Fig. 1: Experimentally determined 3D atomic structures of representative PtNi and Ga-PtNi nanoparticles during potential cycles and geometric characterization. | Nature Communications

Fig. 1: Experimentally determined 3D atomic structures of representative PtNi and Ga-PtNi nanoparticles during potential cycles and geometric characterization.

From: Atomic-scale 3D structural dynamics and functional degradation of Pt alloy nanocatalysts during the oxygen reduction reaction

Fig. 1

a–f Overall 3D atomic structure of different PtNi [pristine (a) and 12k (b)] and Ga-PtNi [pristine (c), 4k (d), 8k (e), and 12k (f)] nanoparticles after the indicated number of potential cycles. g–l, 3D atomic structures after a 180-degree rotation along the [001] axis from those in (a–f), with one octant of the nanoparticles removed to reveal the internal atomic structure. Each image in (g–l) corresponds to the images in the first row (a–f). m–r 1 Å thick internal slices at the center of the 3D tomograms perpendicular to the [001] direction. The intensity is shown in grayscale (linearly scaled and offset-adjusted to optimize contrast between Pt and Ni atoms), with the atomic coordinates of Pt and Ni marked by blue and red dots, respectively. Concave {111} facets (marked with white lines) are observed in the Ga-PtNi nanoparticle after 12k cycles (r). Scale bar, 2 nm. Each image in (m–r) corresponds to the images in the first row (a–f). Note that, the representative nanoparticles shown in (a–r) are PtNi-pristine-p2 (a, g, m), PtNi-12k-p1 (b, h, n), Ga-PtNi-pristine-p1 (c, i, o), Ga-PtNi-4k-p1 (d, j, p), Ga-PtNi-8k-p2 (e, k, q), and Ga-PtNi-12k-p2 (f, l, r) (Supplementary Tables 1 and 2). s Sphericity of the PtNi and Ga-PtNi nanoparticles during the potential cycles. The sphericity values of the ideal sphere, truncated octahedron, and octahedron are marked by dotted lines. t–v Fraction of {111} (t), {100} (u), and {110} (v) facets during potential cycles. Note that the values and error bars for each cycle corresponding to (s–v) represent the averages and standard deviations obtained from 2 PtNi pristine, 3 Ga-PtNi pristine, 2 Ga-PtNi 4k, 2 Ga-PtNi 8k, and 2 Ga-PtNi 12k samples. We have only one particle for PtNi 12k, and the error bar cannot be defined in the same manner in this case. Source data for dot or line plots in this figure are provided as a Source Data file.

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