A Review of Recent Developments of Mesoporous Materials

Abstract

This personal account concerns novel recent discoveries in the area of mesoporous materials. Most of the papers discussed have been published within the last two to three years. A major emphasis of most of these papers is the synthesis of unique mesoporous materials by a variety of synthetic methods. Many of these articles focus on the control of the pore sizes and shapes of mesoporous materials. Synthetic methods of various types have been used for such control of porosity including soft templating, hard templating, nano-casting, electrochemical methods, surface functionalization, and trapping of species in pores. The types of mesoporous materials range from carbon materials, metal oxides, metal sulfides, metal nitrides, carbonitriles, metal organic frameworks (MOFs), and composite materials. The vast majority of recent publications have centered around biological applications with a majority dealing with drug delivery systems. Several other bio-based articles on mesoporous systems concern biomass conversion and biofuels, magnetic resonance imaging (MRI) studies, ultrasound therapy, enzyme immobilization, antigen targeting, biodegradation of inorganic materials, applications for improved digestion, and antitumor activity. Numerous nonbiological applications of mesoporous materials have been pursued recently. Some specific examples are photocatalysis, photo-electrocatalysis, lithium ion batteries, heterogeneous catalysis, extraction of metals, extraction of lanthanide and actinide species, chiral separations and catalysis, capturing and the mode of binding of carbon dioxide (CO ), optical devices, and magneto-optical devices. Of this latter class of applications, heterogeneous catalysis is predominant. Some of the types of catalytic reactions being pursued include hydrogen generation, selective oxidations, aminolysis, Suzuki coupling and other coupling reactions, oxygen reduction reactions (ORR), oxygen evolution reactions (OER), and bifunctional catalysis. For perspective, there have been over 40,000 articles on mesoporous materials published in the last 4 years and about 1388 reviews. By no means is this personal account thorough or all inclusive. One objective has been to choose a variety of articles of different types to obtain a flavor of the breadth of diversity involved in the area of mesoporous materials.

Biomolecule‐Assisted Synthesis of Hierarchical Multilayered Boehmite and Alumina Nanosheets for Enhanced Molybdenum Adsorption

“…Furthermore, non‐siliceous precursors are often thermally unstable during calcination. To date, mesoporous oxides with a controlled pore size and morphology have been synthesized by using both template‐free and template‐based methods . However, the fabrication of mesoporous oxides with controlled crystallinity, dimensionality, and unique multilayered structures is still challenging and this has prompted the need for the development of new synthetic strategies …”

“…Al 2 O 3 possesses several transitional phases (α, χ, η, δ, κ, θ, γ) and among these, the γ‐Al 2 O 3 phase is arguably the most important because of its wider utilization in chemical and biomedical industries relative to the other phases . Due to the strong dependence of the electronic structure, the chemical reactivity, and the surface energy of Al 2 O 3 on its morphology, many efforts have been carried out to develop nanosized Al 2 O 3 with a controlled size and morphology . In particular, mesoporous γ‐Al 2 O 3 materials with distinct morphology, such as nanospheres, flower‐like, urchin‐like, nanoflakes, nanosheets, and nanorolls have been fabricated by using both template‐free and template‐based methods.…”

“…To date, mesoporous oxides with ac ontrolledp ore size and morphology have been synthesized by using both template-free [7,8,35] and template-based methods. [3,36,37] However, the fabrication of mesoporouso xides with controlledc rystallinity, dimensionality,a nd unique multilayereds tructures is still challenging and this has prompted the need fort he development of new synthetic strategies. [38,39] In recenty ears, mesoporous alumina (Al 2 O 3 )h as gained increasinga ttention owing to its high surface area, high mechanical strength, and excellent thermals tability as well as its potentiala pplication in catalysis and adsorption.…”

“…[41] Due to the strong dependence of the electronic structure, the chemical reactivity, and the surfacee nergy of Al 2 O 3 on its morphology,m any efforts have been carried out to develop nanosized Al 2 O 3 with a controlled size and morphology. [36,42] In particular, mesoporous g-Al 2 O 3 materials with distinct morphology,s uch as nanospheres, [7] flower-like, [43,44] urchin-like, [45] nanoflakes, [46] nanosheets, [43] and nanorolls [47] have been fabricated by using both template-free and template-based methods. Despite some success, there is still as trong need for the development of new strategies for fabricating mesoporous Al 2 O 3 with controlled morphology,p ore size, and crystallinity.…”

Enhanced Electrocatalysis of the Oxygen Reduction Reaction Using Cobalt and Iron Porphyrin/Ionic Liquid Systems

“…However, their limitations in energy conversion systems are associated with their high economic cost. For this reason, extensive work has been done on the search for more efficient and cheaper catalysts, such as those free of precious metals, mesoporous materials, carbonous materials, azamacrocyclic complexes, to name a few.…”