The advent of the new 4th generation x-ray light sources represents an unprecedented opportunity to conduct in situ and operando studies on the structure of nanoparticles in reactive liquid or gas environments. In this talk, we will illustrate how Bragg coherent x-ray imaging 1 allows to image in three dimensions (3D) and at the nanoscale the strain and defect dynamics inside nanoparticles as well as their refaceting during catalytic reactions 2–4. As an example, we successfully mapped the lattice displacement and strain of a Pt nanoparticle in electrochemical environment 5 (see Figure 1) and under CO reaction 3,4. Our results reveal that the strain is heterogeneously distributed between highly- and weakly-coordinated surface atoms, and propagates from the surface to the bulk of the Pt nanoparticle as (bi)sulphates anions adsorb on the surface 5. We will also discuss the possibility to measure particles as small as 20 nm 6 and to enable high-resolution and high-energy imaging with Bragg coherent x-ray diffraction at 4th generation x-ray light sources 7. Finally, we will highlight the potential of machine learning to predict characteristic structural features in nanocrystals just from their 3D Bragg coherent diffraction patterns 7. We acknowledge funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 818823). References: 1 I. Robinson et al., Coherent X-Ray Diffraction Imaging of Strain at the Nanoscale, Nat. Mater. 8, 291 (2009).2 J. Carnis, et al., Facet-Dependent Strain Determination in Electrochemically Synthetized Platinum Model Catalytic Nanoparticles, Small Weinh. Bergstr. Ger. e2007702 (2021).3 J. Carnis et al., Twin Boundary Migration in an Individual Platinum Nanocrystal during Catalytic CO Oxidation, Nat. Commun. 12, 5385 (2021).4 M. Dupraz et al., Imaging the Facet Surface Strain State of Supported Multi-Faceted Pt Nanoparticles during Reaction, Nat. Commun. 13, 1 (2022).5 C. Atlan et al., Imaging the Strain Evolution of a Platinum Nanoparticle under Electrochemical Control, Nat. Mater. 22, 6 (2023).6 M.-I. Richard et al., Bragg Coherent Diffraction Imaging of Single 20 Nm Pt Particles at the ID01-EBS Beamline of ESRF, J. Appl. Crystallogr. 55, 621 (2022).7 M.-I. Richard et al., Taking Bragg Coherent Diffraction Imaging to Higher Energies at Fourth Generation Synchrotrons: Nanoscale Characterization, ACS Appl. Nano Mater. 6, 10246 (2023).8 B. Lim et al., A Convolutional Neural Network for Defect Classification in Bragg Coherent X-Ray Diffraction, Npj Comput. Mater. 7, 1 (2021).
Richard et al. (Wed,) studied this question.