P123-stabilized Au–Ag alloy nanoparticles for kinetics of aerobic oxidation of benzyl alcohol in aqueous solution

Colloidal Au–Ag alloy nanoparticles with various Ag/Au molar ratios were first prepared by a co-reduction method in P123 aqueous solution and characterized by UV–vis, TEM, and XPS. The prepared Au–Ag alloy nanoparticles were substantially stable and had comparable particle sizes (3–4 nm) for aerobic oxidation kinetics of benzyl alcohol. The addition of Ag not only significantly enhanced the reaction rate but also increased the apparent activation energy (Ea) compared to that for monometallic Au nanocatalysts. The kinetics investigations indicated that on the pure Au sites, the oxidation of benzyl alcohol followed 1.5-order reaction kinetics, while on Au sites adjacent to Ag atoms, it followed 0.5-order reaction kinetics. The presence of Na2CO3 greatly improved the catalytic activity of Au–Ag nanocatalysts but decreased the selectivity to benzaldehyde.