Synthesis and stabilization of small Pt nanoparticles on TiO2 partially masked by SiO2

Abstract

Controlling metal nanoparticle size and preserving metal dispersion at elevated temperature remain key challenges in designing new supported metal catalysts. Many methods have been proposed to stabilize metal nanoparticles for catalysis, but the use of specialized equipment or metal precursors can limit the application of these methods for scalable production. Here, we demonstrate a synthesis strategy to improve the dispersion and thermal stability of Pt nanoparticles on an oxide support. A thin SiO2 coat (<2 nm) was deposited on TiO2 through repeated condensation cycles of tetraethyl orthosilicate (TEOS) with or without an organic template on the surface. H2PtCl6 was deposited using wetness impregnation, and the samples were dried, calcined, and reduced. The as-synthesized Pt nanoparticles are 1–2 nm by TEM and maintain dispersion >45% by CO chemisorption even after prolonged heating at 500 °C, whereas Pt nanoparticles on unmodified TiO2 are less dispersed (∼33%) and their dispersion falls further upon prolonged heating. Ethylene hydrogenation demonstrates that the Pt nanoparticles on modified TiO2 preserve the catalytic activities of Pt on unmodified TiO2. The use of wet chemistry-based oxide modification and wetness impregnation makes this strategy a scalable and generalizable synthesis method to prepare other supported metal nanoparticles for catalysis applications.