Functional Mesoporous Materials Research Articles

Controllable deposition of TiO2 nanopillars at room temperature for high performance perovskite solar cells with suppressed hysteresis

A room temperature stratagy was proposed and realized for the fabrication of TiO2 scaffold for perovskite solar cells (PSCs). By sueccetively sputtering TiO2, thermal evaporating PTFE template and sputtering TiO2 again, bilayer TiO2 electron extraction layer was prepared with controllable porosity. Owning to the high sputtering power, the electron transport layer consisting of compact layer and TiO2 nanopillars was fully crystallized and no post thermal treatment was needed for the removal of PTFE template. The hysteresis of PSC was modulated and the porosity dependence of hysteresis was analyzed. PSC with a PCE of 15.08% and neglectable hysteresis was fabricated when the porosity of mesoporous scaffold was 45.77%. Our methodology offered a low cost room temperature scheme for the fabrication of mesostructured PSC. This approach makes large scale flexible PCS devices possible. What is more, this technique is versatile for the preparation of functional mesoporous materials with different pore structure and porosity requirements.

Structural aspects of graphitic carbon modified SBA-15 mesoporous silica and biological interactions with red blood cells and plasma proteins

Functional mesoporous materials have been worldwide studied for different applications. Mesoporous silicas are highlighted due to the synthetic possibilities for the preparation of such materials with different particle sizes and morphologies, and controlled pores sizes and structures. Moreover, the silica superficial silanol groups are explored in several chemical modifications, leading to functional materials with tuned functionalities and properties.In this work, an organo-functionalization and pyrolysis synthetic procedure is used to obtain graphitic carbon modified mesoporous SBA-15 silica. The carbon content was tuned during the functionalization step, and the graphitic nanodomains were formed in the pores surface and particles outer surface. Textural and small angle X-ray diffraction analysis accessed the presence of the carbon nanostructures inside the SBA-15 mesopores. Advanced microanalysis using electron energy loss spectroscopy coupled to a transmission electron microscope had confirmed the carbon distribution along the silica pores, which gives higher hydrophobicity and changed the interaction of the mesoporous material with biological systems.Finally, the influence of the surface modification with graphitic carbon species over the interaction with human red blood cells (hemolysis) and human blood plasma (protein corona formation) was elucidated for the very first time for this kind of functional materials. It was observed that the graphitic carbon species considerably reduced the hemolytic effect of the silica particles, and was responsible for modulating the loading and composition of the hard corona plasma proteins. This work deepness the fundamental knowledge on the interaction between such nanomaterials and biological systems, one step further the use of these modified silicas in biomedical applications.

Fabrication of diverse pH-sensitive functional mesoporous silica for selective removal or depletion of highly abundant proteins from biological samples

In proteomic studies, poor detection of low abundant proteins is a major problem due to the presence of highly abundant proteins. Therefore, the specific removal or depletion of highly abundant proteins prior to analysis is necessary. In response to this problem, a series of pH-sensitive functional mesoporous silica materials composed of 2–(diethylamino)ethyl methacrylate and methacrylic acid units were designed and synthesized via atom transfer radical polymerization. These functional mesoporous silica materials were characterized and their ability for adsorption and separation of proteins was evaluated. Possessing a pH-sensitive feature, the synthesized functional materials showed selective adsorption of some proteins in aqueous or buffer solutions at certain pH values. The specific removal of a particular protein from a mixed protein solution was subsequently studied. The analytical results confirmed that all the target proteins (bovine serum albumin, ovalbumin, and lysozyme) can be removed by the proposed materials from a five–protein mixture in a single operation. Finally, the practical application of this approach was also evaluated by the selective removal of certain proteins from real biological samples. The results revealed that the maximum removal efficiencies of ovalbumin and lysozyme from egg white sample were obtained as 99% and 92%, respectively, while the maximum removal efficiency of human serum albumin from human serum sample was about 80% by the proposed method. It suggested that this treatment process reduced the complexity of real biological samples and facilitated the identification of hidden proteins in chromatograms.

A Highly Ordered N-Rich Functionalized Mesoporous Material for CO<SUB>2</SUB> Storage Application

A Highly Ordered N-Rich Functionalized Mesoporous Material for CO<SUB>2</SUB> Storage Application

Single-Nanometer-Sized Low-Valence Metal Hydroxide Crystals: Synthesis via Epoxide-Mediated Alkalinization and Assembly toward Functional Mesoporous Materials

Single-Nanometer-Sized Low-Valence Metal Hydroxide Crystals: Synthesis via Epoxide-Mediated Alkalinization and Assembly toward Functional Mesoporous Materials

A New Insight into Growth Mechanism and Kinetics of Mesoporous Silica Nanoparticles by in Situ Small Angle X-ray Scattering.

The growth mechanism and kinetics of mesoporous silica nanoparticles (MSNs) were investigated for the first time by using a synchrotron time-resolved small-angle X-ray scattering (SAXS) analysis. The synchrotron SAXS offers unsurpassed time resolution and the ability to detect structural changes of nanometer sized objects, which are beneficial for the understanding of the growth mechanism of small MSNs (∼20 nm). The Porod invariant was used to quantify the conversion of tetraethyl orthosilicate (TEOS) in silica during MSN formation, and the growth kinetics were investigated at different solution pH and temperature through calculating the scattering invariant as a function of reaction time. The growth of MSNs was found to be accelerated at high temperature and high pH, resulting in a higher rate of silica formation. Modeling SAXS data of micelles, where a well-defined electrostatic interaction is assumed, determines the size and shape of hexadecyltrimethylammonium bromide (CTAB) micelles before and after the addition of TEOS. The results suggested that the micelle size increases and the micelle shape changes from ellipsoid to spherical, which might be attributed to the solubilization of TEOS in the hydrophobic core of CTAB micelles. A new "swelling-shrinking" mechanism is proposed. The mechanism provides new insights into understanding MSN growth for the formation of functional mesoporous materials exhibiting controlled morphologies. The SAXS analyses were correlated to the structure of CTAB micelles and chemical reaction of TEOS. This study has provided critical information to an understanding of the growth kinetics and mechanism of MSNs.

Facile Synthesis of Prussian Blue Derivate‐Modified Mesoporous Material via Photoinitiated Thiol–Ene Click Reaction for Cesium Adsorption

A novel strategy to synthesize a functional mesoporous material for efficient removal of cesium is reported. Specifically, Prussian blue derivate-modified SBA-15 (SBA-15@FC) was prepared by photoinitiated thiol-ene reaction between thiol-modified SBA-15 and pentacyano(4-vinyl pyridine)ferrate complex. The effects of weight percentage of the Prussian blue derivate, pH, adsorbent dose, co-existing ions, and initial concentration were evaluated on the adsorption of cesium ions. The adsorption kinetically follows a pseudo-second-order model and reaches equilibrium within 2 h with a high adsorption capacity of about 13.90 mg Cs g(-1) , which indicates that SBA-15@FC is a promising adsorbent to effectively remove cesium from aqueous solutions.

Phospholipid-stabilized mesoporous carbon nanospheres as versatile carriers for systemic delivery of amphiphobic SNX-2112 (a Hsp90 inhibitor) with enhanced antitumor effect

Systemic delivery of amphiphobic drugs (insoluble in both water and oil) represents a formidable challenge in drug delivery. This work aimed to engineer a functional mesoporous carbon material to efficiently load SNX-2112, an amphiphobic anticancer agent, and to evaluate its performance in tumor-targeting delivery. Hydrothermal reaction combined with high-temperature activation was used to fabricate glucose-based mesoporous carbon nanospheres (MCNs). SNX-2112-loaded MCNs stabilized by phospholipid (SN-PMCNs) were prepared by the absorption/solvent diffusion/high-pressure homogenization method. The obtained SN-PMCNs were 180nm around in particle size, showing a high drug load (42.7%) and acceptable physical stability. SN-PMCNs demonstrated an enhanced in vitro antitumor effect and increased uptake into cancer cells in comparison with the formulation of SNX-2112 solution (SN-Sol). The in vivo antitumor effect and biodistribution in 4T1 xenograft tumor mice, a breast cancer model, were also significantly improved through SN-PMCNs. It was shown that specific clathrin-dependent and nonspecific caveolae-dependent endocytosis were involved in the cellular trafficking of SN-PMCNs. Glucose transporter-mediated transport, prolonged body residence time and improved biodistribution via EPR effect were the main mechanisms of enhanced antitumor effect. SN-PMCNs have presented excellent tumor targeting properties and should be a promising carrier to address the systemic delivery of SNX-2112.

Simple way to obtain pH-sensitive drug release from functional mesoporous silica materials.

A novel pH-sensitive drug release system has been synthesised by functional mesoporous silica materials. SBA-15, calcium modified SBA-15 (Ca-SBA-15) and phosphate modified SBA-15 (PO4-SBA-15) were synthesised using solvent evaporation method. It is a simple and feasible way to prepare the doping mesoporous silica materials. They show the large surface are, high pore volume and uniform pore size. Metformin hydrochloride was used as the model drug, and the control release behaviour was investigated. The functional mesoporous silica materials show the pH sensitive drug release behaviour because of the adjustable interaction between the drug molecule and the host.

Biphase Stratification Approach to Three-Dimensional Dendritic Biodegradable Mesoporous Silica Nanospheres

A kind of novel uniform monodispersed three-dimensional dendritic mesoporous silica nanospheres (3D-dendritic MSNSs) has been successfully synthesized for the first time. The 3D-dendritic MSNSs can have hierarchical mesostructure with multigenerational, tunable center-radial, and dendritic mesopore channels. The synthesis was carried out in the heterogeneous oil-water biphase stratification reaction system, which allowed the self-assembly of reactants taking place in the oil-water interface for one-pot continuous interfacial growth. The average pore size of each generation for the 3D-dendritic MSNSs can be adjusted from 2.8 to 13 nm independently, which can be controlled by the varied hydrophobic solvents and concentration of silica source in the upper oil phase. The thickness of each generation can be tuned from ∼ 5 to 180 nm as desired, which can be controlled by the reaction time and amount of silica source. The biphase stratification approach can also be used to prepare other core-shell and functional mesoporous materials such as Au nanoparticle@3D-dendritic MSNS and Ag nanocube@3D-dendritic MSNS composites. The 3D-dendritic MSNSs show their unique advantage for protein loading and releasing due to their tunable large pore sizes and smart hierarchical mesostructures. The maximum loading capacity of bovine β-lactoglobulin with 3D-dendritic MSNSs can reach as high as 62.1 wt % due to their large pore volume, and the simulated protein releasing process can be tuned from 24 to 96 h by flexible mesostructures. More importantly, the releasing rates are partly dependent on the hierarchical biodegradation, because the 3D-dendritic MSNSs with larger pore sizes have faster simulated biodegradation rates in simulated body fluid. The most rapid simulated biodegradation can be finished entirely in 24 h, which has been greatly shortened than two weeks for the mesoporous silica reported previously. As the inorganic mesoporous materials, 3D-dendritic MSNSs show excellent biocompatibility, and it would have a hopeful prospect in the clinical applications.

Synthesis of Amine-Functionalized MCM-41 and MCM-48 for Removal of Heavy Metal Ions from Aqueous Solutions

In this research amino functional mesoporous MCM-41 and MCM-48 materials were prepared in an attempt to develop efficient adsorbents for removal of heavy metals from aqueous solutions. The adsorbents were characterized by XRD, FTIR, and TG-DTG techniques. The synthesized adsorbents were used for the removal of Cu(II), Co(II), Cd(II), and Pb(II) from aqueous solutions for the first time, and the influence of some effective parameters including concentration, initial pH, contact time, and temperature on the sorption process was studied and optimized. Significant adsorption capacities were obtained at low concentrations. The kinetic studies showed that the adsorption process was fast and more than 90% of equilibrium capacity was achieved within 60 min. Experimental kinetic data was well fitted with the pseudo-second-order kinetic model. Thermodynamic parameters computed from the experimental data showed that the adsorption was endothermic and spontaneous.

Template-free synthesis of uniform magnetic mesoporous TiO2 nanospindles for highly selective enrichment of phosphopeptides

A novel, simple and template-free strategy was developed for the synthesis of uniform magnetic mesoporous TiO2 nanospindles. Unlike previous synthetic approaches which mainly involve the strict control of sol–gel processes, templates, or capping agents, our strategy is based on an additional post-hydrolysis route, giving rise to mesoporous TiO2 with a high surface area (366 m2 g−1). After crystallization, the mesoporous TiO2 nanospindles obtained a high surface area (∼117 m2 g−1) and a large pore size (∼5.4 nm), and exhibited a high magnetic susceptibility (∼18.0 emu g−1), as well as showed a remarkable performance for highly selective and rapid enrichment of phosphopeptides with an unprecedented enrichment capacity of ∼300 mg g−1. These understandings open up a new way for the preparation of functional mesoporous TiO2-based materials with high surface areas in a template-free manner, which is of significant importance for applications from both environmental and industrial points of view.

Self-Assembly Mechanism of Folate-Templated Mesoporous Silica

A method to form ordered mesoporous silica based on the use of folate supramolecular templates has been developed. Evidence based on in situ small-angle X-ray scattering (SAXS), electron microscopy, infrared spectroscopy, and in situ conductivity measurements are used to investigate the organic-inorganic interactions and synthesis mechanism. The behavior of folate molecules in solution differs distinctively from that of surfactants commonly used for the preparation of ordered mesoporous silica phases, notably with the absence of a critical micellar concentration. In situ SAXS studies reveal fluctuations in X-ray scattering intensities consistent with the condensation of the silica precursor surrounding the folate template and the growth of the silica mesostructure in the initial stages. High-angle X-ray diffraction shows that the folate template is well-ordered within the pores even after a few minutes of synthesis. Direct structural data for the self-assembly of folates into chiral tetramers within the pores of mesoporous silica provide evidence for the in register stacking of folate tetramers, resulting in a chiral surface of rotated tetramers, with a rotation angle of 30°. Additionally, the self-assembled folates within pores were capable of adsorbing a considerable amount of CO2 gas through the cavity space of the tetramers. The study demonstrates the validity of using a naturally occurring template to produce relevant and functional mesoporous materials.

Synthesis and properties of novel functional mesoporous materials

Structurally well-defined mesoporous materials with large surface area and homogeneous pore diameters have been intensively investigated in recent years, furthermore, organofunctionalized mesoporous materials have attracted much attention for their potential application in many fields, such as separation, adsorption and drug delivery. In this paper, fluorescent mesoporous materials were successfully synthesized through “Grafting” method by mesoporous materials and silicon nanocrystals. A comprehensive multi-analytical characterization of the structural and optical properties of the fluorescent materials was carried by fourier transform infrared spectroscopy, powder X-ray diffraction, nitrogen adsorption–desorption measurements, scanning electron microscopy and transmission electron microscope. The behavior of loading and release to ibuprofen has been tested. The fluorescent materials which integrated with two functional components displayed potential in optoelectronic and biomedical applications.

Cover Picture: Sol–Gel Coordination Chemistry: Building Catalysts from the Bottom‐Up / Editorial: From Mesoporous Supports to Mesoporous Catalysts: Introducing Functionality to Mesoporous Materials (ChemCatChem 4/2013)

Building better catalysts from the bottom-up The cover picture shows how mesoporous catalysts can now be fabricated using building blocks containing a wide variety of chemical functionalities. In their Review on p. 844 ff., E. Serrano et al. describe the use of silicon alkoxide-terminated nanoparticles and metal complexes as building blocks in the preparation of functional mesoporous materials containing these moieties in their pore walls and their catalytic performance. In their Editorial of this Special Issue, R. Luque and J. Garcia Martinez expand on this idea and the potential of bottom-up strategies in the synthesis of better catalysts (p. 827 ff.).

Synthesis of teicoplanin-modified hybrid magnetic mesoporous silica nanoparticles and their application in chiral separation of racemic compounds

Teicoplanin-conjugated mesoporous silica magnetic nanoparticles (TE-MSMNPs) were fabricated as novel chiral magnetic nano-selectors. Successful preparation of the functional magnetic mesoporous materials was achieved by grafting teicoplanin on N-(2-aminoethyl)-3-aminopropyltrimethoxysilane-modified mesoporous silica Fe3O4 magnetic nanoparticles (AEAPTMS-MSMNPs), and this was confirmed by various characterization techniques. The synthesized magnetic nanoparticles were regularly spherical and uniformly mesoporous with an average diameter of around 600nm and a mean pore size of about 3.9nm, respectively. These versatile magnetic nanoparticles were effective in a direct chiral separation of five racemic compounds in phosphate buffer. Much stronger interactions were observed with the (+)-enantiomers than with the (−)-enantiomers. After washing with water and ethanol by sonication, TE-MSMNPs could be reused at least three times with little efficiency loss. The functional magnetic mesoporous nanoparticles were easily separated from the racemic solutions using an external magnetic field. These magnetic nano-materials are suitable for enantiomer separations.

Green graft process for preparation of functional mesoporous silica materials

This study presents a green post-grafting method to prepare functional mesoporous silica materials. In the functionalisation stage, potassium iodide was applied as catalyst, and ecofriendly ethanol was used as solvent. The optimal molecular ratio of the reagent was n (potassium iodide)/n (3-chloropropyltriethoxysilane)/n (2-mercaptobenzothiazole) = 1·5∶1∶1·5. The reaction could be completed after reflux for 12 h at 90°C. The resulting materials were characterised by scanning electron microscopy, X-ray diffraction, nitrogen adsorption–desorption, Fourier transform infrared spectroscopy and elemental analysis. The results indicate that the large pore (the maximal size is ∼8·62 nm) functional mesoporous silica could be prepared by our improved graft method, which has a high efficiency of 50·63%. The functional mesoporous silica was applied to adsorb trace amount of heavy metal ions [Hg(II), Pb(II) and Cd(II)]. The materials exhibit large adsorption capacity and excellent regeneration ability.

Designing Functionalized Mesoporous Materials for Enzyme Immobilization: Locating Enzymes by Using Advanced TEM Techniques

AbstractOne of the widely accepted uses of ordered mesoporous materials is as supports of enzymes for biotechnological applications. Enzymes have been trapped, anchored, or encapsulated in organized porous networks of the mesoporous range (2–50 nm). The reactivity of the surface of mesoporous materials has enabled the synthesis of various supports by using different forces for the immobilization process. To design catalysts for specific applications, we have developed functionalized mesoporous materials with tunable hydrophobicity for the immobilization of lipase. More recently, we moved to the immobilization of laccase with amino‐functionalized ordered mesoporous materials. In this case, it is required to use pore expanders along with optimized functionalization techniques. Advanced TEM techniques have been applied to locate not only the functional groups but also the macromolecules inside the silica matrix.

様々なメソ（ナノ）多孔体の合成と応用

様々なメソ（ナノ）多孔体の合成と応用

Functional mesoporous materials for energy applications: solar cells, fuel cells, and batteries

This feature article presents recent progress made in the synthesis of functional ordered mesoporous materials and their application as high performance electrodes in dye-sensitized solar cells (DSCs) and quantum dot-sensitized solar cells (QDSCs), fuel cells, and Li-ion batteries. Ordered mesoporous materials have been mainly synthesized using two representative synthetic methods: the soft template and hard template methods. To overcome the limitations of these two methods, a new method called CASH was suggested. The CASH method combines the advantages of the soft and hard template methods by employing a diblock copolymer, PI-b-PEO, which contains a hydrophilic block and an sp(2)-hybridized-carbon-containing hydrophobic block as a structure-directing agent. After discussing general techniques used in the synthesis of mesoporous materials, this article presents recent applications of mesoporous materials as electrodes in DSCs and QDSCs, fuel cells, and Li-ion batteries. The role of material properties and mesostructures in device performance is discussed in each case. The developed soft and hard template methods, along with the CASH method, allow control of the pore size, wall composition, and pore structure, providing insight into material design and optimization for better electrode performances in these types of energy conversion devices. This paper concludes with an outlook on future research directions to enable breakthroughs and overcome current limitations in this field.