Insights into $C{O}_2$ activation on defective ZnS surfaces

In this work, we investigate $C{O}_2$ activation on ZnS using Near Ambient-Pressure X-ray photoelectron spectroscopy measurements (NAP-XPS) and density functional theory calculations (DFT). Our NAP-XPS experiments reveal that $C{O}_2$ adsorbs onto a defective ZnS surface upon heating above $473K$ in a $C{O}_2$ atmosphere (up to $0.55mbar$). The $C{O}_2$ adsorption fingerprint is detectable even after cooling to room temperature under ultra-high vacuum. Our DFT calculations suggest that $C{O}_2$ adsorption is energetically favorable on ZnS surfaces containing zinc vacancies, highlighting defect sites as key adsorption centers. Additionally, oxygen adsorption on a defective ZnS surface is exothermic, in contrast to the endothermic behavior observed on a defect-free surface. These findings contribute to a deeper understanding of defect-driven surface reactivity and may inform ZnS-based catalyst’s design for $C{O}_2$ capture and reutilization.