Synthesis and properties of Cu–Pd hydrosol: Hydrogen reduction of Cu2+ ions catalyzed by palladium nanoparticles

Abstract

A method has been developed for obtaining Cu–Pd hydrosols via catalytic reduction of copper ions by hydrogen on seed palladium nanoparticles 2.5 ± 0.3 nm in size. It has been found that reduction of Cu²⁺ to metal proceeds stage-by-stage through the formation of an intermediate Cu⁺ ion. Cu–Pd hydrosol remains stable with respect to sedimentation and aggregation for several weeks. The hydrodynamic size of Cu–Pd nanoparticles increases proportionally to the copper content in particles. It has been shown that this is due to an acidification of the solution as a result of H⁺ ions formation via the reaction of reduction of Cu²⁺ ions by hydrogen.