Nanoscale HEAs: Continuous Flow Synthesis & Catalytic Application – NAUSYCAA

High Entropy Alloys (HEAs) are metal alloys composed of five or more elements in nearly equimolar ratios, demonstrating remarkable properties in thermoelectric and magnetic domains. These properties result from a complex interplay of high entropy, lattice distortion, sluggish diffusion, and a cocktail effect. Recent interest has focused on HEA nanoparticles (NPs) due to their exceptional structural and chemical properties, especially as heterogeneous catalysts for thermal and electrocatalytic reactions. The origin of their superior catalytic performance is still debated, but their durability and resistance to harsh conditions make them promising catalysts.
One specific application of HEA NPs is in CO2 methanation, a key reaction in the Power-to-Gas technology, which aims to convert excess renewable energy into a chemical energy carrier. HEA NPs show potential in accelerating this reaction with high activity, selectivity, and stability, while avoiding costly metals. The exothermic nature of the methanation reaction aligns well with HEAs' advantages.
However, challenges must be addressed to fully utilize HEAs as catalysts. First, a rational and reproducible synthesis method for nano-HEAs is needed, allowing control over composition, size, and distribution under reasonable experimental conditions. Second, characterizing the alloys at the nanoscale is crucial to attribute any catalytic gains to HEA properties. In-situ and operando analysis during synthesis and catalytic reactions are key for identifying the active phase.
The NAUSYCAA project aims to (i) develop a continuous flow synthesis method for nano-HEAs, characterizing them with advanced techniques, and (ii) assess their catalytic performance in CO2 methanation. Operando experiments will link structural and chemical changes in the catalyst to the evolution of their catalytic performance.