy

Classical electrochemical techniques, such as cyclic voltammetry, can provide vital information on the catalyst electrochemical interface, yet they remain suggestive in determining reconstruction dynamics at the nanoscale. In situ/operando characterization with nanoscale spatial resolution is paramount for understanding, regulating, and tuning the local electrochemical functionalities. Electrochemical Atomic Force Microscopy (EC-AFM) has been proven as a revealing method for characterizing catalysts under realistic CO₂ reduction (CO₂RR) conditions, in-situ<i> </i>^[1]. Furthermore, controlling the reaction microenvironment at the catalyst-electrolyte interface with inorganic and organic additions is an established approach to promote reactivity, selectivity, and stability ^[2],[3],[4]. The rational design of these electrocatalysts requires detailed knowledge of spatial property variations across their interface. By linking reactivity and reconstruction, stable and efficient electrodes can be engineered on-demand.<br/>Herein, advanced AFM tools have provided novel insights into locally probed electrochemical mechanisms with nanometer resolution. The structure-property relationships of porous electrodes (Polytetrafluoroethylene/Cu) and their heterojunctions with organic coatings (Nafion) are disentangled, and the impact of reconstruction dynamics on their catalytic activity is highlighted. Complementary to these findings, nanoscale spectroscopic characterization with Tip-Enhanced Raman Scattering (TERS) allows us to evaluate the catalyst chemical structure before CO₂RR. The engineered catalysts are ultimately assessed in real catalytic conditions for CO₂RR for the generation of C2+ products. In situ/operando tools are shown to provide a viable pathway to fine-tune electrochemical processes by pinpointing the active sites and translating this information to efficient and sustainable catalyst design.<br/><br/><br/><b><u>References</u></b><br/>[1] Simon G. et al. Potential-Dependent Morphology of Copper Catalysts During CO2 electroreduction revealed by in situ Atomic Force Microscopy. Angewandte Chemie, 60, 5, 2561-2568 (2021)<br/><br/>[2] Huang, Jianan Erick, et al. CO2 electrolysis to multicarbon products in strong acid. Science, 372.6546 (2021): 1074-1078.<br/><br/>[3] Xie, Y., Ou, P., Wang, X. et al. High carbon utilization in CO₂ reduction to multi-carbon products in acidic media. Nat Catal 5, 564–570 (2022).<br/><br/>[4] Zhao, Y., Hao, L., Ozden, A. et al. Conversion of CO2 to multicarbon products in strong acid by controlling the catalyst microenvironment. Nat. Synth 2, 403–412 (2023).