Co‐digestive Ripening‐Mediated Synthesis of Bimetallic Au–Pd Nanoalloy in Ionic Liquid for Synergistic Catalytic Enhancement in 4‐Nitrophenol Reduction and Phenylacetylene Semihydrogenation

Bimetallic nanoparticles utilize the synergistic properties of their constituent metals, which have a bearing on the catalyst stability, product selectivity, and tunability of the catalyst activity. Noble metal‐based alloys, among various bimetallic structures, are especially appealing due to their electronic tunability and ease of synthesis. Conventional synthesis of bimetallic nanoparticles via wet chemical reduction often involves toxic metal salt precursors, raising safety and environmental concerns in addition to tedious purification procedures and reliability concerns related to reproducibility. This study presents a cleaner synthesis route for Au–Pd nanoalloys, combining solvated metal atom dispersion with co‐digestive ripening in the ionic liquid [C ₁₈ BIm]Br, using pure metals and organic solvents. Varying the Au/Pd molar ratio led to uniform, spherical alloy nanoparticles with minimal polydispersity. The catalytic activity of these nanoalloys was evaluated for the reduction of 4‐nitrophenol, where the equimolar Au:Pd colloid (AuPd@IL) showed excellent performance with an apparent rate constant of 0.52 min ⁻¹ , matching or exceeding literature values. Further testing for phenylacetylene semihydrogenation, a key industrially relevant reaction, using the AuPd@IL catalyst resulted in 91.1% conversion with 91.2% styrene selectivity, outperforming its monometallic counterparts (Au@IL: 23.8% conversion, 75.6% selectivity; Pd@IL: 100% conversion, 6.5% selectivity). These findings underscore the enhanced catalytic properties of Au–Pd nanoalloys due to the synergistic interaction between the two metals, offering clear advantages over individual metal catalysts in practical applications.