(727d) Synthesis of Supported Bimetallic Nanoparticles Via Surface Inorganometallic Chemistry

Heterogeneous catalysts that contain bimetallic nanoparticles (NPs) are used in many petrochemical processes. In recent years, bimetallic NPs have been used in biomass conversions, electrocatalysis, and many other catalytic processes. Conventional impregnation method usually results in ill-defined bimetallic NPs with inhomogeneous particle sizes and compositions. New strategies for the synthesis of bimetallic NPs include colloidal synthesis, surface organometallic chemistry, atomic layer deposition, coadsorption and coreduction of metal cations, and carbothermal shock synthesis. Nevertheless, the synthesis of ultrasmall (< 3 nm) supported bimetallic NPs with well-defined stoichiometry and intimacy between constituent metals remains challenging.

In this presentation, we will discuss a new strategy for the synthesis of supported bimetallic NPs. Our strategy involves the preassembly of well-defined heterometallic compounds, double complex salts (DCSs), on a substrate. The supported DCSs can be converted to well-defined supported bimetallic NPs upon reduction. The bimetallic nature of these NPs was confirmed by single-NP energy-dispersive x-ray (EDX) spectroscopy analysis. The composition of several individual NPs was also obtained for each sample, as well as large-area EDX spectroscopy analysis to obtain an average composition of each sample. In all cases, the single-NP analysis confirmed that the NPs are bimetallic. This approach can be applied to a large variety of bimetallic NPs, including several bulk immiscible systems. The bimetallic NPs are extremely small and have narrow size distributions. Furthermore, these bimetallic catalysts outperform their parent metals in selective hydrogenation of acetylene.