Fig. 2: Atom probe tomography.
From: Isolated copper–tin atomic interfaces tuning electrocatalytic CO2 conversion
a SEM side view (54° tilted) of the needle-shape specimen. b 3D tomography of the Cu97Sn3 nanoparticle demonstrates the position relationship of Sn dopants (green) and Cu matrix (purple). c Sn iso-surface of 0.63 wt.% indicates the low dopant concentration region on the Cu nanoparticle, in contrast to (d) the Sn-rich region evidenced by the 3.53 wt.% Sn iso-surface. The z-direction of tomography corresponds to the tip axial direction. e A proxigram profile was in accordance with 3.53 wt.% Sn iso-surface, demonstrating the Sn composition reduces along the arrow direction in (d). f Frequency distribution analysis confirms a non-random distribution of Sn dopants. g The Sn concentration 2D contour projected on xy plane indicates a curved Sn-rich band, which corresponds to the Cu particle surface, and the low dopant region refers to the inside of the Cu particle.
