Interfacial reaction-directed synthesis of a ceria nanotube-embedded ultra-small Pt nanoparticle catalyst with high catalytic activity and thermal stability

Abstract

A catalyst based on ceria nanotube-embedded ultra-small Pt nanoparticles was synthesized by means of an interfacial reaction in the absence of any surfactant and without involving any separate surface modification process. When Ce(OH)CO₃ nanorods and H₂PtCl₆ are introduced into a NaOH aqueous solution in sequence, a solid–liquid interfacial reaction between Ce(OH)CO₃ and NaOH occurs. The formed Ce(OH)₃ then deposits on the external surface of Ce(OH)CO₃ nanorods. During the interfacial reaction, the negatively charged Pt species is expected to be electrostatically attracted to gradually formed Ce(OH)₃ due to its positive charge, resulting in a uniform mixture of Pt species and Ce(OH)₃. After removing residual Ce(OH)CO₃ and hydrogen reduction, ceria nanotube-embedded Pt nanoparticle hollow composites were achieved. Due to the ultra-small size of catalytically active Pt nanoparticles and the close contact between Pt and ceria, the catalyst exhibits high catalytic activity toward CO oxidation and excellent thermal stability even at temperatures as high as 700 °C, suggesting that they also hold promise for higher temperature catalytic reactions.