Abstract
Core-shell nanoparticles often exhibit improved catalytic properties due to the lattice strain created in these core-shell particles. Herein, we demonstrate the synthesis of core-shell Au@Pd nanoparticles from their core-shell Au@Ag/Pd parents. This strategy begins with the preparation of core-shell Au@Ag nanoparticles in an organic solvent. Then, the pure Ag shells are converted into the shells made of Ag/Pd alloy by galvanic replacement reaction between the Ag shells and Pd2+ precursors. Subsequently, the Ag component is removed from the alloy shell using saturated NaCl solution to form core-shell Au@Pd nanoparticles with an Au core and a Pd shell. In comparison with the core-shell Au@Pd nanoparticles upon directly depositing Pd shell on the Au seeds and commercial Pd/C catalysts, the core-shell Au@Pd nanoparticles via their core-shell Au@Ag/Pd templates display superior activity and durability in catalyzing oxygen reduction reaction, mainly due to the larger lattice tensile effect in Pd shell induced by the Au core and Ag removal.
Highlights
Alloyed counterparts or to mixtures of monometallic nanoparticles[20,21]
We report the synthesis of bimetallic Au-Pd nanoparticles with a core-shell construction and investigate their electrocatalytic properties toward Oxygen reduction reaction (ORR)
Core-shell Au@Ag nanoparticles with an Au core and an Ag shell are firstly prepared by reducing the Ag+ precursors in the presence of pre-synthesized Au seed particles in oleylamine
Summary
The STEM-EDX analysis (Fig. 3e) of the arbitrarily chosen single particle in Fig. 3c illustrates the significant abatement of Ag component in core-shell Au@Ag/Pd nanoparticles after treatment with saturated NaCl solution, indicating the successful removal of Ag from Ag/Pd alloy shell region. We reported the design and synthesis of the bimetallic Au-Pd nanosystems with a core-shell construction to enhance their electrocatalytic activity for room-temperature oxygen reduction reaction This strategy involves the preparation of core-shell Au@Ag/Pd nanoparticles with an Au core and an Ag/Pd alloy shell, and the removal of Ag component from the alloy shell region using saturated NaCl solution. The lattice tensile strain in the Pd shell imposed by the Au core and Ag removal balance the bond-breaking and bond-making steps in the ORR process, rendering the core-shell Au@Pd nanoparticles as-prepared to display superior ORR activity and durability at room temperature. The concept developed in this work may be extended to explore the fabrication of other bimetallic core-shell structures with favorable lattice strain effect for given technical applications
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