Controlled Pt Doping of Silica-Supported Ni Nanoparticles through Surface Organometallic Chemistry on Metals: Applications as Catalysts for Selective Hydrogenation Reactions

Abstract

Silica-supported Ni/Pt nanoparticles were synthesized through the selective Pt doping of silica-supported Ni nanoparticles using an original approach that can be considered as a Surface OrganoMetallic Chemistry on Metals (SOMC@M). The targeted bimetallic nanoparticles were obtained via the selective grafting of Pt(COD)Me2 onto the surface of the nickel nanoparticles. The resulting solids were fully characterized using several techniques, including infrared spectroscopy, HAADF-STEM, and HRTEM with EDX, confirming the successful incorporation and uniform distribution of Pt centers onto the Ni nanoparticles without side deposition of Pt onto the silica support. These experimental observations were also supported by Density Functional Theory (DFT) calculations. Further H2 treatments at 500 °C were applied to the Pt-grafted Ni NPs to enable the removal of surface Pt ligands and the diffusion of Pt atoms into the Ni nanoparticles. This SOMC@M methodology was able to secure the precise control over Pt loading and Pt distribution within the Ni NPs, key parameters for enhancing catalytic performance. The resulting materials were found to exhibit remarkable selectivity in both the hydrogenation of 4-nitrostyrene and the semihydrogenation of hex-3-yn-1-ol, demonstrating the potential of SOMC@M as a versatile approach for the design of tunable and efficient bimetallic catalysts.