The global shift toward carbon neutrality has intensified interest in electrocatalytic reactions, such as hydrogen evolution, oxygen reduction, and particularly carbon dioxide reduction (CO₂RR), as promising strategies to reduce greenhouse gas emissions and generate valuable chemical products. In order to design catalysts with high activity, selectivity, and stability, it is essential to understand the fundamental mechanisms involved in electrochemical processes. In situ and operando approaches have emerged as powerful tools for probing catalyst properties under working conditions, enabling deeper insights into their activity, including the identification of active sites, reaction intermediates, and key transformation pathways.

Electrochemical liquid-phase transmission electron microscopy (EC-LPTEM) has gained attention for its ability to observe the evolution of the morphology and crystalline structure of materials in liquid environment, under provision of electrochemical stimulus [1]. EC-LPTEM is a highly demanding technique as it utilizes miniaturized liquid cells with integrated three-electrode configurations, which needs to be compatible with high vacuum and electron-transparent environments [2]. Electrochemical liquid-phase Raman spectroscopy can provide complementary information, in particular on surface species and their dynamic evolution during the reaction [3]. Combining EC-LPTEM with operando Raman spectroscopy provides time-resolved access to morphological, structural, and chemical information. These therefore provide direct evidence of catalyst evolution, contributing to deeper understanding of the catalyst behaviour during reaction.

In this study, we investigate the dynamic evolution of a copper-based catalyst under electrochemical CO₂ reduction conditions by EC-LPTEM, shading light on the structural and morphological changes the material undergoes during electrocatalytic activity. Complementary Raman spectroscopy is introduced to provide additional chemical insight, and the feasibility of employing a shared electrochemical cell platform to enable correlative EC-LPTEM and Raman studies is evaluated. This multimodal approach enables direct correlation of catalysts transformations with catalytic performance, offering mechanistic insights into CO₂RR on Cu-based catalysts and informing future efforts in the knowledge-driven optimization of materials for selective and stable electrocatalysis.