Wet-Chemical Synthesis of Porous Multifaceted Platinum Nanoparticles for Oxygen Reduction and Methanol Oxidation Reactions

Abstract

Herein, we report a facile and flexible synthesis of porous and highly faceted platinum nanoparticles (NPs) performed in the liquid phase. The synthesis is performed by reduction of platinum 2,4-pentantedionate in the presence of oleylamine and oleic acid in dibenzyl ether at 200 °C. The growth process was monitored by time-course transmission electron microscopy (TEM), revealing a peculiar progressive evolution that, in comparison with previous methodologies, is quite unusual. In fact, the morphology evolves first through nanocubes, nanostars, and dendrites to arrive at porous multifaceted NPs. This offers the possibility to selectively obtain materials with different degrees of complexity at a different time of reaction with one synthetic approach. Moreover, fine tuning of the reaction conditions was achieved by assessing, in dedicated experiments, the effects of temperature, surfactant concentration, and surfactant ratio, allowing control on NPs' dispersity and shape reproducibility. The dimensionally monodispersed NPs have a mean diameter of 52 ± 2 nm and display small regular crystallites with uniform facets exposed on the surface as evinced by high-resolution-TEM analysis. The as-prepared multifaceted platinum NPs were tested for oxygen reduction and methanol oxidation reactions exhibiting improved catalytic activity with respect to conventional Pt-based nanomaterials.