SBA-15 Silica Template Research Articles

Synthesis and properties of new nitrogen-doped nanostructured carbon materials obtained by templating of mesoporous silicas with aminosugars

The negative templating synthesis process has been applied to prepare nanostructured carbon materials with a high nitrogen content. SBA-15 silica template was impregnated with the following carbon precursors: sucrose, glucose and amino-glucose. The structure of the materials was investigated by SAXS, WAXS and TEM. Nitrogen functions were analyzed by XPS and the textural parameters of the carbons were studied by nitrogen and CO 2 adsorption. X-ray and TEM studies confirmed that a pore nanostructure is inherited from the silica templates. XPS analysis showed that the nitrogen content of the materials can be controlled between 2 and 5 wt% and that N atoms are strongly bonded in the carbon structure in heterocycles or nitrile functions. An important result is that these nanostructured carbon materials exhibits interesting textural properties with BET surface areas ranging between 1000 and 1300 m 2 / g . Moreover, the study of the influence of nitrogen on the textural and structural parameters of the resulting carbon materials shows that nitrogen plays an active role during the synthesis process. This observation is also supported by the speciation of nitrogen in the nanostructured carbon materials.

Luminescent properties and characterization of one dimensionalGd2O3:Eu3+ phosphor nano-wire for field emission application

Gd2O3:Eu3+ nano-wire phosphors embedded in SBA-15 silica templates were synthesized using a combinationof the sol–gel method and hydrothermal reactions followed by a sintering process at1000 °C. The crystalstructure of Gd2O3:Eu3+ was confirmed using x-ray diffraction. Observation using transmission electron microscopy showsthat the nano-wire diameters were very uniform in the 7–9 nm range. In comparison with bulkGd2O3:Eu3+ materials, we found that the photo-luminescent property of the nano-wire was different. The analysisshows that the main nano-wire emission peaks were at 585, 597, 613 and 620 nm. The CIE value(x = 0.62,y = 0.38) indicates that the nano-wire emitted a pink colour and not red as for the bulk material.The field emission experimental results agreed well with the photo-luminescent analysisresults.

Simultaneous Control of Morphology and Porosity in Nanoporous Carbon: Graphitic Mesoporous Carbon Nanorods and Nanotubules with Tunable Pore Size

We report on the use of simple chemical vapor deposition (CVD) nanocasting routes to simultaneously control the morphology, pore size, and graphitization in structurally well-ordered mesoporous carbons. Mesoporous silica SBA-15 rods were used as hard templates to nanocast mesostructured carbon nanorods and nanotubules with tunable pore size. The pore size of the carbons was tunable between 2 and 4.5 nm by simply using SBA-15 silica templates synthesized at various temperatures between 40 and 130 °C. Depending on the textural properties (and in particular the pore size) of the SBA-15 silica template, the particle morphology of the mesoporous carbon materials was changeable from nanorods (solid core) to hollow nanotubules. Small-pore SBA-15 silicas resulted in mesoporous carbon hollow tubes (nanotubules), whereas larger-pore silicas yielded solid-core rods. The nature of the SBA-15 silica did not affect the extent of graphitization. Greater levels of graphitization were, however, obtained for carbons prepar...

Simple synthesis of mesoporous carbon with magnetic nanoparticles embedded in carbon rods

Magnetically separable ordered mesoporous carbon containing magnetic nanoparticles embedded in the carbon walls was synthesized using a simple synthetic procedure. The resulting magnetically separable mesoporous carbon was denoted as M-OMC (magnetically separable ordered mesoporous carbon) poly(pyrrole) with residual Fe 2+ ions in the mesoporous channel was converted to carbon material containing superparamagnetic nanoparticles. The size of the magnetic nanoparticles obtained was restricted by the channel size of the SBA-15 silica template, which resulted in the generation of superparamagnetic nanoparticles embedded in the carbon rods. The blocking temperature of M-OMC is 110 K. Pore size and textural property of M-OMC is similar to that of hexagonally ordered mesoporous carbon fabricated using SBA-15 silica as a template. The saturation magnetization of M-OMC is ca. 30.0 emu/g at 300 K, high enough for magnetic separation.

Generalized and Facile Synthesis Approach to N-Doped Highly Graphitic Mesoporous Carbon Materials

The synthesis and characterization of porous graphitic carbon materials via chemical vapor deposition (CVD) using various mesoporous silicas including SBA-12, SBA-15, MCM-48, MCM-41, and HMS as solid templates is presented. The use of acetonitrile as carbon precursor generates N-doped carbon (CNx type) materials with nitrogen content of ca. 8 wt %. The N-doped carbon materials exhibit both well-ordered mesoporosity and high levels of graphitic character. The mesostructural ordering and extent of graphitization depend on the CVD (i.e., carbonization) temperature and the nature of the silica template. In general, higher CVD temperatures (>900 °C) generated high levels of graphitic character but compromised the mesostructural ordering of the carbon materials. The mesostructural ordering of the CNx materials (and replication of pore channel ordering from the silica template) depends on the nature of the mesoporous silica used as solid template. We achieved structural replication and high surface area (440−1000 m2/g) CNx materials from SBA-12, MCM-48, and SBA-15 silica templates. MCM-41 and HMS silicas did not function effectively as templates and generated low surface area (<320 m2/g) CNx materials. The particle morphology of the silica template was in all cases replicated in the carbon materials, and we observed hollow particles for samples prepared at CVD temperature of 1000 °C or higher.

Direct methanol fuel cell Pt–carbon catalysts by using SBA-15 nanoporous templates

A mesoporous carbon structure based on SBA-15 silica template was used as a cathode catalyst support of platinum in the direct methanol fuel cell (DMFC). The inverse carbon replica of the SBA-15 template was synthesized by carbonization of sucrose exhibiting a large surface area, 1300 m 2/g. Introducing platinum clusters on the carbon support, a large surface area, 800 m 2/g, was maintained and the catalytic activation was confirmed by a DMFC single-cell test. The mesoporous carbon structure could be an ideal catalyst support for electrode support materials in DMFC providing favorable hosting morphology for the metallic catalyst clusters and interconnected pore network for a facile transport of feeds and products. The electrical percolation of the interconnected carbon rods also exhibited a great potentiality for the development of novel DMFC catalyst supports.

Comprehensive Structure Analysis of Ordered Carbon Nanopipe Materials CMK-5 by X-ray Diffraction and Electron Microscopy

The structure of ordered mesoporous carbon materials CMK-5 was analyzed in detail by transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis by applying the recently developed continuous density function technique. The materials present two-dimensional (2-D) hexagonally ordered arrays of carbon nanopipes formed within the mesopores of SBA-15 silica templates used for their fabrication. The series of CMK-5 carbons were synthesized by applying the templates of different pore widths and two carbon precursors: furfuryl alcohol and acenaphthene. All the materials were well-ordered, exhibiting five distinct XRD reflections, high nitrogen BET specific surface areas (about 2500 m2/g), and large pore volumes (about 2 cm3/g). TEM analysis and XRD modeling allowed precise determination of the mesostructure characteristics such as the nanopipe diameter, wall thickness, and shape. Around 15% of the space between the nanopipes was found to be occupied by carbon interconnections formed inside the complementary pores of the SBA-15 templates. The structure parameters determined correlated well with the synthesis procedures and were fully consistent with the nitrogen adsorption and thermogravimetric data. The differences in the properties and the formation mechanisms of the materials synthesized by applying furfuryl alcohol and acenaphthene carbon precursors were analyzed based on the whole scope of data obtained.

Synthesis of Mesoporous Carbon-Containing Ferrocene Derivative and Its Electrochemical Property

Abstract Ordered mesoporous carbon-containing ferrocene derivative (Fc-MC) with a hexagonal framework structure has been prepared using a SBA-15 silica template. The electric double-layer capacitance of Fc-MC increases in comparison with that of pure mesoporous carbon.