Synthesis of Cerium-Oxide Coated Platinum Core-Shell Structure Catalysts with Enhanced Stability and Activity via Atomic Layer Deposition

Abstract

Platinum nanoparticles (NPs) play an important role in the catalytic applications such as conversion of automotive exhaust, fuel cells, nano sensing and so on. For many of catalytic applications, agglomeration of Pt NPs is undesired because the coalescence results in a decrease of surface active sites.1 Many approaches have been explored to prevent agglomeration, the formation of core shell structures to encapsulate the noble metal nanoparticles seems to be a viable way.2,3 Herein we report the utilization of active oxide layers to encapsulate Pt NPs through atomic layer deposition. Besides the outstanding sintering resistance by physical anchoring, the active oxide decorated composite catalysts have additional metal-oxide interfaces that may further enhance the catalytic activity. HRTEM characterizations and DFT simulations have shown that oxide layers initially preferred to deposit on Pt (111) to form an incontinuous coating layer. The Pt-oxides model catalysts were prepared on planar Al2O3 supports to obtain a molecular level understanding of the catalytic process. It is found that Pt nanoparticles with all kinds of oxide coating layers have demonstrated not only the good sintering resistance under atmosphere condition, but also the lower CO oxidation conversion temperature than bare Pt nanoparticles.