Segregation in bimetallic nanoparticles

Abstract

Bimetallic nanoparticles are of interest due to their physical and chemical properties, which differ from their monometallic counterparts, and are dependent on size, composition and structure. Their unique chemical and physical properties make them useful in many optical, electronic and catalytic applications. In this perspective article we discuss segregation in bimetallic nanoparticles and highlight a recent analytical model based on minimization of energy. Computational approaches are discussed, along with a few examples and a comparison with the analytical approach. Experimental evidence for surface segregation is described, and finally, future directions are suggested. From this review of theoretical and experimental information it appears that a general consensus is starting to emerge that there are size-dependent variations in segregation in nanoparticles with the experimental data reasonably consistent with the theoretical models.

Effect of Atomic Ordering on the Activity for Methanol and Formic Acid Oxidation of Pt‐Based Electrocatalysts

“…[35,36] In a random alloy, the overall surface composition depends on the surface segregation of one of the components, which lowers the surface energy. [37] In the case of ordered intermetallics, instead, segregation depends on other factors: for example, most of the surface truncations of a perfectly ordered structure have a composition different from that of the bulk simply for crystallographic reasons. Stamenkovic et al [38] used surface x-ray scattering to determine the near-surface composition of the Pt 3 Ni(111) ordered structure in situ.…”

Synthesis of carbon-supported Pd–Co bimetallic catalysts templated by Co nanoparticles using the galvanic replacement method for selective hydrogenation

“…Bimetallic nanoparticles (NPs) have attracted much attention over the last several decades due to their potential applications as catalysts. [1][2][3][4][5][6] Ligand and ensemble effects in bimetallic catalysts have been reported to dramatically enhance their catalytic activity and selectivity. [7][8][9] These effects depend on the composition, size, morphology and structure of the bimetallic species, [10][11][12] and therefore control of these properties is important in the design of heterogeneous catalysts for specic reactions.…”

Bimetallic Nanoparticles in Alternative Solvents for Catalytic Purposes

“…Commonly, the immobilization of NPs on solid supports permits their stabilization [2][3][4], such as inorganic oxides [5] or carbon-based supports [6], in addition to favoring nanocatalyst recycling. In particular, bimetallic nanoparticles (BMNPs) differ from their corresponding monometallic structures in terms of morphology, composition, and structure, inducing distinctive physical and chemical properties [7]. The synergy between both metal partners, modulated by the different BMNP structural arrangements, introduces a wide diversity in reactivity, mainly due to the electronic tuning of metals [8,9].…”

“…Catalysts 2017,7, 207 24 of 34 at 80 °C and 50 bar of H2 in 4 h) (Scheme 12); clear cooperative effects were observed when compared to the corresponding parent monometallic catalysts (Rh/SBA-15 and Pt/SBA-15). The authors propose an enhanced absorption of arenes mediated by Pt on the active sites, whereas Rh plays a key role in the hydrogenation[133].…”