uantitative Structural Analysis of AuAg Nanoparticles Using a Pair Distribution Function Based on Precession Electron Diffraction: Implications for Catalysi

Author(s)

Correa, Leonardo M. ^[1] ; Moreira, Murilo ^[1] ; Rodrigues, Varlei ^[1] ; Ugarte, Daniel ^[1]

Affiliation

^[1] Univ Estadual Campinas UNICAMP, Inst Fis Gleb Wataghin, BR-13083859 Campinas, SP - Brazil

• Document type: Journal article
• Source: ACS APPLIED NANO MATERIALS; v. 4, n. 11, p. 12541-12551, NOV 26 2021.
• Web of Science Citations: 0

Abstract

Nanostructured materials and nanoparticles (NPs) probably represent the most promising system to develop technological applications and devices. The atomic arrangement of nanosystems can be quite different from the corresponding bulk material; the access to reliable and quantitative structural characterization tools for this size regime is still an open issue. Transmission electron microscopy (TEM) results are many times qualitative and hardly fulfill the requirement for quantitative statistics. This is particularly critical for many nanocatalysts displaying polycrystalline agglomerated NPs with significant size dispersion. Herein, we report a method for structural refinement and quantitative analysis of nanomaterial atomic arrangement based on an electron pair distribution function (ePDF) derived from precession electron diffraction (PED) patterns. We have shown that a high-quality and reliable structural refinement, whose residue values (similar to 15%) are similar to synchrotron-based nanosystem studies, can be obtained from catalyst complex nanostructure samples using a low-profile LaB6-gun TEM. The mass of the sample used in our experiment is extremely small, below the picogram range, and the measurements required a total electron dose of similar to 10 e(-)/angstrom(2); this indicates that the ePDF displays a huge potentiality to analyze quantitatively beam-sensitive materials. Although a complex sample and sophisticated simulation, including size dispersion, the number of free fitting parameters was kept to a rather low value (only 3), guaranteeing that the low-residue values are realistic, accurate, and not an effect of overfitting. Our results show that a PED-based ePDF may provide a wealth of quantitative structural information for complex nanostructured materials as used in technological applications as supported catalysts. We anticipate that a PED-based PDF will become a reliable approach to analyze quantitatively the statistical properties of complex nanostructured samples, which are rather difficult to identify by 2D projection atomic resolution TEM images. (AU)

• FAPESP's process: 07/01722-9 - Development of a mass selected metallic nano-aggregate source
• Grantee: Varlei Rodrigues
• Support Opportunities: Regular Research Grants
• FAPESP's process: 14/01045-0 - Advanced electron microscopy studies of metallic clusters and nanocomposites materials for photovoltaic applications
• Grantee: Daniel Mario Ugarte
• Support Opportunities: Scholarships abroad - Research