Reversible aggregation-redispersion of Cu sites in Cu/CeO₂ catalysts with unlocked hydrogenation activity.

Abstract

For oxide-supported metal catalysts, metal-support interaction (MSI) facilitates metal dispersion at the expense of the metallic character, resulting in a trade-off between active site utilization and intrinsic activity. Here, we used a thermal aging strategy to modulate the MSI in Cu/CeO₂ catalysts, facilitating the formation of metallic Cu sites upon H₂ reduction while maintaining metal dispersion. Systematic experiments confirmed that thermal aging at 800°C lowered the reduction temperature and increased the reduction degree of Cu sites. Microscopy evidenced few-atom-layered Cu nanoclusters before and after H₂ reduction, whereas in situ spectroscopy revealed metallic Cu nanoparticles under H₂ atmosphere. This discrepancy indicated a reversible structural evolution from aggregation to redispersion in thermally aged Cu/CeO₂. The catalytic activity for acetylene semihydrogenation was unlocked on metallic Cu sites, compared to nearly inactive Cu sites in conventional Cu/CeO₂ counterparts. Our work developed an effective strategy for rational modulation of MSI, offering the feasibility to tailor-make active sites for specific reactions.