Conjugated dual size effect of core-shell particles synergizes bimetallic catalysis

Abstract

Core-shell bimetallic nanocatalysts have attracted long-standing attention in heterogeneous catalysis. Tailoring both the core size and shell thickness to the dedicated geometrical and electronic properties for high catalytic reactivity is important but challenging. Here, taking Au@Pd core-shell catalysts as an example, we disclose by theory that a large size of Au core with a two monolayer of Pd shell is vital to eliminate undesired lattice contractions and ligand destabilizations for optimum benzyl alcohol adsorption. A set of Au@Pd/SiO2 catalysts with various core sizes and shell thicknesses are precisely fabricated. In the benzyl alcohol oxidation reaction, we find that the activity increases monotonically with the core size but varies nonmontonically with the shell thickness, where a record-high activity is achieved on a Au@Pd catalyst with a large core size of 6.8 nm and a shell thickness of ~2–3 monolayers. These findings highlight the conjugated dual particle size effect in bimetallic catalysis.

Large Au@Pd/PdOx core–porous shell nanoparticles as efficient ethanol oxidation electrocatalysts

“…11 Of these, Au-Pd bimetallic NPs with core-shell structures are the most studied for the following reasons: the Au core could have a positive effect on the durability and stability of the catalysts; the strain and electronic effects between Au and Pd could adjust the d-band centre of Pd and lower the adsorption energy of the intermediates; and the introduced Au facilitates the oxidation of the intermediates and thus enhances the catalytic activity. [12][13][14][15] As is well known, strain and electronic effects occur in Au@Pd core-shell NPs with a few atomic layers of Pd shell and its surface, respectively. A great scientific effort has been devoted to the preparation of Au@Pd core-shell NPs with different morphologies and structures.…”

Tuning the surface properties of AuPd nanoparticles for adsorption of O and CO

“…We considered different structures of AuPd (fcc and Ih) because particles with fcc and Ih structures have been experimentally synthesized. 11,29 The amorphous structure was chosen because nanoparticles can be used in high-temperature catalysis when the closest packed structure of nanoparticles can change to the amorphous structure. [30][31][32][33][34] Amorphous nanoparticles were obtained by MD modelling the fcc melting of AuPd nanoparticles and rapid freezing of the amorphous structure.…”

“…The catalytic efficiency of core-shell nanoparticles can be increased more than ten times compared to their monometallic counterparts. [8][9][10][11] This is due to the following factors: firstly, charge redistribution at the core-shell interface and the appearance of a dimensional quantum effect in the case of an atom-thin shell. 9,12 Another important factor is the deformation of the metallic shell due to the lattice mismatch between the core and shell which leads to changes in the electronic properties.…”

“…9,12 Another important factor is the deformation of the metallic shell due to the lattice mismatch between the core and shell which leads to changes in the electronic properties. 13 Recent work by Zhang et al 11 has shown that selecting the specific sizes of the core and shell of Au@Pd nanoparticles leads to a significant increase in their catalytic activity. However, such tuning of nanoparticle properties requires a detailed understanding of the processes occurring at the core-shell interface and at the nanoparticle surface.…”

Ultrathin core–shell–satellite structured Au@PtPd@Pt nanowires for superior electrocatalytic hydrogen evolution

“…Recent advancements have also unveiled the potential of core-shell nanostructures in facilitating the systematic design and synthesis of high-performance Pt-based catalysts with tailored morphologies and compositions. [11][12][13][14] For instance, Zeng and co-workers have successfully synthesized ultrathin Pt nanoshells at the subnanoscale on finely AgPd alloy cores, which enhances both the activity and stability of the HER by dually optimizing the lattice strain and electron effects. 14 However, the shell regions in the core-shell structure usually exhibit smooth and dense surfaces, which could pose challenges for guest species to access the inner cores, thereby diminishing the benefits of the core-shell structure.…”