Reactive AgAuS and Ag₃AuS₂ Synthons Enable the Sequential Transformation of Spherical Nanocrystals into Asymmetric Multicomponent Hybrid Nanoparticles

Abstract

Nanoscale heterostructures that interface with multiple distinct materials provide opportunities to engineer functional complexity into single-particle constructs. However, existing synthetic pathways to such hybrid nanoparticles emphasize surface-seeded growth, which limits the scope of accessible systems. Here, we introduce an alternative approach that transforms isotropic nanocrystals into asymmetric, multicomponent Janus particles through sequential deposition, reactive phase segregation, and cation exchange processes that are mediated by an unusual class of reactive synthons. After Ag−Au seed particles had formed and had reacted with sulfur, a series of segregated Au 1−x Ag x −AgAuS and Au 1−x Ag x −Ag 3 AuS 2 hybrid nanoparticles form. The AgAuS and Ag 3 AuS 2 domains provide a synthetic entryway into solution-mediated cation exchange reactions, with the compositions of the Ag−Au−S synthons defining the components, morphologies, and interfaces of the hybrid nanoparticle products. Upon cation exchange with Pb 2+ , Au 1−x Ag x −AgAuS forms Ag 1−x Au x −PbS heterodimers while Au 1−x Ag x −Ag 3 AuS 2 forms Ag 1−x Au x −Ag 2 S−PbS heterotrimers. The process by which isotropic metal nanoparticles transform into asymmetric hybrid nanoparticles through reactive Ag−Au−S synthons provides important insights that will be applicable to the retrosynthetic design of complex nanoscale heterostructures having expanded multifunctionality and synergistic properties.

Synthesis of Au/CdSe Janus Nanoparticles with Efficient Charge Transfer for Improving Photocatalytic Hydrogen Generation

“…In addition, since a higher pH value also makes glycine a stronger reductant in the first step, the reduction of Ag could be boosted up, and the thickness of Ag wetting layers would increase with pH value of the reaction solution. As a result, more Se atoms are allocated to the process of Ag layer selenization and CdSe growth at high pH environment, which will prolong the Ag 2 Se ripening time and ease the AuAg interfacial etching [48]. Our experiment conducted at different pH environments also confirmed this argument.…”

“…Then, it is inevitable that Se 0 will continue to etch the AuAg alloyed interface. The metal-semiconductor interfaces would further flatten along a certain crystal plane [48]. Meanwhile, the corresponding semiconductor bumps gradually enlarge, as displayed in Fig.…”

Interface and heterostructure design in polyelemental nanoparticles

“…As the field of multiphase, polyelemental NPs progresses toward greater compositional diversity and structural complexity (1,2,(18)(19)(20)(21), understanding how specific classes of interfaces can be established in one particle is crucial for designing new and functional nanostructures. Although NPs have been synthesized and characterized with up to four phases (1,2,(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), there is limited general understanding of why specific architectures form, and the role of surface and interfacial energies in controlling the architecture of NPs with more than two phases is not fully understood.…”

Modulated Triple‐Material Nano‐Heterostructures: Where Gold Influenced the Chemical Activity of Silver in Nanocrystals

“…One of the important observations noticed here was the expected Au(I) ion segregation which was expected due to Ag(I) exchanging with other bivalent or trivalent cations. In the previous report by Li et al, it was observed that the composition of Au and Ag in AuAgS varied where amount of Au(I) increased with time as Ag(I) ions were exchanged. This was clearly reflected from the change in XRD patterns.…”