Direct Observation of Three-Dimensional Atomic Structure of Twinned Metallic Nanoparticles and Their Catalytic Properties

Abstract

We determined a full 3D atomic structure of a dumbbell-shaped Pt nanoparticle formed by a coalescence of two nanoclusters using deep learning assisted atomic electron tomography. Formation of a double twin boundary was clearly observed at the interface, while substantial anisotropy and disorder were also found throughout the nanodumbbell. This suggests that the diffusion of interfacial atoms mainly governed the coalescence process, but other dynamic processes such as surface restructuring and plastic deformation were also involved. A full 3D strain tensor was clearly mapped, which allows direct calculation of the oxygen reduction reaction activity at the surface. Strong tensile strain was found at the protruded region of the nanodumbbell, which results in an improved catalytic activity on {100} facets. This work provides important clues regarding the coalescence mechanism and the relation between the atomic structure and catalytic property at the single-atom level.

Direct strain correlations at the single-atom level in three-dimensional core-shell interface structures

“…2f, g ). This not only emphasizes that atomic-scale tailoring of the local structural behavior is possible (controlling the in-plane displacement by tuning the radial strain, and vice versa), but also suggests that a simple unit cell volume-based description of surface strain 2 , 4 , 5 , 7 , 50 might not be sufficient to properly predict the surface catalytic activity, necessitating more detailed study incorporating the in-plane and out-of-plane strain behavior separately.…”

“…If two or more facets have the same smallest distance from the surface atom, we calculated the distance from the surface atom to all the atoms already assigned to one of the dominant facet families, and the surface atom was classified into the facet which contains the atom of the smallest distance. Therefore, all surface atoms are assigned to one of the three dominant facet families (unlike our previous approach 50 in which some surface atoms are excluded from ORR analysis). Next, the local volumetric strain for each surface atom was calculated as , where the is the bulk Pt lattice constant 41 3.91 Å and is the kernel averaged local lattice constant with the optimized Gaussian kernels (σ = 4.67 Å for Particle 1 and σ = 4.31 Å for Particle 2).…”

Recent Progress on Revealing 3D Structure of Electrocatalysts Using Advanced 3D Electron Tomography: A Mini Review

“…Similarly, Pelz et al applied AET to study the 3D atomistic structure of a multiply twinned Pd ( Pelz et al, 2022 ). Recently, Lee et al determined a full 3D atomic structure of a dumbbell-shaped Pt nanoparticle using deep learning assisted AET ( Lee, 2022 ). A 3D strain tensor mapping was obtained based on 3D reconstruction, where strong tensile strain at the protruded region of the nanodumbbell was confirmed and correlated to an improved oxygen reduction reactivity on {100} facets.…”

Single-Atom Level Determination of 3D Surface Atomic Structure via Neural Network-Assisted Atomic Electron Tomography

“…However, most of the surface characterization methods are either limited to 2D measurements or not reaching to true 3D atomic-scale resolution, and single-atom level determination of the 3D surface atomic structure for general 3D nanomaterials still remains elusive. Atomic electron tomography (AET) has been developed as a powerful tool to determine the 3D atomic structure of nanomaterials at the single-atom level [3][4][5][6][7][8]. However, often due to geometrical limitations, only part of a full tomographic angular range is experimentally measurable (so-called "missing wedge" problem), which results in elongation and Fourier ringing artifacts along the direction of the missing information in the reconstructed tomogram.…”