Protocol for the Nanocasting Method: Preparation of Ordered Mesoporous Metal Oxides

Abstract

Ordered mesoporous transition metal oxides have attracted considerable research attention due to their unique properties and wide applications. The preparation of these materials has been reported in the literature using soft and hard templating pathways. Compared with soft templating, hard templating, namely, nanocasting, is advantageous for synthesizing rigid mesostructures with high crystallinity and has already been applied to numerous transition metal oxides such as Co₃O₄, NiO, Fe₂O₃, and Mn₃O₄. However, nanocasting is often complicated by the multiple steps involved: first, the preparation of ordered mesoporous silica as the hard template, then infiltration of the metal precursor into the pores, and finally, formation of the metal oxide and removal of the hard template. In this paper, we provide a complete protocol that covers the preparation of most widely used ordered mesoporous silica templates (MCM-41, KIT-6, SBA-15) and the nanocasting process for obtaining ordered mesoporous metal oxides, with emphasizing cobalt oxide as an example. Characterization of the products is presented, and the factors that can potentially affect the process are discussed

A general ligand-assisted self-assembly approach to crystalline mesoporous metal oxides

“…Various strategies have been used to synthesize mesoporous transition metal oxides. One promising route is the hard template approach, which employs mesoporous silica or carbon as a rigid template to introduce the desired mesoporous structure and removes the template by etching or calcination to finally obtain mesoporous transition metal oxides [9][10][11][12] . This approach can synthesize unique crystalline and ordered mesoporous metal oxides but still has some deficiencies.…”

Advanced Functional Carbons and Their Hybrid Nanoarchitectures towards Supercapacitor Applications

“…[38,57] Their approacho pens up the standard concept of hard-template synthesis and is still widely used. The corresponding pore structure depends on the templates.I n early 1980, Knox et al synthesized mesoporous carbon by utilizing spherical silica gel as the startingm aterial, which involved the preparation of silica gel, impregnationo ri nfiltration of the silica template with carbon precursors, cross-linking and carbonization of the precursors, and removal of the hard template.…”

Organic Polymers as Porogenic Structure Matrices for Mesoporous Alumina and Magnesia

“…By definition, mesopore widths range from 2 to 50 nm [5]. For metal oxides with uniform and ordered mesopores, a variety of synthesis methods have been established, mostly by utilization of porogens; said porogens may be supramolecular entities of amphiphilic species dispersed in liquid media ('soft templates' [6]) or solid structure matrices such as porous silica ('hard templates') in the so-called 'nanocasting' process [6][7][8][9].…”