Functional Mesoporous Silica Nanomaterials for Catalysis and Environmental Applications

Abstract

Silica materials are used in a wide range of applications such as catalysis, photocatalysis, CO2 capture, and environmental remediation. These nanomaterials (NMs) have been extensively investigated since the advent of Stöber silica. However, the absence of pores and small surface area of Stöber silica limits its applications. Later, the discovery of MCM-41 type mesoporous silica using surfactants as structural directing agents became revolutionary in the field of silica NMs. This review focuses on the methods used for synthesizing mesoporous silica nanomaterials (NMs), especially mesoporous nanoparticles (NPs), and their applications in various fields including catalysis (i.e., support for nanoparticle catalysts) and environmental remediation (CO to CO2 conversion, volatile organic compound (VOC) removal, and CO2 capture). The current issues/challenges in realizing the practical applications of these conventional materials are also highlighted. This review also compares the characteristics and applications of MCM-41, SBA-15, and KCC-1 to demonstrate the effect of the morphology and pore architecture of silica on the properties of silica-based NMs. The scope for future developments in the synthesis and applications of silica materials with different pore sizes and morphologies is discussed.

Preparation of microporous glass fiber cloth without cracking

“…Elemental analyses were conducted using a wavelength-dispersive X-ray fluorescence spectrometer (Rigaku ZSX). The solid-state 29 Si and 1 H NMR spectra were recorded on a JEOL JNM CMX-400 spectrometer at 79.42 and 399.78 MHz, respectively. The solid-state 29 Si NMR spectra were obtained using the magic angle spinning (MAS) technique with a pulse delay of 60 s. The solid-state 29 Si NMR spectra were also obtained using cross-polarization (CP) and MAS techniques at a contact time of 5 ms.…”

“…The solid-state 29 Si and 1 H NMR spectra were recorded on a JEOL JNM CMX-400 spectrometer at 79.42 and 399.78 MHz, respectively. The solid-state 29 Si NMR spectra were obtained using the magic angle spinning (MAS) technique with a pulse delay of 60 s. The solid-state 29 Si NMR spectra were also obtained using cross-polarization (CP) and MAS techniques at a contact time of 5 ms. The solid-state 1 H NMR spectra were obtained using MAS technique with a pulse delay of 5 s. The samples were put into a 5-mm zirconia rotor with a spinning rate of 8 kHz.…”

“…The solid-state 1 H NMR spectra were obtained using MAS technique with a pulse delay of 5 s. The samples were put into a 5-mm zirconia rotor with a spinning rate of 8 kHz. The 29 Si and 1 H chemical shifts were externally referenced to polydimethylsiloxane at ¹33.8 ppm and hexamethylbenzene at 2.31 ppm, respectively. Prior to the measurements, samples were manually ground by a pestle and a mortar to form powders.…”

“…These procedures were mainly based on the obtained information in previous reports; the heat treatment of GFC at around its glass transition temperature with subsequent slow cooling canceled the structural differences between its fiber surfaces and inners, forming more homogenous and dense structures, which showed lower alkaline content dissolution than that of untreated GFC upon the acidic treatment of GFC. 15),16) Since the obtained microporous GFCs exhibit no crack generations and the GFC porosities are changed with the acid treatment time, the micropore formation mechanism is clearly discussed using 29 Si and 1 H nuclear magnetic resonance (NMR) spectroscopy.…”

Progress in Molecular Nanoarchitectonics and Materials Nanoarchitectonics

“…Energy-related applications to produce energy and manage energy are undoubtedly socially important issues in current science and technology [ 162 , 163 , 164 ] as well as environmental problems [ 165 , 166 , 167 ] accompanied with sensing [ 168 , 169 , 170 ] and remediation technologies [ 171 , 172 , 173 ]. Electrochemical and electrical charge storages and energy conversions with various catalysts including chemical catalysts [ 174 , 175 , 176 ], electrochemical catalysts [ 177 , 178 , 179 ], and photocatalysts [ 180 , 181 , 182 ] have important roles in the corresponding functions. In the most of approaches for these research targets, structural constructions with nanoscale components (nanoarchitectonics) are actually investigated to get better performances [ 183 , 184 ].…”