Controlled synthesis of Pd–NiO@SiO2 mesoporous core–shell nanoparticles and their enhanced catalytic performance for p-chloronitrobenzene hydrogenation with H2

Abstract

In this work, Pd–NiO@SiO₂ core–shell mesoporous nanocatalysts with ~4 nm Pd–NiO heteroaggregate nanoparticle cores and ~17 nm mesoporous silica shells were successfully synthesized by a sol–gel method. The surfactant-capped PdNi alloy nanoparticles were coated with SiO₂ through hydrolysis of tetraethylorthosilicate to obtain PdNi@SiO₂ nanoparticles, and the mesoporous Pd–NiO@SiO₂ core–shell nanocatalysts were formed after removal of surfactants by calcination at 500 °C and subsequent H₂ reduction at 200 °C. The characterization results by XRD, TEM and BET revealed that Pd–NiO@SiO₂ nanocatalysts were highly stable with the maintenance of intact core–shell structures under high-temperature thermal treatments. The Pd–NiO@SiO₂ nanocatalysts illustrated a superior catalytic performance for p-chloronitrobenzene hydrogenation with H₂ to the control Pd@SiO₂ nanocatalysts. The catalytic performance enhancement of Pd–NiO@SiO₂ nanocatalysts is ascribed to the strong interaction between Pd and NiO in the cores, where the interfaces may be beneficial for hydrogenation reactions.