For electrochemical CO2 reduction reaction (CO2RR) to become a viable technology for the reuse of waste carbon dioxide, reasonably active, selective, and durable catalysts must be developed. A holistic understanding of the fundamental processes taking place during operation of such catalysts can be gained by using advanced operando techniques that can complement characterization pre and post operation. These techniques can provide experimental evidence on mechanisms of catalyst restructuring, agglomeration, and degradation, configuration of key intermediates, and localization of active sites. In particular, electrochemical liquid-phase transmission electron microscopy (TEM) can provide morphological, structural, and chemical information with remarkable temporal and spatial resolution. However, the applicability of the technique to the electrochemical CO2RR remains challenging. Issues have to do with the wide inert potential range requested for performing quantitative electrochemistry on the microelectrodes, which is also associated with background hydrogen gas generation that can inhibit interpretability of the results. Herein, we will discuss the advancements of the confined TEM microcells that allow to study CO2RR processes in real-time. We will show results of various shapes and sizes of state-of-the-art Cu catalysts and we will describe the mechanisms responsible for their evolution during the first stages of CO2RR by applying electron imaging and diffraction methodologies. The fundamental understanding of the processes responsible for CO2RR catalyst reconstruction gained by liquid-phase TEM can motivate future research on long-term stable catalysts.

Liquid-phase transmission electron microscopy diagnostics of CO2 reduction reaction catalysts

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.