How Pt Influences H₂ Reactions on High Surface-Area Pt/CeO₂ Powder Catalyst Surfaces

Area of Science:

• Heterogeneous catalysis
• Surface science
• Materials chemistry

Background:

• Platinum-group metals (PGMs) like platinum (Pt) enhance ceria (CeO2) redox reactions.
• Model studies show PGMs facilitate H2 dissociation and spillover on CeO2 surfaces.
• Understanding PGM effects on powder catalysts, unlike model systems, is crucial.

Purpose of the Study:

• Investigate the mechanism of Pt nanoclusters and single atoms on H2 reactions on Pt/CeO2 powder catalysts.
• Reconcile findings from model systems with real powder catalyst behavior.
• Elucidate the role of spatial heterogeneity in PGM-promoted reactions.

Main Methods:

• Controlled synthesis of Pt/CeO2 powder catalysts.
• Temperature-programmed reduction (TPR) to study H2 consumption.
• In situ infrared spectroscopy (IR) and electron energy loss spectroscopy (EELS) for mechanistic insights.

Main Results:

• Pt significantly enhances H2 consumption rates, even at low Pt loading, indicating spillover beyond Pt-CeO2 interfaces.
• Pt alters H2 activation mechanisms, impacting Ce3+, oxygen vacancy, and water formation rates.
• Ce3+ formation is localized at CeO2-CeO2 boundaries in Pt/CeO2, unlike the homogeneous distribution on pure CeO2.
• Surface reconstruction at CeO2-CeO2 boundaries facilitates faster H2 consumption.

Conclusions:

• Spatial heterogeneity in powder catalysts critically influences PGM-promoted H2 reactions on CeO2.
• Pt's effect extends beyond direct interfaces, involving spillover and surface reconstruction.
• This study bridges the gap between model studies and practical powder catalyst applications.