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

## TL;DR

Scientists found a way to activate copper sites on a catalyst by heating it, improving hydrogenation reactions.

## Contribution

A thermal aging strategy is introduced to modulate metal-support interactions in Cu/CeO2 catalysts, unlocking hydrogenation activity.

## Key findings

- Thermal aging at 800°C lowers the reduction temperature and increases the reduction degree of Cu sites.
- Reversible aggregation-redispersion of Cu sites is observed, leading to active metallic Cu nanoparticles.
- The catalytic activity for acetylene semihydrogenation is significantly enhanced on metallic Cu sites.

## 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.

Thermal aging unlocks the hydrogenation capability of inactive Cu species on CeO2 via a dynamic structural change.