Surface Enrichment in Gallium-Indium Liquid Alloys: Applied to CO₂ Conversion

Liquid metal alloys can accumulate specific solute metal atoms on their surface, creating distinct quasi-ordered atomic layers. Such atomic layers can be tuned by varying the alloy composition to form catalytic interfaces suited for multi-step reactions. Here, the surface enrichment in gallium-indium alloys is studied and utilized for carbon dioxide (CO2) electrochemical reduction. The results show that adding a small amount of indium (16.8 at%) to gallium leads to a significant indium enrichment of >83 at% on the topmost layer of the alloy. This enrichment dictates the CO2 conversion pathway, leading to 98% faradaic efficiency toward formate at -1.90 V vs reversible hydrogen electrode (RHE). This study produces unprecedented insights into key interfacial processes and lays the foundation for significant further work within the areas of catalysis and liquid metals.