Description du sujet de thèse

High Entropy Alloys (HEAs) represent a class of metal alloys distinguished by their unique composition, comprising five or more elements in nearly equimolar ratios. These alloys have shown remarkable performances in various domains. Recent attention has shifted towards nanoscale HEAs (nano-HEAs), due to their exceptional structural and chemical properties, particularly in catalytic applications. However, the complex composition of nano-HEAs, responsible for their remarkable properties, also implies a complex landscape to fundamentally understand the origin of the catalytic performances.
The team just started a pioneering project to capitalize on the recent advances regarding catalytic properties of nano-HEAs, with the following objectives:
1. Developing a continuous flow synthesis method for the production of nano-HEAs.
2. Evaluating the catalytic performance of nano-HEAs in the CO2 methanation reaction.
3. Perform operando investigation using state-of-the-art experimental techniques to link structural and chemical properties of the nano-HEA to their catalytic properties.
Nano-HEAs have demonstrated potential as heterogeneous catalysts, particularly in the CO2 methanation reaction — a key process in Power-to-Gas technology which aims at providing long term storage for hydrogen applications. Despite facing challenges such as kinetics and stability, nano-HEAs exhibit enhanced activity, selectivity, and stability compared to traditional catalysts. Our research aims to overcome existing hurdles in nano-HEA synthesis and characterization. We seek to develop rational synthesis methods that offer reproducible control over NP composition, size, and distribution. Additionally, we aim to qualify and quantify the nature of nano-HEAs at the nanoscale, employing advanced electron microscopy and spectroscopy techniques. Finally, the catalysts will be probed in operating condition (operando) using X-ray absorption spectroscopy and X-ray diffraction on particle accelerators using synchrotron radiation.
This project presents an opportunity tailored for a student seeking comprehensive training in physico-chemistry, complete with exposure to cutting-edge experimental developments and apparatus. The candidate should possess a solid understanding of physicochemistry principles, and an appeal for hands-on experimentation.

Contexte de travail

PhD co-supervised with laboratory Matériaux et Phénomènes Quantiques at Université Paris Cité.