Nanoporous gold (NPG) films are three-dimensional gold (Au) frameworks characterized by a uniform distribution of nanoscale irregular pores. Typically produced via a dealloying process, where the less noble silver (Ag) is selectively etched out, NPG films offer a large surface area, excellent chemical stability, remarkable catalytic activity, unique optical properties, and biocompatibility. These attributes make them invaluable for applications in catalysis, plasmonics, biosensors, and nanophotonics. However, the presence of residual Ag from the dealloying process can limit their performance in certain applications. In this study, we report a novel method for the fabrication of ultrapure, large-area NPG films (several cm²) using a light-induced and liquid crystal-templated method. A hexagonal lyotropic liquid crystal containing a strong acid and a nonionic surfactant is combined with an aqueous solution of HAuCl₄, followed by the photochemical synthesis of gold nanoparticles (NPs) within the liquid crystal. After calcination of the Au NP-containing liquid crystal film at high temperature, pure NPG films are produced. We demonstrate surface-enhanced Raman spectroscopy (SERS) of Rhodamine 6G (R6G) molecules adsorbed on the NPG films and detect extremely low concentrations (below 10^–6 M) of R6G. Additionally, we thoroughly investigated the formation and optical properties of the NPG films. The results reveal that the ultrapure NPG films contain high-density plasmonic nanocavities, where substantial electromagnetic fields are generated, leading to significant enhancement of optical processes at nanoscale dimensions.

中文翻译：

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具有高密度等离激元腔的大面积纯纳米多孔金薄膜的光诱导液晶模板制备


纳米多孔金 （NPG） 薄膜是三维金 （Au） 框架，其特征是纳米级不规则孔的均匀分布。NPG 薄膜通常通过脱合金工艺生产，其中选择性蚀刻出不太稀有的银 （Ag），具有较大的表面积、优异的化学稳定性、卓越的催化活性、独特的光学特性和生物相容性。这些特性使它们在催化、等离子体、生物传感器和纳米光子学中的应用中具有不可估量的价值。然而，脱合金过程中残留的 Ag 会限制它们在某些应用中的性能。在这项研究中，我们报道了一种使用光诱导和液晶模板化方法制造超纯、大面积 NPG 薄膜（几厘米²）的新方法。将含有强酸和非离子表面活性剂的六方溶致液晶与 HAuCl₄ 水溶液结合，然后在液晶内进行金纳米颗粒 （NP） 的光化学合成。含 Au NP 的液晶膜在高温下煅烧后，产生纯 NPG 薄膜。我们展示了吸附在 NPG 膜上的罗丹明 6G （R6G） 分子的表面增强拉曼光谱 （SERS），并检测极低浓度（低于 ^10-6 M）的 R6G。此外，我们彻底研究了 NPG 薄膜的形成和光学特性。结果表明，超纯 NPG 薄膜包含高密度等离子体纳米腔，其中会产生大量的电磁场，从而显着增强纳米级尺寸的光学过程。