Noble metallic nanoparticles (NPs) become a great scientific and industrial interest due to their unique physicochemical properties, and play important roles for a number of catalytic applications, such as oxidation and reduction reactions, environmental catalyzes, fuel cells and energy storage. Among these, platinum NPs (Pt NPs) have been receiving large attention because they are the most efficient and common catalyst for both anodes and cathodes in fuel cells. Multi-metallic Pt-based NPs were reported for enhancement of catalytic properties in comparison to monometallic Pt NPs, while reducing the Pt consumption [1]. Although possessing such potentials, the synthetic techniques for multi-metallic NPs have not yet achieved the controllability over the NPs morphology and structure, unless going through complex reaction conditions. In this study, Au@Ag@Pt core@multi-shell NPs were synthesized in one-pot by facile co-reduction method, a combination of galvanic replacement reaction (GRR) and a co-reducing agent, to obtain a well-defined nanostructure with enhanced surface area of Pt towards catalytic applications. The as-synthesized NPs were found to have Au core covered by Ag-Pt double-shell, which contained a degree of hollows with the inner surface composed of both Ag and Pt, while the outer surface composed of granular Pt. The shell-formation mechanism will also be discussed in aspect of competition role between GRR and co-reduction reactions, under the influence of unique charge transfer effect from Au core to Ag middle shell [2]. The NPs were characterized with UV-Vis, DLS, and especially high-end electron microscopic techniques, including ADF-STEM and EDS elemental mapping. Through understanding the complexity of the reaction mechanism, one can expect to design and fabricate various types of trimetallic nanoparticles with intricate structures, thus further expanding their nanotechnology and applications.

Formation of multi-shell Au@Ag@Pt nanoparticles by co-reduction method

ACS Fall 2021

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