Development Of Mesoporous Materials Research Articles

Direct synthesis of ordered mesoporous materials from thermoplastic elastomers

The ability to manufacture ordered mesoporous materials using low-cost precursors and scalable processes is essential for unlocking their enormous potential to enable advancement in nanotechnology. While templating-based methods play a central role in the development of mesoporous materials, several limitations exist in conventional system design, including cost, volatile solvent consumption, and attainable pore sizes from commercial templating agents. This work pioneers a new manufacturing platform for producing ordered mesoporous materials through direct pyrolysis of crosslinked thermoplastic elastomer-based block copolymers. Specifically, olefinic majority phases are selectively crosslinked through sulfonation reactions and subsequently converted to carbon, while the minority block can be decomposed to form ordered mesopores. We demonstrate that this process can be extended to different polymer precursors for synthesizing mesoporous polymer, carbon, and silica. Furthermore, the obtained carbons possess large mesopores, sulfur-doped carbon framework, with tailorable pore textures upon varying the precursor identities.

Engineering ZnO nanocrystals anchored on mesoporous TiO2 for simultaneous detection of vitamins

Vitamins are essential for proper growth and development of the body. It is critical for the proper functioning of vital biological processes such as digestion, immunity, and metabolism, but their presence as deficiencies have been linked to number of different disorders. However, our bodies are unable to produce the essential vitamins, therefore we must obtain through intake of food. Electrochemical sensors provide a promising way for detection of vitamins because of its low cost and minimal signal-to-noise ratio could deliver high electrocatalytic performance towards target species. It has been reported that development of mesoporous materials as electrode materials can enhance the signal response with wide peak separation for detection of multivitamins. Generally, the addition of trace amount of metal oxide as dopant introduced on the surface of the host matrix can alter the physicochemical properties. Herein, the present work aims to develop mesoporous structure of TiO2 with doping of ZnO nanocrystals on its surface as efficient material for simultaneous determination of vitamin B (Riboflavin, B2 and pyridoxine, B6) and vitamin C (ascorbic acid). The presence of mesoporous structure could enhance the rapid diffusion of vitamin and the ZnO nanocrystals loaded on the cavities enables the fast electron transfer, as a result a large enhancement in the electrochemical signal response with wide separation of peak potentials for each vitamin are attained. A significant wide linear range for riboflavin (2–74 µM), ascorbic acid (7–154 µM) and pyridoxine (2–74 µM), respectively. The limit of detection (LOD) for determination of Vitamin B2, C and B6 was calculated to be 0.8 µM, 2.5 µM and 0.75 µM respectively. Overall, the high selectivity with significant enhancement in the current response by the binary metal oxide doped mesoporous structure can provide a new pathway for the design of low-cost electrode materials for various electrochemical and biomedical applications.

Recent advances in the synthesis of mesoporous materials and their application to lithium-ion batteries and hybrid supercapacitors

The ever-growing demand for high performance energy storage systems has fueled the development of advanced electrode materials with light weight, high energy/power densities, and stable cycle life. Mesoporous materials play an important role in achieving these goals because of their unique features such as high surface area, tunable pore size, pore volume, and pore structures, as well as adjustable particle size and morphology. In this review, we summarize the recent progress in the synthesis of mesoporous materials and their applications in lithium-ion batteries (LIBs) and lithium-ion hybrid supercapacitors (Li-HSCs) over the past ten years. The block copolymer guided soft-template route is highlighted as a simple and versatile tool for designing mesoporous materials with controlled nano-and macrostructures without complicated synthetic procedures. The structural/morphological benefits of designed mesoporous materials translate into highly improved electrochemical performance in LIBs and Li-HSCs. Finally, future challenges and perspectives on the development of mesoporous materials in energy storage devices are provided, which will be useful both in academia and in industry.

Development of mesoporous materials from biomass ash with future applications as adsorbent materials

Abstract This paper proposes the synthesis and functionalization of a low-cost mesoporous material from biomass ashes with the aim of obtaining a new adsorbent material, thereby recycling and transforming an environmental liability into a material with added value. Biomass ashes are an environmental liability, composed mainly of aluminosilicates, which have been modified with the help of a surfactant (Pluronic P-123) to model and modify its porous structure. The functionalization of the synthesized material was carried out with N, N-dimethylacetamide (DMAC) and glycine (GLY) in order to improve the adsorption capacity of the synthesized material. The materials obtained in this article were characterized by adsorption-desorption isotherms of N2 at 77 K, X-ray fluorescence (XFR), elemental analysis (EA), X-Ray diffraction (XRD), Fourier-transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoemission spectroscopy (XPS). The adsorption capacity of the synthesized matrices has been tested in batch and electrochemical systems. The surface areas obtained by the BET method were 18.49 m2 g−1 for pure ashes (CBT) and 22.84 m2 g−1 for modified ashes, and the adsorption capacities of Fe3+ ions were of about 80.49% for bare SC1, 83.27% for SC1-GLY and 95.41% for SC1-DMAC.

Some considerations regarding the mesopore structure and order in MSU-3 and MSU-F (organo)silicas

Development of mesoporous materials and specifically mesoporous silica was an advancement of that of microporous materials such as zeolites. Major advantages associated with mesopore nanostructures have largely depended on bigger pore size, high pore order and rather high flexibility in modification of the pore system. For this reason, large-pore and highly ordered mesoporous silica (e.g. SBA-15) were introduced taking advantage of co-polymer surfactants as structure directing agents, while pore size expansion was still extended toward making mesoporous silica foams. At the same time neutral cooperative self-assembly of silica precursors and non-ionic surfactants resulted in facile preparation of MSU-X family of mesoporous silica obtained in milder synthesis conditions. This research tries to bring new insights into the versatility of MSU-X preparations that would show highly ordered or engineered mesopore network. The mesostructural properties of MSU-3 and MSU-F materials subjected to hydrothermal processing and different functionalization were studied in detail with gas adsorption, TEM and XRD analyses. Use of different silica precursors and functionalizations brought differences in the mesopore structure. It was possible, in these syntheses, to obtain highly hexagonal mesopore order in the hybrid MSU-3 in a co-condensation synthesis with MPTMS in presence of inorganic silica precursor. On the other hand, during the course of silica foam (MSU-F) preparations, due to the effect of post-synthesis hydrothermal processing, considerable modification of the large mesopores brought the opportunity to achieve fully bimodal (both channel-like and mesocellular) pore morphologies in the material framework.

Synthesis of a New Class of Porous Carbon Materials from Polyacrylonitrile and Their Battery Applications

The development of mesoporous materials with well-defined pore size has been an ever-growing field over the last decade, finding versatile applications in academia and industry. Monoliths are functional macroporous materials with three-dimensional continuous interconnected pore structure in a single piece. They have received considerable attention due to their applications in chromatography, ion-exchange and catalysis which is attributed to their large permeability, fast mass transfer performance, high stability and ease of chemical modification. Polyacrylonitrile (PAN) is widely used as fibers in various industries. PAN fibers are also good precursor of high-quality carbon fibers. This study mainly deals with fabrication of mesoporous PAN monolith by thermally induced phase separation (TIPS) and its conversion to activated carbon monolith (ACM), which has large potential for battery applications. Furthermore, porous PAN particles were prepared by the dispersion polymerization, which were converted to porous carbon particles showing relatively large electrical capacity.PAN is insoluble in water but soluble in mixture of water and DMSO. Monoliths of PAN with meso-scale pores were fabricated by dissolution of the polymer in the mixture of solvents by heating, followed by cooling: A newly developed facile and easy technique viz. TIPS.1) The shape of the monoliths could be modified by altering the shape of the vessel. The general procedure for the synthesis of mesoporous polymer monolith is illustrated in Figure 1. SEM images of the PAN monolith show that a continuous interconnected network of polyacrylonitrile was successfully prepared consisting of macropores. The skeleton size for the microstructures was ca. 0.6-1.0 µm whereas the pore sizes lie between 0.8-2.1 µm. A magnified view of the surface morphology of the PAN monolith shows that the skeleton of the macropores were uniformly porous all over with size of the pores lying in the mesoporous range. The BET surface area of the monoliths varied from 160-225 m2/g which depended on the preparation conditions e.g. solvent ratio, heating temperature and duration of homogenization. A highly porous ACM from the mesoporous PAN monolith via thermal treatment in two-steps: activation in air leading to cyclization and subsequent aromatization of the polyacrylonitrile moieties followed by carbonization in Ar or Ar/CO2 mixture.2) ACM thus produced had a nitrogen content of ca. 4.4 wt. % with high BET surface area (ca. 1400 m2/g) and narrow micropore size distribution. The average pore diameter of ACM was about 7.4 Å, which reveal the microporous structure. Cyclic voltammetry showed relatively large electrostatic capacitance of ACM.Porous PAN materials were also obtained by dispersion polymerization of AN using poly(N-vinylpyrrolidone) as stabilizer in a mixture of DMF and methanol. The obtained monodisperse particles in the diameter of ca. 1 mm were converted to porous activated carbon particles with high BET surface area (ca.2600 m2/g), which also exhibited good capacitance properties even at high scan speed.1) K. Okada, M. Nandi, J. Maruyama, T. Oka, T. Tsujimoto, K. Kondoh, H. Uyama, Chem. Commun., 47, 7422 (2011).2) M. Nandi, K. Okada, A. Dutta, A. Bhaumik, J. Maruyama, D. Derks, H. Uyama, Chem. Commun., 48, 10283 (2012).

Organically Functionalized Mesoporous Silica by Co‐structure‐Directing Route

AbstractThis article provides a brief overview of functional mesoporous silica materials synthesized by the co‐structure‐directing route, which is distinct from conventional synthesis strategies. In these systems, organosilane serves as the co‐structure‐directing agent (CSDA), which provides critical interactions between the template and organic part of the organosilane to form mesostructures, thus retaining the organic groups on the pore surface after removal of the template by extraction. i) The formation of anionic‐surfactant‐templated mesoporous silicas (AMSs) has been achieved by the co‐structure‐directing route, which leads to a variety of mesostructures, porous properties and morphologies. ii) Other co‐structure‐directing systems for synthesizing mesoporous silicas have also been achieved, including systems using cationic surfactants and non‐surfactants, and systems using DNA for constructing nanofibers and DNA–silica liquid crystalline complexes. iii) Evidence for the regular arrangement of functional groups on the pore surface resulted from the co‐structure‐directing effect has been discussed. Also included is a brief description of the application, future requirements, and trends in the development of mesoporous materials by the co‐structure‐directing route.

Structure of Mesoporous Aerogels

Several emerging technologies depend on the development of porous materials with pore dimensions in the nanometer range (1 nm = 10 Å). Based on the canonical classification scheme, such materials are defined as “mesoporous materials.” Specialty uses, such as separation applications, require porosities engineered to meet stringent pore-size requirements, particularly for separating high-boiling-temperature or-ganics. In addition, commodity products, such as high-performance thermal insulation, await credible manufacturing methods to produce fine-scale pores. Finally, information discovered during the development of mesoporous materials could be helpful in finding new strategies to generate void-free ceramic materials by reverse engineering.Although several methods exist to generate nanometer porosity, our ability to tailor porosity for specific applications is still primitive. Because we lack adequate structural data and models for pore formation, the relationship between synthetic protocol and pore structure remains enigmatic.