Toward a Quantitative Understanding of the Sulfate-Mediated Synthesis of Pd Decahedral Nanocrystals with High Conversion and Morphology Yields

We report a systematic study of the sulfate-mediated polyol synthesis of Pd decahedra in an attempt to maximize both the conversion and morphology yields. Quantitative analyses of the as-obtained products reveal the presence of nanocrystal populations with distinct ranges of size. Samples collected in the early stage of a standard synthesis indicate that this size distribution is likely caused by the coalescence of the initially formed decahedral nuclei. Kinetic measurements clearly show the impact of the sulfate additive on the initial reduction rate and thus the yield of decahedral nuclei. Based on the mechanistic understanding developed over the course of this work, we were able to significantly improve the conversion and morphology yields of the Pd decahedra synthesis by introducing a second reducing agent after the completion of homogeneous nucleation. The improvement in yields for the Pd decahedra synthesis will increase the availability of these nanocrystals as catalytic materials and as a unique platform for the development of more complex nanostructures.