Mesocrystals from Platinum Nanocubes.

Christian Jenewein,Helmut Cölfen

doi:10.3390/nano11082122

Abstract

Platinum nanoparticles are widely known for their numerous electrochemical and catalytic applications. Enhanced or novel properties that may arise when ordering such particles in a highly defined manner, however, are still subject to ongoing research, as superstructure formation on the mesoscale is still a major challenge to be overcome. In this work, we therefore established a reproducible method to fabricate micrometer-sized superstructures from platinum nanocubes. Through small-angle X-ray scattering and electron diffraction methods we demonstrate that the obtained superstructures have a high degree of ordering up to the atomic scale and, therefore, fulfill all criteria of a mesocrystal. By changing the solvent and stabilizer in which the platinum nanocubes were dispersed, we were able to control the resulting crystal habit of the mesocrystals. Aside from mesocrystal fabrication, this method can be further utilized to purify nanoparticle dispersions by recrystallization with respect to narrowing down the particle size distribution and removing contaminations.

Highlights

The fabrication of novel nanostructured materials via nanoparticle aggregation and self-assembly has proven to be one of the most promising superstructure formation pathways in the last decade [1,2,3,4,5,6]
Besides particle size and shape, it has been observed that the stabilizer swelling, as well as the used solvents, might play a crucial role when it comes to particle self-organization [40]. To investigate if these observations are prevalent in other materials as well, we used platinum nanoparticles and modified the reported synthesis route in order to obtain various batches of platinum nanocubes coated with different stabilizers
The strong towards self-assembly of fatty-acid-stabilized platinum nanocubes nanocubes was utilized in this work to establish a gas-phase diffusion synthesis route to was utilized in this work to establish a gas-phase diffusion synthesis route to assemble assemble nanocubes into highly superstructures. These superstructures platinum platinum nanocubes into highly ordered. These superstructures in form in form of micrometer-sized crystals were subsequently identified as mesocrystals by the of micrometer-sized crystals were subsequently identified as mesocrystals by the means means of due to their long-range particle ordering on the atomic scale

Summary

Introduction

The fabrication of novel nanostructured materials via nanoparticle aggregation and self-assembly has proven to be one of the most promising superstructure formation pathways in the last decade [1,2,3,4,5,6]. The inherent particle-mediated nonclassical crystallization pathway of these processes has raised increasing scientific attention in more recent research [7,8,9,10,11,12,13,14]. Researchers have discovered that the behavior of a controlled aggregation and self-assembly can further be utilized to create astounding new materials with exciting properties [6,15,16,17,18,19]. Mesocrystals can serve as a model system when it comes to the investigation of nonclassical crystallization processes as a result of their particle-based nature [7,11,28,29]

Methods

Results

Conclusion