Krishnan Siva Kumar, Esparza Rodrigo, Flores-Ruiz F J, Padilla-Ortega Erika, Luna-Bárcenas Gabriel, Sanchez Isaac C, Pal Umapada
CONACYT-Instituto de Física and Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Postal J-48, Puebla 72570, Mexico.
Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Santiago de Querétaro, Querétaro 76230, Mexico.
ACS Omega. 2018 Oct 4;3(10):12600-12608. doi: 10.1021/acsomega.8b02333. eCollection 2018 Oct 31.
Bimetallic Ag@Au nanoparticles (NPs) have received significant research interest because of their unique optical properties and molecular sensing ability through surface-enhanced Raman scattering (SERS). However, the synthesis of Ag@Au core-shell plasmonic nanostructures with precisely controlled size and shape remained a great challenge. Here, we report a simple approach for the synthesis of bimetallic Ag@Au nanodisks of about 13.5 nm thickness and different diameters through a seed-mediated growth process. The synthesis involves the conformal deposition of Au atoms at the corner sites of Ag nanoplate (AgNPL) seeds coupled with site-selective oxidative etching of AgNPL edges to generate Ag@Au nanodisks. The resultant Ag@Au nanodisks manifest significantly improved chemical stability and tunable localized surface plasmon resonance from the visible to the near-infrared spectral range. Moreover, in comparison to AgNPLs, the Ag@Au nanodisks showed greatly enhanced SERS performance with an enhancement factor up to 0.47 × 10, which is nearly 3-fold higher than that of the original AgNPLs (0.18 × 10). Furthermore, the Ag@Au nanodisks show a high sensitivity for detecting probe molecules such as crystal violet of concentration as low as 10 M and excellent reproducibility, with the SERS intensity fluctuation less than 12.5%. The synthesis route adapted for the controlled fabrication of Ag@Au nanodisks can be a potential platform for maneuvering other bimetallic plasmonic nanostructures useful for plasmonics and sensing applications.
双金属银@金纳米颗粒（NPs）因其独特的光学性质以及通过表面增强拉曼散射（SERS）的分子传感能力而受到了广泛的研究关注。然而，精确控制尺寸和形状的银@金核壳等离子体纳米结构的合成仍然是一个巨大的挑战。在此，我们报道了一种简单的方法，通过种子介导的生长过程合成厚度约为13.5 nm、直径不同的双金属银@金纳米盘。该合成方法包括在银纳米片（AgNPL）种子的边角位置共形沉积金原子，同时对AgNPL边缘进行位点选择性氧化蚀刻以生成银@金纳米盘。所得的银@金纳米盘表现出显著提高的化学稳定性以及从可见光到近红外光谱范围可调的局域表面等离子体共振。此外，与AgNPL相比，银@金纳米盘表现出大大增强的SERS性能，增强因子高达0.47×10，几乎是原始AgNPL（0.18×10）的3倍。此外，银@金纳米盘对检测浓度低至10 M的探针分子如结晶紫具有高灵敏度和出色的重现性，SERS强度波动小于12.5%。适用于可控制备银@金纳米盘的合成路线可能成为操控其他用于等离子体和传感应用的双金属等离子体纳米结构的潜在平台。
