A Comparative Plasmonic Study of Nanoporous and Evaporated Gold Films

Previously, we have reported that nanoporous gold (NPG) films prepared by a chemical dealloying method have distinctive plasmonic properties, i.e., they can simultaneously support localized and propagating surface plasmon resonance modes (l-SPR and p-SPR, respectively). In this study, the plasmonic properties of NPG are quantified through direct comparison with thermally evaporated gold (EG) films. Cyclic voltammetry and electrochemical impedance spectroscopy experiments reveal that the NPG films have 4–8.5 times more accessible surface area than EG films. Assemblies of streptavidin–latex beads generate p-SPR responses on both NPG and EG films that correlate well with the bead density obtained from scanning electron microscopy (SEM) images. A layer-by-layer assembly experiment on NPG involving biotinylated anti-avidin IgG and avidin, studied by l-SPR and SEM, shows that the l-SPR signal is directly linked to the accessibility of the interior of the NPG porosity, an adjustable experimental parameter that can be set by the dealloying condition and time

General preparation for Pt-based alloy nanoporous nanoparticles as potential nanocatalysts

Although Raney nickel made by dealloying has been used as a heterogeneous catalyst in a variety of organic syntheses for more than 80 years, only recently scientists have begun to realize that dealloying can generate nanoporous alloys with extraordinary structural characteristics. Herein, we achieved successful synthesis of a variety of monodisperse alloy nanoporous nanoparticles via a facile chemical dealloying process using nanocrystalline alloys as precursors. The as-prepared alloy nanoporous nanoparticles with large surface area and small pores show superior catalytic properties compared with alloyed nanoparticles. It is believed that these novel alloy nanoporous nanoparticles would open up new opportunities for catalytic applications

ALD Functionalized Nanoporous Gold: Thermal Stability, Mechanical Properties, and Catalytic Activity

Nanoporous metals have many technologically promising applications but their tendency to coarsen limits their long-term stability and excludes high temperature applications. Here, we demonstrate that atomic layer deposition (ALD) can be used to stabilize and functionalize nanoporous metals. Specifically, we studied the effect of nanometer-thick alumina and titania ALD films on thermal stability, mechanical properties, and catalytic activity of nanoporous gold (np-Au). Our results demonstrate that even only one-nm-thick oxide films can stabilize the nanoscale morphology of np-Au up to 1000 C, while simultaneously making the material stronger and stiffer. The catalytic activity of np-Au can be drastically increased by TiO{sub 2} ALD coatings. Our results open the door to high temperature sensor, actuator, and catalysis applications and functionalized electrodes for energy storage and harvesting applications