Solidification-Inspired Insight into the Formation Mechanism of Dendritic Nanostructures in Wet-Chemistry Synthesis

In this study, the formation mechanism of dendritic platinum (Pt) nanostructures synthesized via a wet-chemistry method is explored by drawing inspiration from solidification theory. A rational mechanism integrating experimental observations with solidification principles is proposed to explain the growth and evolution of the Pt nanodendrites. The synthesis is carried out by reducing K 2 PtCl 6 in oleylamine, yielding Pt nanodendrites with well-defined structures. The microscopic characterizations reveal that the nanodendrites consist of multiple arms extending from a central body, with growth along the ⟨111⟩ direction of face-centered cubic Pt. The formation process involves nucleation triggered by concentration fluctuations, followed by the growth of primary arms and subsequent secondary, tertiary branches as a result of supersaturation gradients in the solution. This solidification-inspired mechanism differs from traditional models like diffusion-limited aggregation, facet-selective capping, or oriented attachment and is validated through control experiments with other metals. Additionally, the dendritic Pt nanostructures exhibit enhanced electrocatalytic activity and durability in methanol oxidation reaction compared to commercial Pt/C catalyst, highlighting their potential in electrocatalysis. This work not only provides deep insights into the formation of dendritic nanostructures but also paves the way for designing efficient nanocatalysts.