Revealing of Nanocracking of CuO-Derived Cu Nanocatalysts During CO₂ Electroreduction Using Operando Multimodal Electrochemical Liquid Cell TEM and X-Ray Methods

Driven by physical and chemical adsorption at the catalytic surfaces, nanocatalysts often experience restructuring during catalytic reactions. Inactive precatalysts can transform into active catalysts under reaction conditions, such as oxide-derived Cu (OD-Cu) for CO₂ electroreduction reaction (CO₂RR) displaying improved production of multicarbon (C₂₊) chemicals. Identifying and controlling active sites during electrocatalytic reactions is often challenging but critically important for the designing nanocatalysts with improved catalytic performance. This requires in situ/operando characterizations of structure, morphology, and valence state evolution with high spatial and temporal resolution. Here, we have conducted operando studies of OD-Cu catalysts evolution from CuO bicrystal nanowires during CO₂RR using a multimodal platform coupling the newly developed high-resolution electrochemical liquid cell transmission electron microscopy (EC-TEM) with time-resolved and high energy resolution fluorescence detected (HERFD-) X-ray absorption spectroscopy (XAS). We discovered the formation pathways of catalytically active sites through nanocracking of CuO bicrystal nanowire precatalysts during rapid reduction to metallic Cu. Electrocatalytic performance testing in reactors of different scales (EC-TEM liquid cell, H-type cell, and membrane electrode assembly (MEA)), coupled with complementary ex situ structural characterizations, suggest the nanocracking behavior is general across all relevant operating conditions and is critical for enhanced C₂₊ activity.

References:
[1] J. Wan, E. Liu, W. Choi, J. Liang, B. Zhang, X. Sun, M. Zhang, H. Xue, K. Kim, Y. Chen, Q. Zhang, C. Wen, J. Yang, K. Bustillo, P. Ercius, D. Leshchev, J. Su, Z. Y. Al Balushi, M. Asta, A. Weber, A. Bell, W. Drisdell, H. Zheng in review (2024).
[2] Q. Zhang, Z. Song, X. Sun, Y. Liu, J. Wan, S. Betzler, Q. Zheng, J. Shangguan, K. Bustillo, P. Ercius, P. Narang, Y. Huang, H. Zheng. Nature 630, 643–647 (2024).
[3] Acknowledgements: The above work was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences (BES), Materials Sciences and Engineering Division under Contract No. DE-AC02-05-CH11231 within the In-situ TEM (KC22ZH) program. Work at the Molecular Foundry (MF) LBNL, which was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.