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.

Described is a straightforward procedure for forming organized substrate-immobilized nanoprisms which are single crystalline, surfactant-free and which form a heteroepitaxial relationship with the underlying substrate. The devised route utilizes truncated Au octahedrons formed through solid state dewetting techniques as high temperature heterogeneous nucleation sites for Ag adatoms which are arriving to the substrate surface in the vapour phase. Observed is a morphological and compositional transformation of the Au structures to triangular nanoprisms comprised of a homogeneous AuAg alloy. During this transformation, the localized surface plasmon resonance red-shifts, broadens and increases in strength. The shape transformation, which cannot be rationalized using thermodynamic arguments dependent on the surface energy minimization, is described in terms of a kinetically driven growth mode, previously predicted by molecular dynamic simulations. The so-formed structures, when coated with a thin layer of Pd, are demonstrated as plasmonic sensing elements for hydrogen detection.

We report microstructure analyses and superconducting radiofrequency (SRF) measurements of large scale epitaxial MgB 2 films. MgB 2 films on 5 cm dia. sapphire disks were fabricated by a Hybrid

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Bulk niobium Superconducting Radio-Frequency cavities are a leading accelerator technology. Their performance is limited by the cavity loss and maximum acceleration gradient, which are negatively affected by vortex penetration into the superconductor when the peak magnetic field at the cavity wall surface exceeds the vortex penetration field (Hvp). It has been proposed that coating the inner wall of an SRF cavity with superconducting thin films increases Hvp. In this work, we utilized Nb ellipsoid to simulate an inverse SRF cavity and investigate the effect of coating it with magnesium diboride layer on the vortex penetration field. A significant enhancement of Hvp was observed. At 2.8 K, Hvp increased from 2100 Oe for an uncoated Nb ellipsoid to 2700 Oe for a Nb ellipsoid coated with ~200 nm thick MgB2 thin film. This finding creates a new route towards achieving higher acceleration gradient in SRF cavity accelerator beyond the theoretical limit of bulk Nb.