Tin surface atomic layers on gallium-tin liquid alloys for CO2 electrochemical reduction

Abstract

Liquid metal alloys form quasi‑ordered atomic layers at their electrolyte interfaces. We show that electrocapillarity, or charging the interface under cathodic bias, tunes the surface composition, enabling either enrichment of the lower‑surface‑energy component or its expulsion. This tunability provides a means to optimise catalytic sites for multi-step electrochemical reactions. Here, we investigate surface enrichment in gallium-tin (Ga–Sn) liquid alloys for electrochemical CO2 reduction. Applying a half-cell potential of –1.20 V vs. RHE to liquid Ga91.6Sn8.4 in 0.10 M KHCO3 increases the surface excess concentration of Sn, forming a highly active and stable Sn atomic layer for the electroc..