3D Elemental Mapping and Structural Analysis of Au-Cu-Ag Nanorods—Revealing Heterogeneity for Enhanced CO₂ Reduction and Alcohol Production

The electrochemical conversion of CO₂ from the air into valuable products, such as hydrocarbons, offers an effective solution to environmental issues like the greenhouse effect. Among these valuable products, alcohols are particularly desirable due to their ease of storage, transportation, and high energy density. In cases where CO₂ is reduced to a high concentration of CO, copper (Cu) can further promote C-C bonding and the production of C₂+ alcohols. The Au-Cu-Ag nanorods we have synthesized serve as an ideal catalyst, with their tips capable of generating strong plasmonic excitation upon light irradiation, which facilitates the reduction of CO₂ to CO. By incorporating Cu into the Au nanorods, CO generated at the tips can further react at other regions of the nanorods to form alcohols. Notably, we performed 3D characterization of the trimetallic nanorods, including elemental mapping using EDS tomography to investigate copper distribution at different positions, EELS analysis to determine the copper oxidation state, and STEM tomography to explore phase and structural variations. These studies enabled us to establish structure-property relationships crucial for optimizing catalyst performance.