Nanoporous gold nanoparticles

Abstract

Nanoporous gold nanoparticles are fabricated by combining a thermal dewetting process of Au/Ag bilayer films and a dealloying process. As the gold concentration is small enough within the dewetted nanoparticles, a complete chemical removal of Ag can be achieved and there is a size shrinking during the dealloying process. The nanoporous gold nanoparticles possess a much higher surface-to-volume ratio than bulk nanoporous gold films or gold nanoparticles. The nanoporous nanoparticles have a potential usage in chemical, photonic, and catalytic applications.

Plasmonic nanosponges

“…For instance, Figure 1 shows the scanning electron microscopy (SEM) images of the gold nanosponges (nanoporous gold nanoparticles) which are formed via thermal annealing induced solid-state dewetting of Au/Ag bi-layers and a subsequent dealloying process [17]. Solid-state dewetting is a phenomenon of instability of thin metal films driven by reduction of surface energy.…”

“…By combining with other synthesis or nanofabrication methods including polyol process, templated process, solid-state dewetting, and different nanolithography techniques, Au-Ag alloys can be formed in many specific forms, and after dealloying, the nanoporous gold can be obtained in the corresponding forms, including the forms of nanotubes [38], nanowires [39], nanoparticles [17,40,41], hollowed nanospheres [42], nanobowls [43], nanodisks [44,45], ordered array of nanoparticles and nanodisks [46][47][48].…”

“…For instance, NPG can be fabricated in the form of nanoparticles or nanosponges after dealloying of Au-Ag alloy nanoparticles [17]. The optical and plasmonic properties (especially, the localized plasmon resonances) of the nanosponges are even more fascinating due to the distinct structural feature, in which both 3D character of the porous (percolated air/gold) structure and 0D character of nanoparticle form are well integrated and combined.…”

Nanoporous Gold Electrodes and Their Applications in Analytical Chemistry

“…In one example, nanoporous gold nanoparticles were made by first starting with an Au:Ag bilayer film deposited on a silicon substrate using electron beam evaporation. The bilayer film was dewetted by annealing at 900 ∘ C under argon to form the alloy nanoparticles [60]. Likewise, cosputtering a coating from separate Ag and Au targets is conducive toward making nanoporous gold films of various compositions and thicknesses on different substrates [23,38,51,61,62] and can also be coupled with optical lithography to form patterns of nanoporous gold on a substrate [63,64].…”

Fabrication of porous microrings via laser printing and ion-beam post-etching

“…Specifically, porous materials, nanostructures and nanoparticles, routinely reaching uniform SERS enhancement sufficient to overcome single-molecule detection limit independently on excitation/detection conditions, are of growing interest [24][25][26] . Several papers reported fabrication of such sponge-like structures, using dealloying of the two-component template via its dissolving in a corrosive environment 27,28 . Meanwhile, to design sensitive elements for advanced biosensors, along with desirable porosity, it is also important to control the overall size and shape of such porous templates as well as to arrange them into well-ordered arrays at specific point on a substrate with micrometer-scale lateral accuracy.…”