Browse
Submit Data
Databases
API
Help

Dataset Information

23 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

A facile template route to periodic mesoporous organosilicas nanospheres with tubular structure by using compressed CO₂.

ABSTRACT: Periodic mesoporous organosilicas (PMOs) nanospheres with tubular structure were prepared with compressed CO₂ using cationic and anionic mixed surfactant (CTAB/SDS) and triblock copolymer Pluronic P123 as bi-templates. TEM, N₂ adsorption-desorption, solid NMR, and FTIR were employed to characterize the obtained materials. Compressed CO₂ severed as acidic reagent to promote the hydrolysis of organosilicas, and could tune the morphology and structure of the obtained PMOs nanomaterials simple by adjusting the CO₂ pressure during the synthesis process. Rhodamine B (RB) and Ibuprofen (IBU), as the model dye and drug, were loaded into the prepared nanomaterials to reveal its adsorption and desorption ability. Furthermore, different molars of the surfactant (CTAB/SDS) and organosilane precursor (BTEB) were investigated to show the effect of the surfactant concentration on the morphology and structure of the PMOs prepared with compressed CO₂, and some different structures were obtained. A possible mechanism for the synthesis of PMOs with tubular structure using compressed CO₂ was proposed based on the experimental results.

SUBMITTER: Huang X

PROVIDER: S-EPMC5357914 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Site-isolated manganese carbonyl on bipyridine-functionalities of periodic mesoporous organosilicas: efficient CO2 photoreduction and detection of key reaction intermediates.

Project description:Well-defined and fully characterized supported CO2 reduction catalysts are developed through the immobilization of an earth abundant Mn complex on bpy-PMO (bpy = bipyridine; PMO = Periodic Mesoporous Organosilica) platform materials. The resulting isolated Mn-carbonyl centers coordinated to bipyridine functionalities of bpy-PMO catalyze the photoreduction of CO2 into CO and HCOOH with up to ca. 720 TON in the presence of BIH (1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzoimidazole), used as the electron donor. A broad range of photochemical conditions (varying solvents, sacrificial electron donors, photosensitizer type and concentration, catalyst loading as well as the Mn loading within the PMO) are investigated, demonstrating high activity even for simple organic dyes and Zn-porphyrin as photosensitizers. Spectroscopic and catalytic data also indicate that site isolation of the Mn complex in the PMO framework probably inhibits bimolecular processes such as dimerisation and disproportionation and thus allows the spectroscopic observation of key reaction intermediates, namely the two meridional isomers of the carbonyl complexes and the bipyridine radical anion species.

| S-EPMC5857931 | biostudies-literature

Soft-Template Synthesis of Mesoporous Anatase TiO? Nanospheres and Its Enhanced Photoactivity.

Project description:Highly crystalline mesoporous anatase TiO? nanospheres with high surface area (higher than P25 and anatase TiO?) are prepared by a soft-template method. Despite the high specific surface area, these samples have three times lower equilibrium adsorption (<2%) than Degussa P25. The rate constant of the mesoporous anatase TiO? (0.024 min-1) reported here is 364% higher than that of P25 (0.0066 min-1), for the same catalytic loading. The results of oxidation-extraction photometry using several reactive oxygen species (ROS) scavengers indicated that mesoporous anatase TiO? generates more ROS than P25 under UV-light irradiation. This significant improvement in the photocatalytic performance of mesoporous spherical TiO? arises from the following synergistic effects in the reported sample: (i) high surface area; (ii) improved crystallinity; (iii) narrow pore wall thicknesses (ensuring the rapid migration of photogenerated carriers to the surface of the material); and (iv) greater ROS generation under UV-light.

| S-EPMC6150209 | biostudies-literature

A novel route for preparation of hollow carbon nanospheres without introducing template.

Project description:UNLABELLED:A newly developed route for the synthesis of hollow carbon nanospheres without introducing template under hydrothermal conditions was reported. Hollow carbon nanospheres with the diameter of about 100 nm were synthesized using alginate as reagent only. Many instruments were applied to characterize the morphologies and structures of carbon hollow nanospheres, such as XRD, TEM, and Raman spectroscopy. The possible formation and growth mechanism of carbon hollow spheres were discussed on the basis of the investigation of reaction influence factors, such as temperature, time, and content. The findings would be useful for the synthesis of more materials with hollow structure and for the potential use in many aspects. The loading of SnO(2) on the surface of carbon hollow spheres was processed, and its PL property was also characterized. ELECTRONIC SUPPLEMENTARY MATERIAL:The online version of this article (doi:10.1007/s11671-009-9406-7) contains supplementary material, which is available to authorized users.

| S-EPMC2894182 | biostudies-literature

Synthesis and Characterization of Novel Pyridine Periodic Mesoporous Organosilicas and Its Catalytic Activity in the Knoevenagel Condensation Reaction.

Project description:The preparation of novel organic-inorganic hybrid mesoporous organosilica containing pyridinedicarboxamide functional groups uniformly distributed inside the nanostructured pore walls has been addressed. The mesoporosity and uniformity of the synthesized nanomaterials were characterized by different techniques such as nitrogen adsorption/desorption measurements and powder X-ray diffraction (PXRD). Additionally, the presence of the pyridinedicarboxamide in the pore walls of the nanomaterials was assessed by Fourier-transform infrared spectroscopy (FT-IR), as well as 29Si and 13C solid-state cross-polarization and magic angle spinning nuclear magnetic resonance (CP/MAS-NMR). The Knoevenagel condensation of aldehydes with active methylene compounds was carried out over the pyridinedicarboxamide functionalized mesoporous organosilica, which has been proven to be an efficient heterogeneous basic catalyst in the presence of ethanol as solvent. The catalytic activity of the investigated materials was investigated in the Knoevenagel condensation between malononitrile and several benzaldehyde derivatives exhibiting a high conversion (>90%) and excellent selectivity toward the final condensation products under very mild reaction conditions. Furthermore, the catalyst stability is noteworthy as it could be recycled and reused at least twelve times without any significant change in the performance.

| S-EPMC7084680 | biostudies-literature

Pseudocapacitance of Mesoporous Spinel-Type MCo2O4 (M = Co, Zn, and Ni) Rods Fabricated by a Facile Solvothermal Route.

Project description:We present the structural properties and electrochemical capacitance of mesoporous MCo2O4 (M = Co, Zn, and Ni) rods synthesized by a facile solvothermal route without necessity to use templates. The Brunauer-Emmett-Teller specific surface areas of these mesoporous rods are found to be about 24, 54, and 62 m2 g-1 with major pore diameters of about 31, 15, and 9 nm for MCo2O4, M = Co, Zn, and Ni, respectively. X-ray photoelectron spectroscopy and X-ray diffraction studies reveal the phase purity of the samples with a predominant spinel-type crystal structure. The spinel crystal structure with lattice parameters of 8.118, 8.106, and 8.125 Å is obtained for MCo2O4, M = Co, Zn, and Ni, respectively. The transmission electron microscopy study reveals that the mesoporous rods are built by self-assembled aggregates of nanoparticles which are well-interconnected to form stable mesoporous rods. The electrochemical capacitor performance was investigated by means of cyclic voltammetry, galvanostatic charge/discharge cycling, and impedance spectroscopy in a three-electrode configuration. As a result, the spinel-type MCo2O4 rods exhibit high specific capacitances of 1846 F g-1 (CoCo2O4), 1983 F g-1 (ZnCo2O4), and 2118 F g-1 (NiCo2O4) at a scan rate of 2 mV/s. Furthermore, the mesoporous spinel-type metal oxides show desirable stability in alkaline electrolyte during long-term cycling with excellent cycling efficiency.

| S-EPMC6644350 | biostudies-literature

Preparation of Palladium-Supported Periodic Mesoporous Organosilicas and their Use as Catalysts in the Suzuki Cross-Coupling Reaction.

Project description:Three periodic mesoporous materials, i.e., two organosilicas with either ethylene or phenylene bridges and one silica, have been used as supports for Pd nanoparticles. All Pd-supported samples (1.0 wt%) were prepared by the incipient wetness method and subsequently reduced in an H₂ stream at 200 °C. Both hydrogen chemisorption and temperature programmed reduction experiments revealed significant differences depending on the support. Pd2+ species were more reducible on the mesoporous organosilicas than on their silica counterpart. Also, remarkable differences on the particle morphology were observed by transmission electron microscopy. All Pd-supported samples were active in the Suzuki cross-coupling reaction between bromobenzene and phenylboronic acid.

| S-EPMC5452325 | biostudies-other

Dual metal nanoparticles within multicompartmentalized mesoporous organosilicas for efficient sequential hydrogenation.

Project description:Controlling localization of multiple metal nanoparticles on a single support is at the cutting edge of designing cascade catalysts, but is still a scientific and technological challenge because of the lack of nanostructured materials that can not only host metal nanoparticles in different sub-compartments but also enable efficient molecular transport between different metals. Herein we report a multicompartmentalized mesoporous organosilica with spatially separated sub-compartments that are connected by short nanochannels. Such a unique structure allows co-localization of Ru and Pd nanoparticles in a nanoscale proximal fashion. The so designed cascade catalyst exhibits an order of magnitude activity enhancement in the sequential hydrogenation of nitroarenes to cyclohexylamines compared with its mono/bi-metallic counterparts. Crucially, an interesting phenomenon of neighboring metal-assisted hydrogenation via hydrogen spillover is observed, contributing to the significant enhancement in catalytic efficiency. The multicompartmentalized architectures along with the revealed mechanism of accelerated hydrogenation provide vast opportunity for designing efficient cascade catalysts.

| S-EPMC8371113 | biostudies-literature

Double Phosphinoboration of CO2 : A Facile Route to Diphospha-Ureas.

Project description:The reactions of CO2 with a series of phosphinoboranes, including R2 PBpin (R=Ph, tBu; pin=pinacol), R2 PBMes2 (R=Ph, tBu; Mes=2,4,6-Me3 -C6 H2 ), and R2 PBcat (R=Ph, tBu, Mes; cat=catechol) are described. Although R2 PBpin and R2 PBMes2 afford products of the form R2 PCO2 Bpin (R=Ph 1, tBu 4) and R2 PCO2 BMes2 (R=Ph 2, tBu 3), respectively, R2 PBcat lead to further reaction affording the diphospha-ureas, (R2 P)2 CO (R=Ph 5, tBu 6, Mes 7), together with O(Bcat)2 . Computational studies provide insight into the mechanism, revealing an intermediate derived from double phosphinoboration of CO2 .

| S-EPMC6916295 | biostudies-literature

Periodic Mesoporous Organosilica Nanoparticles for CO2 Adsorption at Standard Temperature and Pressure.

Project description:(1) Background: Due to human activities, greenhouse gas (GHG) concentrations in the atmosphere are constantly rising, causing the greenhouse effect. Among GHGs, carbon dioxide (CO2) is responsible for about two-thirds of the total energy imbalance which is the origin of the increase in the Earth's temperature. (2) Methods: In this field, we describe the development of periodic mesoporous organosilica nanoparticles (PMO NPs) used to capture and store CO2 present in the atmosphere. Several types of PMO NP (bis(triethoxysilyl)ethane (BTEE) as matrix, co-condensed with trialkoxysilylated aminopyridine (py) and trialkoxysilylated bipyridine (Etbipy and iPrbipy)) were synthesized by means of the sol-gel procedure, then characterized with different techniques (DLS, TEM, FTIR, BET). A systematic evaluation of CO2 adsorption was carried out at 298 K and 273 K, at low pressure. (3) Results: The best values of CO2 adsorption were obtained with 6% bipyridine: 1.045 mmol·g-1 at 298 K and 2.26 mmol·g-1 at 273 K. (4) Conclusions: The synthetized BTEE/aminopyridine or bipyridine PMO NPs showed significant results and could be promising for carbon capture and storage (CCS) application.

| S-EPMC9268279 | biostudies-literature

Tuning molecular adsorption in SBA-15-type periodic mesoporous organosilicas by systematic variation of their surface polarity† †Electronic supplementary information (ESI) available. See DOI: 10.1039/d0sc00168f

Project description:Adsorption of organic molecules from solution into mesoporous organosilicas is modulated by the relative polarity of the surface. Surface polarity plays a key role in controlling molecular adsorption at solid–liquid interfaces, with major implications for reactions and separations. In this study, the chemical composition of periodic mesoporous organosilicas (PMOs) was varied by co-condensing Si(OEt)4 with organodisilanes, to create a homologous series of materials with similar surface areas, pore volumes, and hydroxyl contents. Their relative surface polarities, obtained by measuring the fluorescence of a solvatochromic dye, cover a wide range. In this series of PMO materials, EPR spectra of tethered nitroxide radicals show monotonically decreasing mobility as larger fractions of the radicals interact strongly with increasingly non-polar surfaces. The surface properties of the materials also correlate with their affinities for organic molecules dissolved in various solvents. The most polar PMO has negligible affinity for phenol, p-cresol, or furfural when these molecules are dissolved in water. However, stronger solute–surface interactions and favor adsorption as the surface polarity decreases. The trend is reversed for furfural in benzene, where weaker solvent–surface interactions result in higher adsorption on polar surfaces. In DMSO, furfural adsorption is suppressed due to the similar strengths of solute-surface and solvent–surface interactions. Thus, the polarity of the surface relative to the solvent is critical for molecular adsorption. These findings show how adsorption/desorption can be precisely and systematically tuned by appropriate choice of both solvent and surface, and contribute to a predictive strategy for the design of catalytic and separations processes.

| S-EPMC7643544 | biostudies-literature