(Invited) In Situ Study of Catalyst Structural Evolution during CO₂ Electroreduction by Development of Electrochemical Liquid Cell TEM

The electrocatalytic CO 2 reduction reaction (CO 2 RR) has attracted significant interest of study in the exploration of sustainable energy and environment. Cu-based materials have demonstrated the capability of converting CO 2 to multi-carbon products with high catalytic activity and low cost. Since the performance of heterogenous catalysts is highly susceptible to the catalyst structural changes, unveiling the structure and catalytic active sites during reactions is crucial to the understanding of catalytic mechanisms. Although lots of efforts have been made, it remains a challenge to directly image the atomic structure of a working catalyst in liquid electrolytes due to technical difficulties. Here, I will show our development of in-situ electrochemical liquid cell transmission electron microscopy (TEM) for the study of Cu catalysts during electrocatalytic CO 2 RR. The novel electrochemical liquid cell allows unprecedented atomic imaging of the catalyst evolution during electrochemical reactions. Our observations reveal that the Cu catalyst-electrolyte interaction under an applied potential (-1.1 v) leads to structural changes of Cu catalyst surfaces. Intermediate structure dynamics have been captured. The propagations and transformations of intermediates result in atomically rough Cu crystal surfaces. The intermediates are further found mediating the mass loss of Cu. Control experiments demonstrate the intermediates can be utilized for enhanced carbon-carbon coupling and the formation of two carbon products. Insights gained from this study are not only valuable to designing novel catalysts, but also useful for understanding of electrified solid-liquid interfaces in general.