Solid state dewetting of ultrathin films is the most straightforward means of fabricating substrate-supported noble metal nanostructures. This assembly process is, however, quite inflexible, yielding either densely packed smaller structures or widely spaced larger structures. Here, we demonstrate the utility of introducing a sacrificial antimony layer between the substrate and noble metal overlayer. We observe an agglomeration process which is radically altered by the concurrent sublimation of antimony. In stark contrast with conventional dewetting, where the thickness of the deposited metal film determines the characteristic length scales of the assembly process, it is the thickness of the sacrificial antimony layer which dictates both the nanoparticle size and interparticle spacing. The result is a far more flexible self-assembly process where the nanoparticle size and areal density can be varied widely. Demonstrations show nanoparticle areal densities which are varied over four orders of magnitude assembled from the identical gold layer thickness, where the accompanying changes to nanostructure size see a systematic shift in the wavelength of the localized surface plasmon resonance. As a pliable self-assembly process, it offers the opportunity to tailor the properties of an ensemble of nanostructures to meet the needs of specific applications.

The galvanic replacement of sacrificial templates offers one of the most synthetically viable approaches for generating platinum-based nanostructures with impressive catalytic activity. Here, we present template design criteria for the synthesis of morphologically smooth platinum nanoshells which undergo minimal alloying with the template material. The criteria is founded on comparisons of nanoshells derived from reacting substrate-immobilized templates of silver, lead, copper, nickel, and cobalt with aqueous H2PtCl6. It is shown that template-surface modifications are the primary mode by which smooth Pt nanoshells are obtained, with template composition playing a secondary role. The degree of alloying is strongly dependent upon whether the template applies tensile or compressive heteroepitaxial strains to the depositing nanoshell. On the basis of these findings, we propose a mechanistic framework and an overall strategy for the synthesis of advanced templates for substrate-based galvanic replacement reactions.

A substrate-based templated assembly route has been devised which offers large-area, high-throughput capabilities for the fabrication of periodic arrays of sub-micrometer and nanometer-scale structures. The approach overcomes a significant technological barrier to the widespread use of substrate-based templated assembly by eliminating the need for periodic templates having nanoscale features. Instead, it relies upon the use of a dynamic template with dimensions that evolve in time from easily fabricated micrometer dimensions to those on the nanoscale as the assembly process proceeds. The dynamic template consists of a pedestal of a sacrificial material, typically antimony, upon which an ultrathin layer of a second material is deposited. When heated, antimony sublimation results in a continuous reduction in template size where the motion of the sublimation fronts direct the diffusion of atoms of the second material to a predetermined location. The route has broad applicability, having already produced periodic arrays of gold, silver, copper, platinum, nickel, cobalt, germanium and Au-Ag alloys on substrates as diverse as silicon, sapphire, silicon-carbide, graphene and glass. Requiring only modest levels of instrumentation, the process provides an enabling route for any reasonably equipped researcher to fabricate periodic arrays that would otherwise require advanced fabrication facilities.

The reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride serves as a well-established model reaction for assessing the catalytic activity of metal nanoparticles. While many of the studied nanoparticles are plasmonic in nature, there is little understanding of whether significant photocatalytic enhancements to the reaction rate are achievable. Here, we assess the catalytic and photocatalytic properties of highly faceted, substrate-immobilized nanoprism-like AuCu structures synthesized using a vapor phase templated-assembly technique.The so-formed structures have a bimetallic composition which is well-recognized for its catalytic capabilities as well as a strong localized surface plasmon resonance in the visible spectrum which gives rise to enhanced near-fields at the tips of the triangle. Using a dip catalyst modality, the structures are demonstrated as heterogeneous photocatalysts with a 32-fold enhancement to the reaction rate when resonantly illuminated with 10 mW/cm 2 laser light. The study demonstrates the potential of such structures as photocatalysts and validates the reduction of 4-nitrophenol as a reaction useful in assessing the photocatalytic capabilities of plasmonic nanostructures.

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