Monolithic Silica Research Articles

Demonstration of high separation efficiency for polystyrene-modified sub-1 µm particles originating from silica monolith under isocratic elution mode in liquid chromatography

Renovated protocols for the synthesis and modification of sub-1 µm porous particles originating from silica monolith coupled with sophisticated packing procedures have made it possible to get excellent separation efficiency and the possibility for rapid analysis when dealing with five benzene derivatives in high-performance liquid chromatography. The catalyst-assisted binding of 4-chloromethylphenyl-isocynate and consequent reversible addition-fragmentation chain transfer (RAFT) polymerization enabled the attachment of uniform polymer film onto the silica particles. The column (1.0 mm ID × 300 mm length) packed with such particles resulted in supreme separation efficiency (256,200 plates/m) which is comparable to the separation efficiency of column packed with core shell particles. The optimum separation was obtained in 65/35 (v/v %) acetonitrile/water with 0.1% trifluoroacetic acid at a flow rate of 28 µL/min. Particle size reduction with increased pore size along with sophisticated packing protocol, partial monolithic architecture of the packed bed, and uniformly distributed polymer film are the beneficial features responsible for the improved chromatographic performance of the final stationary phase.

Indoor CO2 Control through Mesoporous Amine-Functionalized Silica Monoliths

Amine-functionalized adsorbents have attracted much attention in removing indoor CO to reduce the risk of human health. In the current work, polyethyleneimine (PEI)-modified silica monolith (PEI-silica) was synthesized through a sol-gel method using PEI with molecular weights of 750,000, 25,000, and 10,000 as template agents. The N adsorption result revealed that the PEI-silica monolith possesses a mesoporous structure with 25-45 nm pore size assembled by silica particles (60-80 nm), which was decreased with the decrease in PEI molecular weight. The adsorption capacities of PEI-silica for reducing CO concentration below 0.1% from 0.5% were investigated. The results indicated that CO adsorption capacity of PEI-silica increased as molecular weight of PEI decreased. PEI-silica achieved CO adsorption capacities of 58.5 and 100.4 mg g under dry and humid conditions and showed cyclic stability during a 10 times adsorption-desorption process. Therefore, PEI-silica monolith provides a promising strategy for controlling indoor CO.

Critical Review—Photostable Fluorescent Cd-Free Quantum Dots Transparently Embedded in Monolithic Silica

Fluorescent Cd-free quantum dots (QDs) such as InP/ZnS and CuInS2/ZnS have attracted attention for use as color converters for blue light emitting diodes. To protect QDs from oxygen, which degrades them by photo-oxidation during excitation, we fabricated a transparent monolithic silica composite containing the QDs using an aqueous solution of tetramethylammonium silicate (TMAS) as a silica source. The TMAS solution readily dispersed the negatively charged QDs prepared by ligand exchange of 1-dodecanethiol for 3-mercatopropionic acid (MPA). A highly transparent monolithic TMAS-derived silica composite containing the MPA-capped QDs was obtained from the QD dispersion through a sol–gel process. Improved photostability of QDs was explained by the TMAS-derived silica acting as a gas barrier to protect the embedded QDs from photo-oxidation by oxygen in air.

Investigation of the interaction between serotonin-related compounds and phenylboronate moieties in monolithic silica disk-packed spin columns.

Solid-phase extraction technologies are widely used for sample pretreatment in bioanalysis. Monolithic silica disk-packed spin columns modified with phenylboronate moieties have been developed for the selective extraction of cis-diol compounds such as catecholamines. However, in our preliminary studies, serotonin was found to also be extracted in this treatment, along with catecholamines. In this study, the interaction between serotonin-related compounds (serotonin, tryptophan, 5-hydroxy-tryptophan and 5-hydroxyindoleacetic acid) and phenylboronate moieties was investigated. We found that only serotonin was extracted with phenylboronate-modified monolithic silica, whereas tryptophan, 5-hydroxy-tryptophan and 5-hydroxyindoleacetic acid were not. Hydrophobic interactions rather than ionic interactions were the primary factor for the adsorption of serotonin to phenylboronate. Finally, the selective pretreatment procedure for catecholamines was improved: thus, the method could be applied for the pretreatment of bio-samples.

Ambient pressure dried flexible silica aerogel for construction of monolithic shape-stabilized phase change materials

Flexible monolithic silica aerogel was prepared using an ambient pressure drying method without extra modifying and solvent-exchange process by controlling the crosslinking degree of the network and in-situ modification of methyl groups to the siloxane backbone. The introduction of the CH3-riched trimethylmethoxysilane (TMMS) molecules transforms silica clusters from originally rigid network structure with high crosslinking degree into flexible network structure with low crosslinking degree, not only improving the flexibility of the aerogel, but also endowing the hydrophobic property. The monolith feature, flexibility, hierarchical porous structure and hydrophobicity make the aerogel an ideal porous support for fabricating shape-stabilized phase change materials (PCMs). The obtained monolithic Paraffin (PA)/Aerogel composite shows high loading amount of PCMs, enhanced phase change enthalpy and good thermal stability. It is convenient to produce diverse shapes of monolithic composite PCMs to satisfy a range of specific requirements for energy storage applications.

Highly reusable visible light active hierarchical porous WO3/SiO2 monolith in centimeter length scale for enhanced photocatalytic degradation of toxic pollutants

To develop techniques like photocatalytic degradation of toxic-pollutants to reduce water pollution is essential as every human being has the right to have an access to safe water. Metal oxide monoliths have a huge significance regarding this due to their easy-to-separate nature. Porous WO3/SiO2 monoliths were synthesized by vacuum-impregnation of sodium tungstate in silica monoliths and calcination. The XRD spectra confirmed the successful formation of monolith and the morphological studies were done by FESEM exhibiting a connected porous network structure. The elemental-state and uniform elemental-distribution were analyzed by XPS and EDS. BET analysis showed that monoliths displayed multimodal porosity with pore-diameter of 0.70–14.71 nm and high surface area (82 m2/g). DRS revealed that the monolith had a narrow band gap (2.5 eV), which is suitable for visible light photocatalysis. The photocatalytic performance of monolith was estimated by degradation of model-pollutant methylene blue (MB) under visible-light illumination. High photocatalytic efficiency (91%) and rate constant (0.013 min−1) was observed at natural pH of the dye (pH 7.5). The effect of pH and catalyst concentration was explored which revealed that best degradation occurred at pH 3 (97.5%) and catalyst concentration 0.4 g/L (96%). The trapping experiments suggested that the holes were governing reactive-species in the reaction. The photocatalyst was reused for 5 consecutive cycles (80% degradation). The characterization-results of monolith after 2nd cycle of photodegradation explicated its stability. A colorless-pollutant (Imidacloprid) was also degraded to distinguish between direct and indirect photocatalysis. A comparative study was also done with reported catalysts in literature regarding MB degradation.

Tailor-made porous polymer and silica monolithic designs as probe anchoring templates for the solid-state naked eye sensing and preconcentration of hexavalent chromium

We present a facile approach towards the fabrication of solid state optical sensors for the naked-eye sensing of carcinogenic Cr6+ ions, using porous polymer and silica monoliths, as probe anchoring templates. The monoliths proffer superior structural properties of high surface area and capacious pore size for the uniform and voluminous probe anchoring. The surface morphology and structural features of the monoliths are analyzed using various surface and structural characterization techniques. The solid-state optical sensors are concocted by the transmogrification of monoliths through impregnation of an amphipathic chromoionophore i.e., 1,5-bis-(4-butylphenyl)carbazone (BBPC), as the ion-sensing probe. The sensors offer long-term stability and rapid response kinetics (< 10 min) with superior ion-selectivity for ultra-trace Cr6+ ions. The ascendancy of physicochemical parameters with reference to solution pH, probe concentration, response kinetics, medium temperature, sensor capacity, linear signal response, selectivity, and sensitivity has been optimized. The sensors exhibit a linear signal response for Cr6+ ions in the concentration range of 5–125 ppb and 3–150 ppb, for silica and polymer sensors, respectively. The solid-state sensor systems exhibit excellent data reliability and reproducibility (RSD ≤ 2.85%), with an LD of 1.87 and 0.41 ppb, and an LQ of 6.23 and 1.36 ppb, for silica and polymer sensors, respectively.

Linking the multiscale porous structure of hexacyanoferrate-loaded silica monoliths to their hydrodynamic and cesium sorption properties

Multiscale porous silica monoliths functionalized with potassium/copper hexacyanoferrate (HCF) have been evaluated for the column extraction of cesium from natural water. Compared with commercial silica gel particles, results show that the hierarchically porous architecture of the monoliths improves the bed efficiency in column extraction, and the selectivity, distribution coefficient and exchange kinetics in batch extraction. Cesium breakthrough experiments show that these preferable properties of the monolithic structure are maintained in column operation. This analysis of the batch and breakthrough experiments is supported by scanning and transmission electron microscopy data, residence time distributions, and reactive transport modeling assuming dispersive flow in the macroporous intraskeletal channels and diffusion inside the walls of the structure and the HCF aggregates.

Conditional Alox12b Knockout: Degradation of the Corneocyte Lipid Envelope in a Mouse Model of Autosomal Recessive Congenital Ichthyoses

Conditional Alox12b Knockout: Degradation of the Corneocyte Lipid Envelope in a Mouse Model of Autosomal Recessive Congenital Ichthyoses

Solid Nano-Composite Electrolytes (nano-SCE) with Ion Conductivity Promotion at an Interfacial Ice Layer on the Mesoporous Silica Matrix

The transition to solid-state Li-ion batteries requires solid electrolytes with Li-ion conductivity exceeding 1 mS/cm. Solid composite electrolytes or SCEs consisting of an ionic conductor and a dielectric matrix offers an elegant strategy to enhance the ionic conductivity of electrolytes by engineering the interface conduction. Composite electrolyte materials with inorganic oxide matrixes such as silica, alumina or titania with, for example, inorganic or polymer electrolytes have indeed shown enhancements in ion conductivity, however, the total ion conductivity was still well below 1mS/cm due to the low conductivity of the starting individual electrolytes used. Also composites of mesoporous oxide matrix filled with non-volatile ionic liquid electrolyte (ILE) fillers have been explored as solid electrolyte option. The advantage is that ILE can already have quite high ionic conductivity as individual electrolyte component. However, simple confinement of an electrolyte solution in nanometer size pores results in lower conductivity as its effective viscosity increases. The decrease in ion conductivity is expected the worse for mesoporous channels (~10nm in diameter) where the ionic liquid can even turn solid. To achieve higher ion conductivity, interface enhancement has to exceed the decrease in conductivity by confinement. Monolithic nanoporous silica with ILE confined in the porous structures, also named “ionogels” have shown ion conductivities approaching that of the ILE bulk conductivity, indeed, indicating the presence of interface enhancement in these materials. However, so far, the ionic conductivity of the confined ILE in the nanoporous oxide has never exceeded that of the ILE conductivity itself. These ionogels are fabricated by a sol-gel process e.g. by hydrolysis-condensation reaction with tetra-ethylorthosilicate (TEOS) precursor and typically formic acid where the ILE is added in the solution as the template for the silica to grow around. In this paper we demonstrate that the Li-ion conductivity of nano-composites consisting of a mesoporous silica monolith with an ionic liquid electrolyte as filler can be several times higher than that of the pure ionic liquid electrolyte itself when the silica surface is appropriately hydroxylated. Interfacial ice layers induce strong adsorption and ordering of the ionic liquid molecules through H-bonding rendering it immobile and solid-like as for the interfacial ice layer itself. The dipole over the adsorbate results in solvation of the Li+ ions for enhanced conduction. The existence of an interfacial mesophase layer is proven by Infrared and Raman spectroscopy. Higher Li-ion diffusion coefficients for the nanocomposite compared to the pure ionic liquid electrolyte reference is shown by Pulsed-Field-Gradient NMR. The principle of ion conduction enhancement is generic and could be applied to different ion systems. The concept also allows for further (nano)engineering towards specific properties of ion conduction, transport number, electrochemical window, safety and cost for future battery cell generations. The nano-SCE was fabricated in a similar way as the ionogels: a single-step sol-gel process with a TEOS precursor and with the ionic liquid electrolyte in the homogeneous precursor solution, except we did not use formic acid but water. We will focus on systematic study of our nano-SCE model system with (N-butyl- N-methyl pyrrolidinium bis(trifluoromethanesulfonyl) imide ([BMP]TFSI) and bis(trifluoromethanesulfonyl)imide lithium salt (LiTFSI). Comparison with ILE-based composite electrolytes with solid and mesoporous oxide particles will be made, showing that enhancement exist only in the monolith structures and not in the particle systems where percolation limits the conductivity.

The influence of drying and calcination on surface chemistry, pore structure and mechanical properties of hierarchically organized porous silica monoliths

Abstract Hierarchically organized, porous materials exhibit unique combinations of physical and chemical properties depending on their pore sizes, pore structure and surface chemistry. Extraction and drying methods as well as post synthetic thermal treatments influence the characteristics of the resulting porous network and thus the achievable properties. Here we present a comprehensive investigation of the effects of drying conditions and post synthesis treatments on surface chemistry, pore structure and resulting mechanical properties of hierarchically structured silica monoliths comprising pores on three hierarchy levels (micro-, meso- and macropores). Samples were either dried supercritically (SCD) with carbon dioxide or at ambient pressure (APD) after surface silylation. In addition, the impact of a post synthetic heat treatment at two different temperatures (300 °C and 500 °C) is investigated. The focus of the study is on chemical and structural changes in/at the (meso-)pore walls, including the presence of micropores and the influence of organic components on the macroscopic properties. We discuss the implications of these modifications on mechanical properties, such as their deformation behavior during fluid adsorption related to their respective bulk and skeletal Young's moduli. Scanning electron microscopy, nitrogen adsorption/desorption measurements, simultaneous thermal analysis, solid-state NMR spectroscopy, small-angle X-ray scattering, sound velocity measurements and nitrogen adsorption/desorption with in-situ dilatometry were performed on each sample. This set of data illustrates the significant impact of different fabrication steps such as drying or calcination on material properties.

Multicatalysis Combining 3D-Printed Devices and Magnetic Nanoparticles in One-Pot Reactions: Steps Forward in Compartmentation and Recyclability of Catalysts

A tricatalytic compartmentalized system that immobilizes metallic species to perform one-pot sequential functionalization is described: a three-dimensional (3D)-printed palladium monolith, ferritic copper(I) magnetic nanoparticles, and a 3D-printed polypropylene capsule-containing copper(II) loaded onto polystyrene-supported 1,5,7-triazabicyclo[4.4.0]dec-5-ene (PS-TBD) allowed the rapid synthesis of diverse substituted 1-([1,1'-biphenyl]-4-yl)-1H-1,2,3-triazoles. The procedure is based on the Chan-Lam azidation/copper alkyne-azide cycloaddition/Suzuki reaction strategy in the solution phase. This catalytic system enabled the efficient assembly of the final compounds in high yields without the need for special additives or intermediate isolation. The monolithic catalyst-containing immobilized palladium species was synthesized by surface chemical modification of a 3D-printed silica monolith using a soluble polyimide resin as a key reagent, thus creating an extremely robust composite. All three immobilized catalysts described here were easily recovered and reused in numerous cycles. This work exemplifies the role of 3D printing in the design and manufacture of devices for compartmented multicatalytic systems to carry out complex one-pot transformations.

A flow-based platform hyphenated to on-line liquid chromatography for automatic leaching tests of chemical additives from microplastics into seawater

An automatic flow-based system as a front end to liquid chromatography (LC) for on-line dynamic leaching of microplastic materials (polyethylene of medium density and poly(vinyl chloride)) with incurred phthalates and bisphenol A is herein presented. The microplastic particles were packed in a metal column holder, through which seawater was pumped continuously by resorting to advanced flow methodology. Each milliliter of the leachable (bioaccessible) fraction of chemical additives was preconcentrated on-line using a 10 mm-long octadecyl monolithic silica column placed in the sampling loop of the injection valve of a HPLC system that served concomitantly for analyte uptake and removal of the seawater matrix. After loading of the leachate fraction, the LC valve was switched to the inject position and the analytes were eluted and separated by a monolithic column (Onyx C18HD 100 × 4.6 mm) using an optimized acetonitrile/water gradient with UV detection at 240 nm. The automatic flow method including dynamic flow-through extraction, on-line sorptive preconcentration, and matrix clean-up was synchronized with the HPLC separation, which lasted ca. 9 min.The only two currently available multi-component certified reference materials (CRM) of microplastics (CRM-PE002 and CRM-PVC001) were used for method development and validation. Out of the eight regulated phthalates contained in the two CRMs, only the 2 most polar species, namely, dimethyl phthalate and diethyl phthalate as well as bisphenol A, were leached significantly by the seawater in less than 2 h, with bioaccessibility percentages of 51–100%. The leaching profiles were monitored and modeled with a first-order kinetic equation so as to determine the rate constants for desorption in a risk assessment scenario. Intermediate precision values of bioaccessibility data for three batches of CRMs were for the suite of targeted compounds ≤22%.This work for the first time reports a fully automatic flow method with infinite sink capacity (i.e., using a surplus of extracting solution) for the target species able to mimic the leaching of additives from plastic debris across the water body in marine settings under worst-case extraction conditions.

Styrene-N-phenylacrylamide co-polymer modified silica monolith particles with an optimized mixing ratio of monomers as a new stationary phase for the separation of peptides in high performance liquid chromatography.

A stationary phase was prepared by chemical derivatization of the support particles with a layer of copolymer composed of styrene and N-phenyl acrylamide. Silica monolith particles of ca. 2.6µm (volume-based average) have been prepared as the support particles by sol-gel reaction followed by differential sedimentation. The particles were reacted with 3-chloropropyl trimethoxysilane followed by sodium diethyldithiocarbamate to introduce an initiator moiety. Then, the copolymer layer was immobilized via reversible addition-fragmentation transfer polymerization. The resultant phase was packed in glass-lined stainless-steel micro-columns (1 x 150mm) and evaluated for the separation of a mixture composed of five peptides (Trp-Gly, Thr-Tyr-Ser, angiotensin I, isotocin and bradykinin). The effect of monomer mixing ratio (styrene versus N-phenyl acrylamide) on the chromatographic separation efficiency of the stationary phase was examined. A number of theoretical plates (N) as high as 33600 plates/column (224000 plates/m, 4.46µm plate height) was achieved using the column packed with the optimized stationary phase. The column-to-column reproducibility based on three columns packed with three different batches of stationary phase was found satisfactory in separation efficiency, retention factor, and asymmetry factor.

Isolation of intact bacteria from blood by selective cell lysis in a microfluidic porous silica monolith

Rapid and efficient isolation of bacteria from complex biological matrices is necessary for effective pathogen identification in emerging single-cell diagnostics. Here, we demonstrate the isolation of intact and viable bacteria from whole blood through the selective lysis of blood cells during flow through a porous silica monolith. Efficient mechanical hemolysis is achieved while providing passage of intact and viable bacteria through the monoliths, allowing size-based isolation of bacteria to be performed following selective lysis. A process for synthesizing large quantities of discrete capillary-bound monolith elements and millimeter-scale monolith bricks is described, together with the seamless integration of individual monoliths into microfluidic chips. The impact of monolith morphology, geometry, and flow conditions on cell lysis is explored, and flow regimes are identified wherein robust selective blood cell lysis and intact bacteria passage are achieved for multiple gram-negative and gram-positive bacteria. The technique is shown to enable rapid sample preparation and bacteria analysis by single-cell Raman spectrometry. The selective lysis technique presents a unique sample preparation step supporting rapid and culture-free analysis of bacteria for the point of care.

Harnessing Heat Beyond 200 °C from Unconcentrated Sunlight with Nonevacuated Transparent Aerogels

Heat at intermediate temperatures (120-220 °C) is in significant demand in both industrial and domestic sectors for applications such as water and space heating, steam generation, sterilization, and other industrial processes. Harnessing heat from solar energy at these temperatures, however, requires costly optical and mechanical components to concentrate the dilute solar flux and suppress heat losses. Thus, achieving high temperatures under unconcentrated sunlight remains a technological challenge as well as an opportunity for utilizing solar thermal energy. In this work, we demonstrate a solar receiver capable of reaching over 265 °C under ambient conditions without optical concentration. The high temperatures are achieved by leveraging an artificial greenhouse effect within an optimized monolithic silica aerogel to reduce heat losses while maintaining high solar transparency. This study demonstrates a viable path to promote cost-effective solar thermal energy at intermediate temperatures.

Solid Nano-Composite Electrolytes (nano-SCE) with Ion Conductivity Promotion at an Interfacial Ice Layer on the Mesoporous Silica Matrix

The transition to solid-state Li-ion batteries requires solid electrolytes with Li-ion conductivity exceeding 1 mS/cm. Solid composite electrolytes or SCEs consisting of an ionic conductor and a dielectric matrix offers an elegant strategy to enhance the ionic conductivity of electrolytes by engineering the interface conduction. Composite electrolyte materials with inorganic oxide matrixes such as silica, alumina or titania with, for example, inorganic or polymer electrolytes have indeed shown enhancements in ion conductivity, however, the total ion conductivity was still well below 1mS/cm due to the low conductivity of the starting individual electrolytes used. Also composites of mesoporous oxide matrix filled with non-volatile ionic liquid electrolyte (ILE) fillers have been explored as solid electrolyte option. The advantage is that ILE can already have quite high ionic conductivity as individual electrolyte component. However, simple confinement of an electrolyte solution in nanometer size pores results in lower conductivity as its effective viscosity increases. The decrease in ion conductivity is expected the worse for mesoporous channels (~10nm in diameter) where the ionic liquid can even turn solid. To achieve higher ion conductivity, interface enhancement has to exceed the decrease in conductivity by confinement. Monolithic nanoporous silica with ILE confined in the porous structures, also named “ionogels” have shown ion conductivities approaching that of the ILE bulk conductivity, indeed, indicating the presence of interface enhancement in these materials. However, so far, the ionic conductivity of the confined ILE in the nanoporous oxide has never exceeded that of the ILE conductivity itself. These ionogels are fabricated by a sol-gel process e.g. by hydrolysis-condensation reaction with tetra-ethylorthosilicate (TEOS) precursor and typically formic acid where the ILE is added in the solution as the template for the silica to grow around. In this paper we demonstrate that the Li-ion conductivity of nano-composites consisting of a mesoporous silica monolith with an ionic liquid electrolyte as filler can be several times higher than that of the pure ionic liquid electrolyte itself when the silica surface is appropriately hydroxylated. Interfacial ice layers induce strong adsorption and ordering of the ionic liquid molecules through H-bonding rendering it immobile and solid-like as for the interfacial ice layer itself. The dipole over the adsorbate results in solvation of the Li+ ions for enhanced conduction. The existence of an interfacial mesophase layer is proven by Infrared and Raman spectroscopy. Higher Li-ion diffusion coefficients for the nanocomposite compared to the pure ionic liquid electrolyte reference is shown by Pulsed-Field-Gradient NMR. The principle of ion conduction enhancement is generic and could be applied to different ion systems. The concept also allows for further (nano)engineering towards specific properties of ion conduction, transport number, electrochemical window, safety and cost for future battery cell generations. The nano-SCE was fabricated in a similar way as the ionogels: a single-step sol-gel process with a TEOS precursor and with the ionic liquid electrolyte in the homogeneous precursor solution, except we did not use formic acid but water. We will focus on systematic study of our nano-SCE model system with (N-butyl- N-methyl pyrrolidinium bis(trifluoromethanesulfonyl) imide ([BMP]TFSI) and bis(trifluoromethanesulfonyl)imide lithium salt (LiTFSI). Figure caption: Ball-and-stick model for the adsorbed mesophase layer on silica with an interfacial ice water layer. The strong H-bonding between TFSI anions and OH surface groups result in polarization of the adsorbed ILE layer and the dissociation of Li+ from TFSI- anion. The free Li-ions can move faster through the liquid-like layer just above the adsorbed mesophase layer resulting in enhanced ion conductivity. Figure 1

Solid-State Lithium and Li-Ion Batteries with Silica-Gel Solid Nanocomposite Electrolytes

The transition to solid-state Li-ion batteries requires solid electrolytes with Li-ion conductivity exceeding 1 mS/cm. Solid composite electrolytes or SCEs consisting of an ionic conductor and a dielectric matrix offers an elegant strategy to enhance the ionic conductivity of electrolytes by engineering the interface conduction. At imec, we have developed a ternary nano-composite electrolyte composed of a non-volatile ionic liquid and organic Li-salt confined in mesoporous silica. The material is made by a one-step sol-gel process whereby the ionic liquid acts as template for the hydrolysis and polycondensation reaction leading to an aqueous gel. The process is similar to that for ionogels with that difference that no acid is used but water. The water and solvents are subsequently carefully removed to form a solid nano-composite electrolyte. The slow sol-gel reaction and drying allows the adsorption of an ordered molecular layer on the fully hydrolyzed silica surface. In this way, several nano-SCE with conductivities between 0.3 and 3 mS/cm have been synthesized, using TFSI-based ionic liquid electrolytes (ILE). We demonstrate that the Li-ion conductivity of nano-composites consisting of a mesoporous silica monolith with an ionic liquid electrolyte as filler can be several times higher than that of the pure ionic liquid electrolyte itself when the silica surface is appropriately hydroxylated. Interfacial ice layers induce strong adsorption and ordering of the ionic liquid molecules through H-bonding rendering it immobile and solid-like as for the interfacial ice layer itself. The dipole over the adsorbate results in solvation of the Li+ ions for enhanced conduction. We will show that the ice layer is electrochemically inactive, in contrast with water-in-salt electrolytes. Functional cells with LFP, LMO and NCA cathodes with Li, Li-alloy and LTO electrodes are demonstrated. As the ice-water layer was confirmed to be electrochemically inactive, it doesn’t cause degradation during cycling of the batteries. Furthermore, damage to the active electrode materials is avoided as our water-based sol-gel precursor does not contain corrosive acid compounds such as formic acid typically proposed as catalyst in literature. The cells are made by impregnation of the liquid sol-gel precursor solution inside the porous electrodes, very similar to how liquid cells are made. The sol-gel reaction and solidification is done in-situ inside the electrodes. By careful drying, the nano-SCE contracts the electrodes together and the electrolyte fills the spaces in the porous electrodes, providing an all around contact with the active material. As such, we have shown high capacity cells at C-rates up to 0.5C. C-rate and cycling performance of the solid-state cells with nano-SCE is shown. Figure caption: Functionality of nano-SCE as Li-ion electrolyte up to 4.3V: galvanic charge/discharge curves of Li/nano-SCE/ LiMn2O4 cell for 5 cycles at each C-rate of 1 C, 5 C, and 20 C. Figure 1

Mesoporous composite material for efficient lead(II) detection and removal from aqueous media

A novel ligand based conjugate material (CMA) was prepared for toxic lead (Pb(II)) ion monitoring and removal from aqueous solution. The organic ligand of 6-((2-(2-hydroxy-1-naphthoyl)hydrazono)methyl)benzoic acid was successfully synthesized and then anchored onto the porous silica monolith. The CMA was enhanced the color upon addition of Pb(II) ion and the results were the evident of the one-step monitoring of wide-range Pb(II) concentrations without using the highly sophisticated apparatus, and this was unique feature of the CMA. The limit of detection was 0.42 μg/L, which was the lower than the permissible limit in drinking water. Varying factors that may affect the Pb(II) removal efficiency such as solution pH, reaction time and coexistent metal ions were systematically investigated. The data was clarified that the developed CMA was removed more than 99% of Pb(II) ion from aqueous solution under the optimum experimental protocol. The maximum adsorption capacity for CMA was 196.35 mg/g. The adsorption data were well fitted to the Langmuir isotherm model and confirmed the monolayer coverage as desired from the CMA morphology. The CMA was exhibited the high affinity to the Pb(II) in the presence of high concentration competing ion. In addition, the adsorbed Pb(II) was desorbed from the CMA with stripping agent (0.10 M HCl) and simultaneously regenerated into an initial form for the next monitoring and removal operations after washing with water. Based on the experiment results, it is concluded that the CMA is highly sensitive and selective material for efficient water treatment for supplying the pure drinking water.

Stable Immobilization of Enzymes in a Macro- and Mesoporous Silica Monolith.

Horseradish peroxidase isoenzyme C (HRP) and Engyodontium album proteinase K (proK) were immobilized inside macro- and mesoporous silica monoliths. Stable immobilization was achieved through simple noncovalent adsorption of conjugates, which were prepared from a polycationic, water-soluble second generation dendronized polymer (denpol) and the enzymes. Conjugates prepared from three denpols with the same type of repeating unit (r.u.), but different average lengths were compared. It was shown that there is no obvious advantage of using denpols with very long chains. Excellent results were achieved with denpols having on average 750 or 1000 r.u. The enzyme-loaded monoliths were tested as flow reactors. Comparison was made with microscopy glass coverslips onto which the conjugates were immobilized and with glass micropipettes containing adsorbed conjugates. High enzyme loading was achieved using the monoliths. Monoliths containing immobilized denpol–HRP conjugates exhibited good operational stability at 25 °C (for at least several hours), and good storage stability at 4 °C (at least for weeks) was demonstrated. Such HRP-containing monoliths were applied as continuous flow reactors for the quantitative determination of hydrogen peroxide in aqueous solution between 1 μM (34 ng/mL) and 50 μM (1.7 μg/mL). Although many methods for immobilizing enzymes on silica surfaces exist, there are only a few approaches with porous silica materials for the development of flow reactors. The work presented is a promising contribution to this field of research toward bioanalytical and biosynthetic applications.