CoHerent diffrAction foR a Look Inside Nanostructures: catalysis and interfacE – CHARLINE

Heterogeneous catalysis of nanomaterials has emerged as an efficient way to speed up the catalytic process due to the higher surface area of nanoparticles compared to their bulk counterparts. A challenging issue is the development of heterogeneous catalysis with a high selectivity close to 100% as well as understanding the durability issues of catalysts. To tackle these problems, the CHARLINE young-scientist project proposes to develop new faster characterization systems and state-of-the-art in situ monitoring to optimize catalyst and reactor operations simultaneously. The ambition of the project is to study in situ and operando the structural evolution of catalytic nanoparticles in various gaseous and liquid environments during reaction by using the unique capabilities of coherent X-ray diffraction Bragg imaging (CDI). Recently, we have successfully performed first proof-of-concept experiments using Pt nanocrystals to show the feasility of the Bragg CDI approach under atmospheric air and gas conditions. As dedicated instruments have just reached user operation, it is only now that this new imaging technique can be applied during chemical reaction. Operando X-ray catalysis has often been carried out under idealized conditions and averaging information from macroscopic “facets”. This approach suffers from the lack of transferability to nanocrystalline systems, where the facets are assumed to change during each state of the reaction leading eventually to the much higher catalytic activity of nanocrystals. In situ and operando CDI is thus of highest priority and extremely timely as the technique can probe structural changes in individual nanocrystals and under conditions where up to now, no other technique could probe the relevant structural parameters. The project will shed light on most relevant industrial processes and will open new horizons in the field of heterogeneous catalysis by probing the structure of nanocatalysts using the unique capabilities of in situ and operando Bragg CDI. Ex situ local characterization tools, like atom probe tomography and transmission electron microscopy, will also be employed as complements to spatially resolve strain, segregation and/or composition at the atomic scale.