Ultrafine Bimetallic PdCo Alloy Nanoparticles on Hollow Carbon Capsules: An Efficient Heterogeneous Catalyst for Transfer Hydrogenation of Carbonyl Compounds

Abstract

Monodispersed ultrafine bimetallic palladium–cobalt alloy nanoparticles (PdxCoy) are prepared and immobilized on hollow carbon capsules (HCCs). Studies on the effect of metal composition on the catalytic activity of the PdxCoy reveal that the nanoparticulate alloy with the atomic composition of Pd36Co64 is more active than the Co and Pd monometallic nanoparticles in the transfer hydrogenation of carbonyl compounds. The composition of the catalyst and its alloy formation are extensively characterized, and a variety of ketones and aldehydes are hydrogenated successfully with excellent yield and high turnover number (TON), displaying the ability of the synthesized ultrafine Pd36Co64 bimetallic nanoalloy to attain and retain both high catalytic activity and stability. This catalytic system is heterogeneous, stable and does not require additives for activation. Other advantages include milder reaction conditions (does not use gaseous hydrogen), low metal content (0.17 mol %) for a catalytic transfer hydrogenation reaction, functional group tolerance, environmentally benign nature, and reusability.