Artículos de revistas
X-ray studies bridge the molecular and macro length scales during the emergence of CoO assemblies
Fecha
2021-12-01Registro en:
Nature Communications, v. 12, n. 1, 2021.
2041-1723
10.1038/s41467-021-24557-z
2-s2.0-85111092520
Autor
Center for Hybrid Nanostructures
Deutsches Elektronen-Synchrotron DESY
Universidade Estadual Paulista (UNESP)
Faculty of Physics and Center for NanoScience (CeNS)
Faculty of Physics and Applied Computer Science
AGH University of Science and Technology
The Rossendorf Beamline at the European Synchrotron Radiation Facility ESRF
Institute of Resource Ecology
European Synchrotron Radiation Facility ESRF
The Hamburg Centre for Ultrafast Imaging
Institución
Resumen
The key to fabricating complex, hierarchical materials is the control of chemical reactions at various length scales. To this end, the classical model of nucleation and growth fails to provide sufficient information. Here, we illustrate how modern X-ray spectroscopic and scattering in situ studies bridge the molecular- and macro- length scales for assemblies of polyhedrally shaped CoO nanocrystals. Utilizing high energy-resolution fluorescence-detected X-ray absorption spectroscopy, we directly access the molecular level of the nanomaterial synthesis. We reveal that initially Co(acac)3 rapidly reduces to square-planar Co(acac)2 and coordinates to two solvent molecules. Combining atomic pair distribution functions and small-angle X-ray scattering we observe that, unlike a classical nucleation and growth mechanism, nuclei as small as 2 nm assemble into superstructures of 20 nm. The individual nanoparticles and assemblies continue growing at a similar pace. The final spherical assemblies are smaller than 100 nm, while the nanoparticles reach a size of 6 nm and adopt various polyhedral, edgy shapes. Our work thus provides a comprehensive perspective on the emergence of nano-assemblies in solution.