Seminar/Séminaire ICMN : Jeudi 28 Sept 2023 – 15h00 Bibliothèque de l’ICMN, CNRS, Orléans
Fahes, Abeer
Postdoctoral Researcher
ICMN – Interfaces, Confinement, Matériaux et Nanostructures
Université d’Orléans, CNRS
1B, rue de la Férollerie, 45100 Orléans
Title: Large-area Nanosensors Based on Self-assembled Ag/Au Bimetallic Nanostructures
Summary:
The hybrid bimetallic systems, which consist of two metallic nanostructures, have been recognized as a sustainable technology due to their ability to enhance, renovate, and enrich the properties of their integrated components. Plasmonic bimetallic nanoparticles (BNPs) synthesized through solution-based chemical synthesis with different morphologies have received significant attention and are the most widely used. However, to stabilize these BNPs at the nanoscale, they must undergo several steps and chemical treatments, such as surfactants to compensate for their surface energy. Despite their widespread use in various applications, there is still a need for a low-cost, scalable, and straightforward alternative. To date, no approach has been developed for directly synthesizing BNPs substrates on surfaces by self-assembly of polymers with precise control over structural properties.
In this regard, the authors have developed a reproducible and well-controlled strategy based on polymer-mediated self-assembly (Fahes et al., 2021; Omar et al., 2020). The nanofabrication method, called vapor-induced phase separation (VIPS), self-assembles silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) in a poly (methyl methacrylate, PMMA) thin layer on a silicon (N-doped) substrate (Fahes et al., 2022; Fahes et al., 2023). The Mn+/PMMA dispersion combined with the silicon substrate serves as a reducing agent, surfactant, and structure-directing agent. The experimental parameters of the synthetic approach were precisely optimized to achieve the desired materials. Despite the complexity of the synthetic approach, where studying the particle growth process presents challenges due to the interplay of numerous components (such as the Si substrate, PMMA, counter ions, Ag+, and Au3+) that can either collaborate or contend with each other, the authors performed an in-depth study to understand the physico-chemical mechanism of synthesis using optical measurements by micro-extinction setup. Surface-enhanced Raman scattering (SERS) measurements were then performed to assess the sensitivity of the samples as sensors. Ultimately, this work has opened up new possibilities for creating hybrid nanomaterials of controllable geometries over a large area for applications in SERS detection.
