Monodisperse and Corrosion‐Resistant Metallic Nanoparticles Embedded into Sepiolite Particles for Optical and Magnetic Applications

Abstract

The preparation of large quantities of heterogeneous materials containing non-agglomerated and monodispersed nanoparticles is becoming one of the bottlenecks that hinders the development of commercial devices. Here we describe a method to prepare monodispersed metallic (Cu, Ag, Au, Ni, Co, and Fe) nanoparticles in a silicate matrix (sepiolite) by means of a reduction process of metallic cations associated with a dehydration process of the matrix. This process is characterized by the huge amount of monodispersed metallic nanoparticles that it produces. Additionally, these nanoparticles have been revealed to be remarkably stable against oxidation because the transformed sepiolite matrix becomes a diffusion barrier for oxygen. Furthermore, the nanoparticles present suitable properties to be used for optical and magnetic applications.

The role of magnesium on the stability of crystalline sepiolite structure

“…into the original octahedral positions. 10,19,20 In this regard, we have chosen the Ni 2+ cation because its water coordination sphere is very similar to that of Mg 2+ cations and Ni 2+ cations are more easily hydrolysed and consequently, it exhibits an adsorption pH lower than Mg 2+ cations:…”

“…into the octahedral vacancies, which after the subsequent thermal reduction process, may become metallic nanoparticles embedded in a silicate matrix. 10,11 In this sense, Ni 2+ cations have been incorporated to the sepiolite silicate framework after different leaching treatments in order to check the stability of the sepiolite crystalline structure, and therefore the size, morphology and the stability of the corresponding metallic nanoparticles in sepiolite. In this regard, different techniques (X-ray diffraction (XRD), IR, transmission electron microscopy (TEM), Brunauer-Emmet-Teller (BET) and ICP) were used to characterize the resulting materials.…”

Organic Modification of Hydroxylated Nanoparticles: Silica, Sepiolite, and Polysaccharides

“…Sepiolite can also be used as metal nanoparticle carrier [195,196]. Modified with alkylsilanes, these metal-sepiolites can be dispersed by industrially scalable extrusion process in polyethylene and polystyrene matrixes, conferring the composite with plasmonic or magnetical properties [197].…”

Defluidization and agglomeration of a fluidized bed reactor during Cynara cardunculus L. gasification using sepiolite as a bed material

“…[32]. It is usually employed in a wide variety of industries as industrial adsorbent, cosmetics, filtering, ceramics or paint due to its adsorbent properties, chemical and mechanical stability and high surface area (~300 m 2 /g) [32][33][34].…”