A Simple Route to the Synthesis of Pt Nanobars and the Mechanistic Understanding of Symmetry Reduction

Noble-metal nanocrystals with anisotropic shapes have received increasing interest owing to their unique properties. Here, a facile route to the preparation of Pt nanobars with aspect ratios tunable up to 2.1 was reported by simply reducing a Pt-IV precursor in N,N-dimethylformamide (DMF) at 160 degrees C in the presence of poly(vinyl pyrrolidone) (PVP). In addition to its commonly observed roles as a solvent and a reductant, DMF could also decompose to generate CO, a capping agent capable of selectively passivating Pt{100} facets to promote the formation of nanobars. The size and aspect ratio of the nanobars could be tuned by varying the amount of Pt-IV precursor involved in the synthesis, as well as the concentration of PVP because of its dual roles as a stabilizer and a co-reductant. Our mechanistic study indicated that the anisotropic growth resulted from both particle coalescence and localized oxidative etching followed by preferential growth.

Automated summary

A facile route to prepare tunable aspect ratio Pt nanobars by reducing Pt-IV precursor in DMF has been reported, where DMF decomposes to generate CO capable of passivating Pt{100} facets to promote nanobar formation, and PVP plays dual roles in controlling the size and aspect ratio of the nanobars. Mechanistic study indicates that anisotropic growth is a result of particle coalescence, localized oxidative etching, and preferential growth.