Aqueous-Phase Synthesis of Single-Crystal Pd Seeds 3nm in Diameter and Their Use for the Growth of Pd Nanocrystals with Different Shapes

This article describes an aqueous method for the synthesis of Pd seeds with a single-crystal structure and a uniform diameter of 3nm and their use for the growth of Pd nanocrystals with a variety of shapes. We have also investigated the effects of a number of parameters, including the temperature, reducing power of the reductant, and capping agent on the reduction rate of a Pd precursor, and thus the final size, size distribution, and morphology of the Pd seeds. By taking advantage of the coordination effect of Br ions with Pd2+ ions and their selective adsorption on the Pd(100) surface, Pd nanocrystals with a number of distinct shapes could be conveniently produced by varying the concentration of KBr added into the growth solution. This work provides a general and facile method for the green synthesis of Pd nanocrystals with controlled shapes, especially for the preparation of Pd nanocrystals with sizes in the sub-10nm regime.