Pursuing unprecedented anisotropic morphologies of halide-free Pd nanoparticles by tuning their nucleation and growth.

In this paper, a highly effective and scalable polyol-based modified procedure is reported, yielding shape-controlled Pd nanoparticles (NPs) formed two distinct growth mechanisms as a function of apparent pH. Starting from tetraethylammonium tetrahydroxypalladate (TEA)[Pd(OH)], a halide-free precursor, the resulting shape of the NPs ranged from highly defective worm-like nanostructures to well-defined polyhedra (tetrahedra, octahedra and 5-fold twins) as shown by TEM, HRTEM, and STEM. The effect of the different synthesis parameters was thoroughly investigated, finding that apparent pH - modulated by adding diluted HNO - is the key parameter in determining the final size and shape of Pd NPs, whose evolution was followed during the reaction.