Synthesis of ultrasmall, homogeneously alloyed, bimetallic nanoparticles on silica supports

Abstract

Supported nanoparticles containing more than one metal have a variety of applications in sensing, catalysis, and biomedicine. Common synthesis techniques for this type of material often result in large, unalloyed nanoparticles that lack the interactions between the two metals that give the particles their desired characteristics. We demonstrate a relatively simple, effective, generalizable method to produce highly dispersed, well-alloyed bimetallic nanoparticles. Ten permutations of noble and base metals (platinum, palladium, copper, nickel, and cobalt) were synthesized with average particle sizes from 0.9 to 1.4 nanometers, with tight size distributions. High-resolution imaging and x-ray analysis confirmed the homogeneity of alloying in these ultrasmall nanoparticles.

Milling Down to Nanometers: A General Process for the Direct Dry Synthesis of Supported Metal Catalysts

“…One example is supported catalysts,which are amultibillion Euro business worldwide, [2] and for which novel synthetic methods are continuously explored. [3][4][5] In the following it is described that aw ide range of different supported catalysts can be produced by simple milling, starting from macroscopic metal powder and as upport material, resulting in nanometer-sized noble metal (and in some cases also base metal) nanoparticles on different supports.T his approach may have very high practical value,s ince milling could become as imple alternative method to the complex solution processing nowadays used in the synthesis of supported catalysts.M oreover, nanoscale dispersion is highly interesting in many other fields,a nd thus these findings have significance also beyond catalysis.…”

Toward an Understanding of Capping Molecules on Pt Nanoparticles for Hydrogenation: the Key Role of Hydroxyl Groups

“…The XPS results of Pt/rGO indicate that Pt 0 and Pt 2+ coexist on rGO with the ratio of 1:1.5 (Figure a). As shown in Figure b, similar XRD patterns between Pt/rGO and rGO indicate highly dispersion of Pt NPs on rGO . Pt NPs dispersed on rGO perform as “spacers” to delimit the stack of rGO nanosheets which caused the intense peak at about 10°.…”

“…As shown in Figure 13b, similar XRD patterns between Pt/rGO and rGO indicate highly dispersion of Pt NPs on rGO. [38] Pt NPs dispersed on rGO perform as "spacers" to delimit the stack of rGO nanosheets [1b] which caused the intense peak at about 10°. In addition, Pt/rGO exhibited IV adsorption curve of mesoporous structure, which is due to the stacked of rGO one-dimension sheets (Figure 13c).…”

Single Metal Atom Photocatalysis

“…It has been reported that, by adjusting the pH of solution, the hydroxyl groups become protonated and thus positively charged below the point of zero charge (PZC), or deprotonated and thus negatively charged above the PZC . Therefore, metal anions like [PtCl 6 ] 2− or cations like [(NH 3 ) 4 Pt] 2+ can be strongly anchored onto the support surface via strong electrostatic adsorption, and thus isolated metal atoms stabilized on the support are obtained by subsequently removing the undesired ligands. Except for the hydroxyl groups, the surface monolayer ethylene glycol groups were also reported to absorb PdCl 4 2− for the formation of an atomically dispersed Pd catalyst under UV irradiation …”