Study on the growth mechanism of Pt nanoparticles in oxides: Role of metal-oxide interactions.

Strong interactions of metal nanoparticles (NPs) with oxide matrices can dramatically enhance the thermal stability of metal NPs. However, how metal-oxide interactions control the growth of metal NPs remains unclear. Here, the growth of Pt NPs with respect to metal-oxide interactions was investigated by encapsulating them in different Al 2 O 3 and SiO 2 oxides. Pt NPs encapsulated in Al 2 O 3 exhibited excellent thermal stability than those in SiO 2. Quantitative thermodynamic calculations revealed that metal-oxide interactions strongly governed the driving force for the coalescence of Pt in Al 2 O 3 and SiO 2. The kinetic analysis further showed that stronger Pt-Al 2 O 3 interactions controlled the Ostwald ripening of Pt NPs by restricting the diffusion of Pt atoms in oxides, leading to a higher growth activation energy of Pt in Al 2 O 3 than SiO 2. These findings explain the different sinter resistance of metal NPs when encapsulated in different oxides, providing valuable insights for enhancing the thermal stability of metal NPs. [Display omitted] [ABSTRACT FROM AUTHOR]