CeO2-supported Au38(SR)24 nanocluster catalysts for CO oxidation: a comparison of ligand-on and -off catalysts

Abstract

The catalytic properties of atomically precise, thiolate-protected Au₃₈(SR)₂₄ (R = CH₂CH₂Ph) nanoclusters supported on CeO₂ were investigated for CO oxidation in a fixed bed quartz reactor. Oxygen (O₂) thermal pretreatment of Au₃₈(SR)₂₄/CeO₂ at a temperature between 100 and 175 °C largely enhanced the catalytic activity, while pretreatment at higher temperatures (>200 °C) for removing thiolate instead gave rise to a somewhat lower activity than that for 175 °C pretreatment, and the ligand-off clusters were also found to be less stable. The CO conversion in the case of wet feed-gas (i.e. the presence of H₂O vapor) was appreciably higher than the case of dry feed-gas when the reaction temperature was kept relatively low (between 60 and 80 °C), and interestingly the ligand-on and ligand-off catalysts exhibited opposite response to water vapor. Finally, we discussed some insights into the catalytic reaction involving the well-defined gold nanocluster catalyst.