The controlled synthesis of complex hollow nanostructures and prospective applications

Abstract

Functionality in nanoengineered materials has been usually explored on structural and chemical compositional aspects of matter that exist in such solid materials. It is well known that the absence of solid matter is also relevant and the existence of voids confined in the nanostructure of certain particles is no exception. Indeed, over the past decades, there has been great interest in exploring hollow nanostructured materials that besides the properties recognized in the dense particles also provide empty spaces, in the sense of condensed matter absence, as an additional functionality to be explored. As such, the chemical synthesis of hollow nanostructures has been driven not only for tailoring the size and shape of particles with well-defined chemical composition, but also to achieve control on the type of hollowness that characterize such materials. This review describes the state of the art on late developments concerning the chemical synthesis of hollow nanostructures, providing a number of examples of materials obtained by distinct strategies. It will be apparent by reading this progress report that the absence of solid matter determines the functionality of hollow nanomaterials for several technological applications.

Transformation of Stöber Silica Spheres to Hollow Nanocatalysts

“…Since the discoveries of their transforming methods, silica‐based hollow architectures and particularly hollow spheres have gained more and more attention over the past two decades. One important reason to select siliceous materials and especially silica spheres as a starting template for synthesizing hollow structures is that they can be prepared at a relatively low cost but with a high morphological uniformity and tunable particle size distribution with a large quantity . Apart from hollowness, other features of hollow structures derived from silica spheres include high loading capacity, large pore volumes, huge specific surface area, good chemical and thermal stability, low density, surface functionality, permeability, low toxicity and good compatibility with other materials, which are prominent properties desired for vast range of applications .…”

“…A desirable way to produce uniform hollow silica spheres or silica‐based hollow structures with gram‐scale production could be controllable post‐treatment of synthesized Stöber SiO 2 spheres . Transformation of Stöber SiO 2 spheres to hollow nanostructures normally can be achieved via a number of ways . Partial removal of silica core, complete removal of silica core, and chemical transformation of silica core approaches are considered as such.…”

“…On the other hand, spatial compartmentalization of various functions into HoMSs such as surface‐anchored catalytic moieties (e. g., metal or metal oxide nanoparticles as well as nanoclusters) or confined catalytic species in the pores of shell will create a multifunctional catalyst. Again, since the present minireview is limited in length and does not aim to cover all aspects of catalytic hollow nanostructures, readers are referred to the previous eloquently written reviews, in order to acquire a comprehensive insight on catalytic‐ and reactor‐type forms related to hollow nanostructures.…”

Solid‐Phase Synthesis Porous Organic Polymer as Precursor for Fe/Fe3C‐Embedded Hollow Nanoporous Carbon for Alkaline Oxygen Reduction Reaction

“…[9] Template-assisted synthesis strategy affords a controllable method for the preparation of materials with hollow structure. [10] However, many insufficiency are still existed. For the one hand, the hollow shell is formed by the high temperature pyrolysis of the reaction monomers, for which the yield is always low; and in the most cases, it is a mathematical stochastic combination of chemical elements.…”

Iron oxide and various metal oxide nanotubes engineered by one-pot double galvanic replacement based on reduction potential hierarchy of metal templates and ion precursors

“…9 Previously, metal oxide nanotubes were synthesized by techniques such as template-mediated and template-free methods which include hydrothermal reaction, and chemical etching method. 4,10 In the template-mediated method, posttreatment is necessary to remove templates. Thus, it adds complexity to the synthesis process, increases frequency of structural deformation, and introduces more impurities even aer undergoing a separation process for the removal of leover template in the sample.…”