Work

Surface compositional modification of Weyl semimetal Co3Sn2S2(0001) from vacuum to electrochemical water splitting conditions

Year: 2024

Type: article

Abstract: This study investigates the surface compositional evolution of the topological Weyl semimetal Co3Sn2S2, proposed to be an active catalyst for water splitting, from ultra high vacuum (UHV) to catalytic reaction conditions, using synchrotron X-ray spectroscopy (XPS). We found that the surface cleaved in ambient air is completely oxidized, forming Co oxides and Sn oxides/hydroxides. This surface exhibits an overpotential of 503 mV to achieve a current density of 10 mA cm-2 for OER. However, the UHV-cleaved surface maintains Co3Sn2S2 pristine features, showing remarkably slow kinetics compared to the air-cleaved sample. Systematically tracking the oxidation process under various exposure conditions reveals that Sn exhibits activity towards oxygen and water vapor under UHV and demonstrates a strong interaction with liquid water at ambient conditions. In contrast, higher exposed pressure promotes Co oxidation, resulting in the formation of Co oxides in atmospheric air, which correlates with enhanced catalytic activity. Despite unfavorable evidence regarding the surface robustness, this work provides crucial insights into Co3Sn2S2 surface reactivity.

Source: Applied Surface Science

DOI: 10.1016/j.apsusc.2024.162046