Reactivity of High Entropy NanoAlloys – REACTION

High Entropy NanoAlloys (HENAs) are nanomaterials composed of at least four metals that have the potential for applications related to their reactivity. To optimize their efficiency, it is therefore essential to identify and understand the restructuring mechanisms of HENAs when they are exposed to a reactive atmosphere, in order to optimize their structural features for specific applications. The aim of the REACTION project is to monitor in real time the structural and morphological modifications of HENA when exposed to reactive environments. To achieve this, we will use metallic nanostructures featuring Localized Surface Plasmon Resonance (LSPR), that is an optical property sensitive to the near environment, to probe the reactivity of HENA in their vicinity. The project is divided into several stages: first, the physical synthesis of a new class of heterostructures, in the form of core@shell nanoparticles, or more precisely "plasmonic metal"@HENA (MP@HENA). This will be carried out using the unique experimental setup built in the laboratory's, DIVA, ,which enables VAriable Incidence Deposition by electron beam evaporation or ion sputtering of metallic targets. These heterostructures will then be in situ characterized, in a controlled reactive environment, using a multi-scale approach in which their structure, morphology and organization will be reavaled by environmental TEM and synchrotron X-ray scattering, and their optical response will be measured in real time within a dedicated environmental cell developed in the laboratory. Beyond the possibility of monitoring HENA reactivity via LSPR, the combination of plasmonic material with HENA paves the way to other fields, such as plasmonic catalysis or the development of next-generation plasmonic sensors for molecules.