Enhanced Catalytic Performance for Hydrogenation of Substituted Nitroaromatics over Ir-Based Bimetallic Nanocatalysts.

IrM (M = Fe, Co, and Ni) alloy nanoparticles (NPs) were synthesized in a solution by employing butyllithium as a reduction agent and oleylamine as a stabilizing agent, and the alumina-supported IrM bimetallic nanoparticles were tested for selective hydrogenation of various substituted nitroaromatics. The relevant characterizations including X-ray diffraction, X-ray photoelectron spectra, transmission electron microscopy, and diffuse reflectance fourier transform infrared with CO probes confirm that IrM NPs are uniform alloys. The obtained IrM/Al2O3 catalysts show significantly enhanced catalytic activity as well as selectivity relative to individual monometallic Ir catalysts, indicating a unique catalytic property of bimetallic alloy nanostructures. Among these bimetallic catalysts, IrNi/Al2O3 illustrate the highest activity and selectivity for hydrogenation of various substituted nitroaromatics. Calculations by density functional theory suggest that bimetallic structures of IrNi facilitate the reactant adsorption and product desorption, resulting in enhanced catalytic performance.