Nanoporous Gold Nanoframes with Minimalistic Architectures: Lower Porosity Generates Stronger Surface-Enhanced Raman Scattering Capabilities

Abstract

Current synthesis of gold nanoframes has only demonstrated morphological control over wall thickness and wall length. Here, we demonstrate the ability to control the nanoscale porosity of these nanoframes, using a templated seed-mediated approach. The porosity on these nanoporous gold nanoframes (NGNs) is tuned by controlling the crystallite size of Au nanoparticles deposited on the AgCl templates. The yield of the NGNs approaches 100%. Despite its minimalist architectural construction, the NGNs are mechanically robust, retaining its morphology even after multiple centrifugation and sonication rounds. We further highlight that decreasing the porosity on the NGN leads to improved surface-enhanced Raman scattering (SERS) enhancement. Increasing the constituent Au crystallite size decreases the porosity, but increases the surface roughness of NGN, hence leading to greater SERS enhancement. The introduction of porosity in a gold nanoframe structure through our synthesis method is novel and generic, suggesting the extendibility of our method to other types of templates.

Metal Nanoparticles‐Enhanced Biosensors: Synthesis, Design and Applications in Fluorescence Enhancement and Surface‐enhanced Raman Scattering

“…[69] f) (i) Synthesis of AuAg nanoboxes using AgCl as the sacrificial template and etching agent. (ii) TEM images show the formation of thinner/porous AuAg nanoboxes by increasing the galvanic replacement time [74] . the successful synthesis of triangular Ag nanoplates (Figure 3e, bottom).…”

“…The first approach is based on the use of a sacrificial template such as AgCl for the growth/deposition of gold atoms on it, followed by removing the template using etchant such as ammonium hydroxide (NH 4 OH) (Figure 3f (i)). [74] The second approach is based on the galvanic replacement of Ag atoms by Au atoms. The synthesis of Au nanoframes using this approach usually starts from synthesis of a silver nanostructure (i. e., nanocube or other polyhedral nanostructures) followed by purification and addition of Au precursor for galvanic replacement reaction.…”

“…The synthesis of Au nanoframes using this approach usually starts from synthesis of a silver nanostructure (i. e., nanocube or other polyhedral nanostructures) followed by purification and addition of Au precursor for galvanic replacement reaction. It was found that more replacement of Ag atoms by Au atoms results in thinner frames with higher porosity (Figure 3f (ii)) [74] and tunable optical properties. [84] Interestingly, Au nanoframes of different morphology can be obtained by using different Ag nanostructures as the starting seeds.…”

Structurally and Compositionally Tunable Absorption Properties of AgCl@AgAu Nanocatalysts for Plasmonic Photocatalytic Degradation of Environmental Pollutants

“…As a result, AgCl nanomaterials with various shapes such as plate, cubic, spherical, and octahedral could be synthesized [5][6][7][8][9][10]. In addition to pure AgCl, composite nanostructures composed of AgCl and noble metals have recently been synthesized [5,6,[11][12][13]. However, most of the composite nanostructures were still compositionally limited to Ag/AgCl, whose sizes and shapes, and corresponding chemical and physical properties, were hardly controlled [14][15][16][17].…”

Structure and Applications of Gold in Nanoporous Form

“…The template-based strategy is the most common as wide varieties of desired structures can be created. Silver chloride (AgCl) can be used as a sacrificial template to prepare different types of zero-dimensional np-Au nanostructures, such as nanoframes, bowls and shells [14,15,22], Figure 2A and B. This solution phase synthetic strategy of np-Au can be performed by depositing Au nanoparticles from HAuCl 4 precursor on to AgCl template using hydroquinone as a reducing agent and polyvinyl pyrrolidone (PVP) as a stabilizing agent.…”