Monitoring the restructuring of bimetallic nanoparticles under reactive atmosphere by in situ experiments
by: Julien Ramade, Emat
For several decades, bimetallic nanoparticles (NPs), also called nanoalloys, have been the subject of unceasing investigation as they combine specific characteristics of the matter at the nanoscale with interesting properties of alloys as compared to their constituents. Such a combination can induce remarkable physical and chemical properties far different from their bulk counterpart, thereby leading to various applications in optics, magnetism or catalysis.
In addition to size and shape effects, the relative composition of both species as the chemical arrangement are supplemental parameters allowing the tailoring of novel properties that may develop in such systems. However, their (chemical, geometric, electronic) structure may evolve under specific environments, especially for reactive materials when they are exposed to oxidizing or reducing atmospheres. It is thus crucial to develop characterization tools allowing to monitor the structural evolution of these NPs in order to understand the involved restructuring mechanisms under realistic application environments.
In this communication, I will present the study of the structural evolution of physically prepared silver-based Ag/M (M= In or Fe) NPs under controlled oxidizing and reducing atmospheres. A home-made environmental spectroscopic setup based on spatial modulation was developed to probe in situ the structure of NP assemblies through the study of their Localized Surface Plasmon Resonance (LSPR). This global (statistic) approach was coupled to a single NP approach by Environmental Transmission Electron Microscopy (E-TEM), leading to a deeper understanding of the restructuring mechanisms occurring in NPs under reactive environments.