Design of Highly Efficient Pt-SnO₂ Hydrogenation Nanocatalysts using Pt@Sn Core–Shell Nanoparticles

Abstract

In this work, Pt-SnO2 heteroaggregate nanocatalysts were synthesized by in situ transformation of Pt@Sn core–shell nanoparticles and their catalytic performance for hydrogenation of various substituted nitroaromatics was investigated. The Pt@Sn nanoparticles were prepared by a one-step method, and the alumina-supported Pt@Sn nanoparticles were further transformed in situ into Pt-SnO2 heteroaggregate nanostructures by calcination. The structures of Pt@Sn and Pt-SnO2 nanomaterials were characterized, and FT-IR with CO probes, HRTEM, XRD, and XPS characterizations revealed that the as-synthesized Pt@Sn nanoparticles were core@shell-like structures with Sn-rich shells and Pt-rich cores and the obtained Pt-SnO2 heteroaggregate nanostructures consisted of close-contact pure Pt and SnO2 phases. The Pt-SnO2/Al2O3 nanostructures demonstrated a better catalytic performance for hydrogenation of various substituted nitroaromatics relative to individual Pt/Al2O3 nanocatalysts. Theoretical calculations suggested that Pt-SnO2 nanocatalysts can slightly facilitate the adsorption of H2 and o-chloronitrobenzene and strongly weaken the binding of Pt/o-chloroaniline, resulting in more available reactants and easier release of products from the catalyst surfaces. The theoretical calculations indicated that the enhanced catalytic performance may originate from a cooperative interaction between Pt and SnO2.