Abstract
Nanoparticles hosted in conductive matrices are ubiquitous in electrochemical energy storage, catalysis and energetic devices. However, agglomeration and surface oxidation remain as two major challenges towards their ultimate utility, especially for highly reactive materials. Here we report uniformly distributed nanoparticles with diameters around 10 nm can be self-assembled within a reduced graphene oxide matrix in 10 ms. Microsized particles in reduced graphene oxide are Joule heated to high temperature (∼1,700 K) and rapidly quenched to preserve the resultant nano-architecture. A possible formation mechanism is that microsized particles melt under high temperature, are separated by defects in reduced graphene oxide and self-assemble into nanoparticles on cooling. The ultra-fast manufacturing approach can be applied to a wide range of materials, including aluminium, silicon, tin and so on. One unique application of this technique is the stabilization of aluminium nanoparticles in reduced graphene oxide film, which we demonstrate to have excellent performance as a switchable energetic material.
Highlights
Nanoparticles hosted in conductive matrices are ubiquitous in electrochemical energy storage, catalysis and energetic devices
The nanoparticleRGO films were fabricated with a homemade setup, where in situ monitoring of the temperature and electrical conductivity during Joule heating can be achieved (Fig. 2a)
To obtain the nanoparticle-reduced graphene oxide (RGO) structure, we started with microsized particles embedded within an RGO thin film prepared by vacuum filtration (Supplementary Fig. 1 and Supplementary Methods)
Summary
Nanoparticles hosted in conductive matrices are ubiquitous in electrochemical energy storage, catalysis and energetic devices. We report an ultra-fast (as fast as 2 ms) process to produce uniformly distributed nanoparticles in a conductive reduced graphene oxide (RGO) matrix by directly Joule heating a metal/ semiconductor-RGO film (Fig. 1a) to a high temperature (B1,700 K or higher). RGO sheets serve as a perfect host material for such unique high-temperature process, owing to their defect sites and high melting temperature (stable up to 3,300 K)[40,41,42,43,44,45] This high-temperature process for in situ synthesis of nanoparticles without agglomeration and surface oxidation is applicable to any materials with a lower melting point than 3,300 K. We demonstrate fast nanoparticle formation for aluminium (Al), silicon (Si), tin (Sn), gold (Au) and palladium (Pd) These materials in their nanoparticle form have been widely used in energetics, energy storage, optical, sensing and catalytic applications. We combined three-dimensional (3D) printing with this technique for both precise shape control and scalable manufacturing of nanoparticles-RGO architectures (Fig. 1c)
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