Mini Review: Electroanalytical Sensors of Mesoporous Silica Materials

Mesoporous silica materials are promising substrates for electroanalytical sensors and electrocatalysis. Their characteristics include uniform pore sizes, surface areas in excess of 1000 m² g^?1, and long-range ordering of the packing of pores. The size scale, aspect ratio, and properties of mesoporous silica provide advantages in a variety of sensor applications. To improve performance, miniaturize platforms, and expand applications for trace analysis, novel materials with high sensitivity and rapid response have been developed and employed in recent years. These materials include pure mesoporous silica, mesoporous silica functionalized with organic groups, and composite or hybrid mesoporous silica. In this review, recent advances are outlined involving the application of mesoporous silica-based materials in electroanalytical sensors.     

Mesoporous materials in sensing: morphology and functionality at the meso-interface

Mesoporous materials are finding increasing utility in sensing applications. These applications can benefit from a surface area that may exceed 1,000 m² g⁻¹ and fast diffusion of analytes through a porous structure. This article reviews recent developments in mesoporous materials-based sensing and provides examples of the impact of different surface functionality, pore structure, and macro-morphology in an attempt to illustrate the contribution of these factors to the selectivity and sensitivity of a sensor response. The materials discussed include ordered mesoporous silicates synthesized with surfactants, hard templated ordered mesoporous carbons, and metal oxides with porous textures which have been applied to advantage in various detection schemes. Chemical functionalization of mesoporous materials through silane grafting, co-condensation, and adsorption are also addressed.     

Mesoporous Materials‐Based Electrochemical Sensors

A review (350 references) is given to the interest of mesoporous materials for designing electrochemical sensors. After a brief summary of the implication of template‐based ordered mesoporous materials in electrochemical science, the various types of inorganic and organic‐inorganic hybrid mesostructures used to date in electroanalysis and the corresponding electrode configurations are described. The various sensor applications are then discussed on the basis of comprehensive tables and some representative illustrations. The main detection schemes developed in the field are (volt)amperometric sensing subsequent to preconcentration and electrocatalytic detection.     

A two-step route to synthesis of small-pored and thick-walled SBA-16-type mesoporous silica under mildly acidic conditions

Highly ordered SBA-16-type mesoporous silica materials were synthesized by using poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) triblock copolymer (EO(132)-PO(50)-EO(132), Pluronic F108) as template through a two-step pathway under mildly acidic conditions (pH 2.15-4.50). The highly ordered cage-like mesoporosity of the prepared SBA-16-type mesoporous silica materials having Im3m cubic mesostructure was proved by the well-defined X-ray diffraction patterns combined with transmission electron microscopy. Scanning electron microscopy shows a variation from the spherical agglomerations to the randomly shaped ones with an increase of pH value. The nitrogen adsorption-desorption analysis reveals that the prepared SBA-16-type mesoporous silica materials have a uniform small-sized pore diameter (3.37-4.24 nm) and very thick pore wall (8.84-10.2 nm). These features may make the SBA-16-type mesoporous silica materials synthesized in this study favor the incorporation of catalytically active heteroatoms in silica frameworks, and the functionalization of organic groups for applications in catalysis, sensor and separation. The two-step synthetic method under the mildly acidic conditions can also be extended to the production in the industrial scale as an environmentally friendly way.     

Two-dimensional mesoporous materials：From fragile coatings to flexible membranes

This paper reviews the progress of two-dimensional mesoporous materials including their synthesis strategy,mesostructure,composition,surface property,flexibility,and potential applications.During the past two decades,research on two-dimensional mesoporous materials has experienced an evolution from fragile coatings to flexible membranes.Aiming at practical applications,it is significant to support mesoporous materials with proper matrices for example porous membranes especially flexible ones to form mesoporous composite membranes with designed pore size and chemistry.     

Hydrothermally Stable and Catalytically Active Ordered Mesoporous Materials Assembled from Preformed Zeolite Nanoclusters

Microporous zeolites are widely used commercial catalysts, but their applications are intrinsically limited by their small channel diameters. Recent progress in solving this is used to ordered mesoporous materials such as MCM-41, HMS and SBA-15. These mesoporous materials have pore diameters of 30–60 Å and exhibit catalytic properties for the catalytic conversion of bulky reactants, but unfortunately, when compared with microporous zeolites, the catalytic activity and hydrothermal stability are relatively low, which severely hinders their practical applications. The relatively low catalytic activity and hydrothermal stability can be attributed to the amorphous nature of the mesoporous walls. We review here that the assembly of preformed zeolite precursors with surfactants can synthesize a series of ordered mesoporous materials, which include (1) strongly acidic and hydrothermally stable mesoporous aluminosilicates synthesized in alkaline media; (2) strongly acidic and hydrothermally stable mesoporous aluminosilicates synthesized in strongly acidic media; (3) hydrothermally stable mesoporous titanosilicates with catalytically active titanium species in oxidations; (4) hydrothermally stable mesoporous ferrisilicates. This work would open a door for the industrial application of mesoporous materials as catalysts for large molecules.     

Random‐Graft Polymer‐Directed Synthesis of Inorganic Mesostructures with Ultrathin Frameworks

A widely employed route for synthesizing mesostructured materials is the use of surfactant micelles or amphiphilic block copolymers as structure‐directing agents. A versatile synthesis method is described for mesostructured materials composed of ultrathin inorganic frameworks using amorphous linear‐chain polymers functionalized with a random distribution of side groups that can participate in inorganic crystallization. Tight binding of the side groups with inorganic species enforces strain in the polymer backbones, limiting the crystallization to the ultrathin micellar scale. This method is demonstrated for a variety of materials, such as hierarchically nanoporous zeolites, their aluminophosphate analogue, TiO₂ nanosheets of sub‐nanometer thickness, and mesoporous TiO₂, SnO₂, and ZrO₂. This polymer‐directed synthesis is expected to widen our accessibility to unexplored mesostructured materials in a simple and mass‐producible manner.     

有机-无机杂化氧化硅基介孔材料

有机基团可以通过嫁接或共聚的方法引入到氧化硅基介孔材料的孔表面或材料的骨架中,形成表面结合型和桥键型两大类有机-无机杂化氧化硅基介孔材料.本文综述了有机-无机杂化氧化硅基介孔材料的最新研究进展,介绍了其合成方法、应用及潜在的应用领域,详细总结了目前已报道的有机-无机杂化氧化硅基介孔材料的种类,展望了桥键型有机-无机杂化氧化硅基介孔材料的发展及应用前景.     

Ordered mesoporous materials at the beginning of the third millennium: new strategies to create hybrid and non-siliceous variants

In recent years, research efforts in the field of ordered mesoporous materials are shifting towards either hybrid materials, containing both inorganic (typically silica) and organic functionalities, or towards variants that do not contain silica at all. Promising examples of hybrid materials are periodic mesoporous organosilicas (PMOs); examples of non-siliceous mesoporous materials are carbons, polymers and metal oxides. They can be further tuned to obtain structures with a wide range of functional groups, and are candidates for applications in adsorption, catalysis, sensoring, microelectronics and several other applications.     

Synthesis, characterization, and electrochemical properties of ordered mesoporous carbons containing nickel oxide nanoparticles using sucrose and nickel acetate in a silica template

New ordered mesoporous carbons containing nickel oxide nanoparticles have been successfully synthesized by carbonization of sucrose in the presence of nickel acetate inside SBA-15 mesoporous silica template. The obtained samples were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, and transmission electron microscopy (TEM). The NiO nanoparticles were embedded inside the mesoporous carbon framework due to the simultaneous pyrolysis of nickel acetate during carbonization. The electrochemical testing of the as-made nanocomposites showed a large specific capacitance of 230 F g⁻¹ using 2 M KOH as the electrolyte at room temperature. This is attributed to the nanometer-sized NiO formed inside mesoporous carbons and the high surface area of the mesopores in which the NiO nanoparticles are formed. Furthermore, the synthetic process is proposed as a simple and general method for the preparation of new functionalized mesoporous carbon materials, for various applications in catalysis, sensor or advanced electrode material.     

Universal Access to Two-Dimensional Mesoporous Heterostructures by Micelle-Directed Interfacial Assembly

Two-dimensional (2D) mesoporous heterostructures combining ultrathin nanosheet morphology, periodic porous surface structures, and diverse hybrid compositions have become increasingly important for renewable energy storage and electronics. However, it remains a great challenge to develop a universal method to prepare 2D mesoporous heterostructures. Herein, we report a composite-micelle-directed interfacial assembly method to synthesize heterostructures of an ultrathin 2D material covered with mesoporous monolayers assembled on both sides. To demonstrate the concept, we first fabricated a new sandwichlike carbon@MXene@carbon mesoporous heterostructure through the self-assembly of exfoliated MXene nanosheets and block copolymer F127/melamine-formaldehyde resin composite micelles and subsequent thermal treatment. Finally, we demonstrate that the carbon@MXene@carbon mesoporous heterostructured nanosheets manifest remarkably enhanced electrochemical performance as a cathode material for lithium–sulfur batteries.     

非硅基介孔材料和介孔复合体的合成与特性

非硅基介孔材料和介孔复合体的合成与特性;介孔固体;介孔复合体;二氧化钛薄膜;液晶模板机理     

A Review of Recent Developments of Mesoporous Materials

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 (CO₂), 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.     

Mesoporous Silica Layer: Preparation and Opportunity

Periodic mesoporous silicas, which were prepared from silica‐surfactant mesostructured materials, have been investigated for a wide range of application due to their very large surface area, high porosity, pore size uniformity and variation, periodic pore arrangement and possible pore surface modification, after the pioneering papers on the formation of mesoporous silicas (MCM‐41 and FSM‐16). Morphosyntheses from such macroscopic morphologies as bulk monolith and film to nanoscopic ones, nanoparticles and their stable suspension, make mesoporous materials more attractive for applications and detailed characterization. Mesoporous silicas have been studied initially for such applications as adsorbent and catalyst, and more recently, optical, electronic, and bio‐related applications have been investigated. This review summarizes the studies on mesoporous silica film to highlight the present status and future of the preparation, characterization and application of the mesoporous silica film.     

有序介孔硅胶及其复合材料作固定相在液相色谱中的应用

系统地介绍了有序介孔硅胶及其复合材料的研究进展。重点评述了颗粒状无机介孔硅胶材料、颗粒状有机-无机复合介孔硅胶材料、手性介孔硅胶材料和整块介孔硅胶材料在用作液相色谱固定相方面的最新进展。对硅基有序介孔材料制备方面存在的问题进行了分析,并就该领域今后的发展趋势做了展望。     

Materials with Nanoscale Porosity: Energy and Environmental Applications

In this personal account, several key inventions on designing novel microporous and mesoporous materials, and their applications in energy and environmental research are reviewed. Although, crystalline materials with sub‐nanometer pore size regime like zeolites, AlPOs, MOFs, ZIFs etc. are known over the years, silicious and non‐silicious mesoporous materials have revolutionized the research on the materials with nanoscale porosity in last two and half decades. A wide range of inorganic, organic‐inorganic hybrid as well as purely organic mesoporous materials with either periodic or disordered mesopores are known. Apart from conventional hydrothermal syntheses involving soft templating route, hard templating, evaporation induced self‐assembly (EISA), electrochemical or solvothermal (using hydrophilic solvents) synthetic routes are often employed in designing a large spectrum of mesoporous materials. Ease of synthesis using available cheap raw chemicals and versatility in the framework compositions together with the unique surface properties like exceptionally high surface area, pore volume and tunability in pore dimensions have made these materials very exciting to a wide range of researchers working on materials chemistry. Nanoscale porosity in the semiconductor nanomaterials is highly beneficial for the photocatalytic, optoelectronic and related light‐harvesting applications. Their high chemical stability has been explored intensively in designing novel heterogeneous catalysts for the synthesis of biofuels from biomass or CO₂ fixation to reactive organic molecules for the synthesis of fine chemicals and fuels, which has a large impact on energy and environmental research for the years to come. Diversity in mesoporous frameworks and their potential applications related to light harvesting, generation of renewable energy and synthesis of value added fine chemicals and fuels through environment friendly routes are mostly focused in this review.     

Deposition of Layer－by－layer Inorganic－organic Nano－hybrid Ultrathin Films onto SBA－15

Deposition of inorganic-organic nano-hybrid ultrathin films onto mesoporous silicate materials has been proven possible by using layer-by-layer assembly method. In combination with sol-gel method, titania, subsequently dye molecules (or polymer) were successfully fabricated onto the inner wall of SBA-15. Their structures were preliminarily characterized by FTIR and solid-state UV-Vis spectroscopy, thermal analysis, and BET surface area measurements,respectively.     

由沸石纳米粒子自组装制备具有高催化活性中心和水热稳定的新型介孔分子筛材料

 人们合成了一系列介孔分子筛材料，并发现它们在催化、吸附与分离以及化学组装制备先进材料和分子器件等方面具有很大的潜在应用价值．但是，介孔分子筛材料相对于微孔沸石分子筛存在着两个致命弱点：较低的水热稳定性和较不活泼的催化活性中心．这两个弱点大大地影响了介孔分子筛在催化反应中的广泛应用．本文系统地综述了最近几年利用沸石纳米粒子自组装制备具有高催化活性中心和水热稳定的介孔分子筛材料的研究进展．这包括利用硅铝沸石纳米粒子自组装制备具有强酸性和水热稳定的新型介孔硅铝分子筛材料，利用钛硅沸石纳米粒子自组装制备具有高催化氧化活性中心和水热稳定的新型钛硅介孔分子筛材料，以及利用含有不同杂原子的沸石纳米粒子自组装制备一系列水热稳定的新型介孔分子筛催化材料．     

Ordered mesoporous metal oxides: synthesis and applications

Great progress has been made in the preparation and application of ordered mesoporous metal oxides during the past decade. However, the applications of these novel and interesting materials have not been reviewed comprehensively in the literature. In the current review we first describe different methods for the preparation of ordered mesoporous metal oxides; we then review their applications in energy conversion and storage, catalysis, sensing, adsorption and separation. The correlations between the textural properties of ordered mesoporous metal oxides and their specific performance are highlighted in different examples, including the rate of Li intercalation, sensing, and the magnetic properties. These results demonstrate that the mesoporosity has a direct impact on the properties and potential applications of such materials. Although the scope of the current review is limited to ordered mesoporous metal oxides, we believe that the information may be useful for those working in a number of fields.     

Synthesis of Mesoporous Molecular Sieves via a Novel Templating Scheme

Since Mobil researchers reported the discovery of a new family of silica-based mesoporous molecular sieves (M41S) materials in 1992^[1,2], there has been a growing interest in using these materials as heterogeneous catalysts, catalyst supports, and nanocomposite host materials for novel applications. All these applications have stimulated many researchers to synthesize mesoporous materials via different templating schemes or synthesis pathways. So far, ionic and neutral surfactant including neutral alkylamine^[3], polyethlene oxide^[4], genimi^[5], and amphiphilic triblock copolymer^[6] have been the most commonly used as templates for the directing the formation of mesoporous.