Effect of Oxide Chemistry on Pt Redistribution and Site Exposure in ALD-Coated Catalysts

The development of sinter-resistant catalysts is critical for improving the longevity and efficiency of emission control systems. Atomic layer deposition (ALD) has been used to deposit thin, porous oxide materials on supported catalysts to enhance their thermal stability and resistance to sintering. In this study, we investigate the encapsulation of platinum (Pt) catalysts with common metal oxides (Al2O3, ZrO2, and TiO2) using ALD to deepen our understanding of this strategy for catalyst stabilization. Through a combination of structural characterization and catalytic performance testing using propene combustion as a model reaction, we demonstrate that ALD-derived metal oxide coatings effectively mitigate Pt particle agglomeration in all cases studied. We also find that after catalyst aging at 850 °C, small Pt clusters are formed in the ALD catalysts by migration of Pt species within the oxide ALD layers, contributing to higher activity for propene oxidation, particularly for the Al2O3 ALD catalyst. Combining experimental and theoretical insights, we correlate the higher activity of the Al2O3 ALD catalyst with an optimal Pt-oxide interaction that enables Pt redistribution while preserving accessible active sites. These findings highlight the potential of ALD as a strategy for designing durable catalysts with improved performance under high-temperature conditions. The insights gained from this work contribute to advancing catalyst technologies for cleaner energy and environmental applications.