Critical role of reaction temperature for shaping bimetallic Pt-Co nanocrystals
Bibi Ruqia, Kyungsu Na and Sang-Il Choi
The shape or morphology of bimetallic alloy nanocrystals plays a substantial role in enhancement of many catalytic and electro-catalytic performances. However, various synthetic methods developed so far in controlling the shape of the bimetallic alloy nanocrystals are limited by the metal compositions and shape specificity. In this work, we report an experimental study for the critical role of reaction temperature on the shape-controlled synthesis of bimetallic Pt-Co nanocrystals. By varying the reaction temperature from 180 to 220°C, the resulting Pt-Co nanocrystals with different shapes such as concave cube, cube, and truncated cube were prepared. Transmission electron microscopy (TEM) image and selected area electron diffraction (SAED) pattern of the as-synthesized Pt-Co nanocrystals characterized monodispersed nanocrystals with good shape and size uniformities and their crystals structures. From the results, we found that the kinetic parameter, with respect to the ratio of deposition rate to surface diffusion rate of atoms (Vdepo/Vdiff), increased if the reaction temperature decreased. It is expected that this finding can help the understanding of the temperature effect on the formation and growth mechanism of bimetallic alloy nanocrystals.
Keywords: Bimetallic nanocrystals, platinum, cobalt, shape-controlled synthesis, concave cube, cube, truncated cube.