Probing the Role of Copper Dislocation Density in Electrochemical CO2 Conversion.

The electrochemical CO2 reduction reaction (CO2RR) is a promising pathway for sustainable carbon utilization with the potential to produce valuable multicarbon (C2+) products, including platform chemicals, like ethanol and ethylene, to replace fossil-fuel-derived sources. While structural defects on catalysts, such as dislocations, have been linked to enhanced CO2RR activity, a deep understanding of the connection between defect structure and selectivity remains elusive. In this work, we directly observe the relationship between dislocation density, catalytic activity, and selectivity in CO2RR on Cu. To investigate this, we synthesized (100)-oriented Cu thin films with systematically controlled dislocation densities spanning a 9-fold range (6.40 × 1014 m-2 to 58.56 × 1014 m-2), measured over the bulk catalyst via X-ray diffraction θ/2θ scans. Dislocation densities were quantified via the Scherrer equation in combination with Le Bail full profile decomposition. In our carefully controlled thin-film samples, the CO2RR and C2 partial current densities did not increase with dislocation density under H-cell testing conditions, indicative of a null result. Overall, we suggest that these findings clarify that higher dislocation density alone does not guarantee greater C2+ activity or selectivity on copper. Our findings suggest that C2+ production may depend on the combination of copper defect structure together with other factors, such as local microenvironment conditions or specific active-site features, which together influence C2+ selectivity. These insights clarify to what extent lattice dislocations alone can influence reaction pathways, resolve discrepancies in the existing literature, and guide the design of CO2RR systems to produce desirable C2+ products.