Template Precursor Research Articles

Ni-SBA-15 Catalysts for Production of Hydrogen and Carbon Nanotubes

Thermo Catalytic Decomposition of Methane Using Ni/SBA-15 catalyst was tested in a fixed bed reactor to simultaneously produce hydrogen and carbon nanotubes. SBA-15 nano catalysts were successfully been synthesized using p123, tetraethyl orthosilicate and Ni(NO3)2.6H2O as template, silica source and Nickel nano particle precursors respectively under acidic hydrothermal conditions. The BET surface area, pore size distribution and low angle X-ray Diffraction (XRD) studies revealed that the retention of hexagonally ordered behavior in the catalysts. Wide angle XRD study divulged the crystalline behavior of Nickel oxide species and these Nickel oxide species are in nano range. The catalytic activity experiments were preceded by blank tests intended to ascertain that the reaction did not take place to an appreciable extent in the absence of the catalyst. With SBA-15 alone and Ni alone reaction has not been taken place. Even with 50Ni-SBA-15 and 70Ni-SBA-15 catalysts reaction was not occurred. Only low loading Ni-SBA-15 catalyst was found to be active towards the conversion of methane into the corresponding hydrogen. Among all other catalysts, 30Ni-SBA-15 we observed to produce high yield of hydrogen produced 20% to 50% of H2 at a moderate temperature of 1123K (850°C) and the catalytic activity of the catalyst remains stable for 5hrs. Carbon nanotubes were formed, due to the weak interaction between the metallic nickel and the support. Most of the nickel particles are located on the tip of the produced carbon nanotubes, which avoids rapid deactivation of the catalyst resulted from carbon encapsulation.

MOF-directed templating synthesis of a porous multicomponent dodecahedron with hollow interiors for enhanced lithium-ion battery anodes

A NiCo2O4/NiO-HD nanocage is synthesized using MOF as a precursor and self-sacrificing template. A lithium-ion battery anode based this novel nanomaterial exhibits outstanding capacity, cycling stability and rate performance.

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Rapid chemical transformation from micelle templated precursors (metal nitrate and citric acid) to ordered mesoporous metal carbonates and oxides is demonstrated using microwave heating for cobalt, copper, manganese and zinc. Without aging requirements, <3 min of microwave processing yields highly ordered mesoporous films.

Fabrication of molecularly cholesterol-imprinted polymer particles based on chitin and their adsorption ability

Molecularly imprinted polymers (MIPs) are new materials for molecular identification ability with specific identification, preordainment, and wide applicability. A cholesteryl chitin carbonate (Chol-Chi) was synthesized via two steps, and its chemical structure was characterized by Fourier transform infrared spectroscopy and solid-state 13C nuclear magnetic resonance. The resulting Chol-Chi was used as a covalently bound template precursor for imprinting cholesterol. After this precursor was cross-linked with toluene-2,4-diisocyanate, the carbonate bond in the cross-linked Chol-Chi obtained was cleaved hydrolytically to afford a guest-binding site accompanying the easy and efficient removal of a sacrificial spacer. Field emission scanning electron micrograph observation showed that the surface on MIP particles was rough and porous. The equilibrium adsorption capacity for the molecularly cholesterol-imprinted polymer (Chol-MIP) was 13.60 mg/g, while that of the cholesterol-non-imprinted polymer (Chol-NIP) was only 4.75 mg/g when concentrations of the MIP and NIP equaled to 20.0 mg, respectively. Reusability of Chol-MIP with negligible loss of the initial adsorption capacity was observed after five adsorption–desorption cycles. In addition, stigmasterol and estradiol were selected as competitive molecules in selectivity tests, and the MIPs showed a good specific selectivity and intense recognition of cholesterol.

Structure property relationship of metal matrix syntactic foams manufactured by a binder jet printing process

The present research work has investigated the synthesis of ceramic structures based on inorganic, spherical-hollow microballoons using a binder jet printing process. Binder jet printing is a process that allows the synthesis process of complex and intricate parts with minimal waste of the feedstock material. The ceramic microballoons here investigated were based on a mullite derivative. The printed ceramic parts were cured and sintered as the precursor templates for metal matrix syntactic foams (MMSFs). The MMSFs were manufactured by infiltrating the printed ceramic templates by molten aluminum. The flexural strength of the cured, sintered, and infiltrated structures were also investigated. It is proposed that binder jet printing followed by a sintering and pressureless infiltration process represents an advantageous technology for designing complex MMSF structures.

Effect of withdrawal speed on film thickness and hexagonal pore-array dimensions of SBA-15 mesoporous silica thin film.

Two-dimensional hexagonal mesoporous silica thin films of SBA-15 were synthesized on Si substrates via dip-coating using an evaporation-induced self-assembly process. The effect of the withdrawal speed on the thicknesses, one-dimensional pore alignments, and two-dimensional hexagonal pore arrays of the films was elucidated. Detailed analyses of FE-SEM and TEM images and XRD and XRR patterns of the synthesized thin films clarified that the pore sizes, interplanar spacings, and film thicknesses depend on the withdrawal speed. Furthermore, the same films were synthesized on Si substrates with microtrenches. The local flow of coating solutions around microtrenches affects the pore direction as well as the film thickness. In order to form well-ordered mesoporous silica thin films with large surface areas, it is important to control the synthetic conditions such as the local flow of the coating solutions as well as the physicochemical properties of the silica precursor solutions or template molecules.

Dual template route for the synthesis of hierarchical porous boron nitride

Here, a facile dual templates method for the synthesis of hierarchical porous boron nitride (HPBN) powders is reported. For this purpose, ammonia borane (AB) and polystyrene latex/cetyltrimethyl ammonium bromide (CTAB) were used as BN precursor and inorganic templates, respectively. The as-synthesized material was pyrolyzed at 1150°C in ammonia atmosphere resulting in the formation of white BN powder. The typical N2 sorption analysis demonstrated formation of porous BN with presence of macro/meso and micropores. Transmission electron microscope (TEM) observations revealed the existence of rather uniform macropores with 55–60nm in diameter, as well as wormlike mesopores and micropores extended between macropores walls. X-ray diffraction (XRD) and high resolution TEM (HRTEM) analyses displayed the formation of turbostratic-BN with atomic layer distance of 0.37nm. HPBN powders showed fast adsorption rate of methylene blue (MB) solution and high adsorption capacity of 263.1mgg−1 for MB at room temperature.

Simple synthesis of novel hierarchical porous carbon microspheres and their application to rechargeable lithium-ion batteries

Novel hierarchical porous carbon microspheres (HPCM) with quantities of micropores and mesopores have been prepared by an alcohol-in-oil emulsion technique using thermoplastic phenolic formaldehyde resin (PF) as the carbon source and copper nitrate (CN) as the template precursor. The effects of CN loading content on the morphology and structure of HPCM were investigated. The results showed that, when the mass ratio of PF and CN is 1:4, the HPCM not only can maintain hierarchical porous microsphere structure, but also display high electrochemical performance with a reversible capacity of 585mAhg−1 at a current density of 50mAg−1 and favorable high-rate performance when used as the anode materials for lithium-ion batteries.

The influence of layered double hydroxide composition on the morphology, porosity and capacitive properties of nitrogen-doped carbon materials prepared via chemical vapor deposition

Porous N-doped carbon materials of various morphologies are prepared via chemical vapor deposition (CVD) at 700°C using acetonitrile as carbon and nitrogen source and MgAl, MgCoAl, CoAl layered double hydroxides (LDHs) as template and catalyst precursors. The physicochemical properties of the carbon materials are characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, thermogravimetric analysis, elemental analysis, nitrogen sorption and n-nonane thermodesorption, whereas their electrochemical performance is evaluated in 6M KOH by means of cyclic voltammetry, galvanostatic charging/discharging and electrochemical impedance spectroscopy. The choice of LDHs strongly affects the grain morphology and micropore/mesopore contribution in the synthesized carbon materials, which determines their capacitive performance. The application of Co-free LDHs leads to the carbon material consisting of irregular aggregates of plate-like particles highly doped with nitrogen (9.7wt%) and having high specific surface area (863m2g−1) and high capacitance (130Fg−1). On the other hand, the use of Co-containing LDHs results in the carbon materials predominantly made of carbon nanotubes (grown on metallic Co nanoparticles) less doped with nitrogen (2.4–3.1wt%) and having lower specific surface area (193–225m2g−1) and lower capacitance (15–30Fg−1).

Nano/micro-structured Si/CNT/C composite from nano-SiO2for high power lithium ion batteries

Nano/micro-structured pSi and pSi/CNT particles were synthesized from nano-SiO2 as both a template and silicon precursor via a combination of spray drying and magnesiothermic reduction, followed by a nano-layer carbon coating by chemical vapor deposition to obtain a nano/micro-structured pSi/C and pSi/CNT/C composite. In the hierarchical microstructure of the pSi/CNT/C composite, Si nanoparticles less than 20 nm in size were homogenously dispersed in an electronically conductive and porous network of multiwall carbon nanotubes, which can accommodate the volume changes in Si and improve the structural and conductive stability during repeated cycles leading to excellent electrochemical performance. The pSi/CNT/C presented reversible capacities of ca. 2100 mA h g(-1) at 1 A g(-1) and ca. 1370 mA h g(-1) at a high current rate of 5 A g(-1). Its capacity retention after 100 cycles was 95.5% at 1 A g(-1).

Solid–solid grinding/templating route to magnetically separable nitrogen-doped mesoporous carbon for the removal of Cu2+ ions

N-doped ordered mesoporous carbon materials (NOMC) with 2D hexagonal symmetry structure were synthesized via a facile solid–solid grinding/templating route, in which the ionic liquids (ILs) of 1-cyanoethyl-3-methylimidazolium chloride and SBA-15 were employed as the precursor and hard template, respectively. The as-synthesized NOMC features with a uniform mesoporous size (3.5nm), ropes-like morphology (0.4–1μm in length) and high surface area (803m2/g). The quantitative analysis revealed the nitrogen content on the surface of NOMC is 5.5at%. Magnetic iron nanoparticles were successfully embedded into the carbon matrix by introducing iron chloride to the mixture of SBA-15 and ILs during the synthesis process. The NOMC-Fe composite possessed superior adsorption capacity of Cu2+ ions (23.6mg/g). Kinetic and isothermal analysis demonstrated the strong interactions between Cu2+ ion and the adsorbent. Furthermore, the composite was magnetically separable from solution under an external magnetic field and thus displayed a superior reusability in the recycling test.

Development of templated carbon by carbonisation of sucrose-zeolite composite for hydrogen storage

Summary The templated carbons were synthesised by carbonisation of a zeolite–sucrose composite. The effects of carbonisation temperature and dwelling time on the development of pore structure of templated carbon were investigated. Various characterisation techniques were employed to investigate the structural and topographical properties of template precursor as well as synthesised carbons. The highest total surface area of 1033 m2/g and micropore area of 647 m2/g were obtained for carbon synthesised at 750°C with 3 h dwelling time. It was observed that at lower carbonisation temperature or dwelling time, the surface area and pore volume were lower, which may be attributed to incomplete carbonisation of the sucrose. At higher carbonisation temperature or dwelling time, the decrease in surface area and pore volume could be the result of collapse of the pore structure. Maximum 80% micropore area was observed for the templated carbons depending on the synthesis conditions. The hydrogen uptake of the templated carbons was measured by temperature-programmed desorption at 1 bar pressure and different subzero temperatures. The maximum uptake (0.30 wt%) was obtained at 1 bar and −100°C for templated carbon, having a surface area of 1033 m2/g, prepared at 750°C with 3 h dwelling time. This templated carbon had the highest total surface area as well as micropore area. Copyright © 2014 John Wiley & Sons, Ltd.

Intensification of the electrochemiluminescence of luminol on hollow TiO2 nanoshell-modified indium tin oxide electrodes

Hollow titania nanoshells (HTNSs), which were synthesized by a SiO2 sacrificial template method, were used to intensify the electrochemiluminescence (ECL) of luminol. The size, shell thickness and crystal phase, factors that are important in determining the efficiency, can be controlled by adjusting the template size, precursor concentration and calcination temperature, respectively. The structure of the HTNSs was characterized by transmission electron microscopy, scanning electron microscopy and X-ray diffraction spectroscopy. After structural optimization, the surface of indium tin oxide (ITO)-coated glass was modified with the HTNSs to act as a working electrode for a flow-injection analytical system. The heterostructure demonstrated an ECL emission intensity 150 times higher than that of the bare ITO. The research also revealed that the ECL of luminol on this modified electrode showed a very sensitive response to hydrogen peroxide with a detection limit of 4.6×10−10M. In addition to discussing the intensifying mechanism of luminol ECL by HTNSs, we demonstrate that can be successfully applied to evaluate the gross antioxidant activity of garlic.

Electrochemical sensing platform for L-CySH based on nearly uniform Au nanoparticles decorated graphene nanosheets

In this study, Au nanoparticles decorated graphene nanosheets were prepared using poly(vinylpyrrolidone) (PVP) covalently functionalized graphene oxide and chloroauric acid as template and Au precursor, respectively. Both the density and the size of Au nanoparticles deposited on the surface of graphene could be adjusted by the PVP grafting density. The graphene–Au hybrid nanosheets were then applied to fabricate a highly sensitive l-cysteine (L-CySH) electrochemical sensing platform. The cyclic voltammetry results showed that the modified glassy carbon electrode with graphene–Au hybrid nanosheets exhibited strong catalytic activity toward the electrooxidation of L-CySH. The current exhibited a widely linear response ranging from 0.1 to 24μM with a low detection limit under the optimized conditions. The detection limit of L-CySH could reach as low as 20.5nM (S/N=3). The enhanced electrochemical performance of the fabricated sensor was attributed to the combination of the excellent conductivity of graphene and strong catalytic property of uniform Au nanoparticles.

Effects of copper nitrate addition on the pore property and lithium storage performance of hierarchical porous carbon nanosheets from phenolic resin

Hierarchical porous carbon nanosheets (HPCS) were prepared by using thermoplastic phenolic formaldehyde resin as the carbon source and copper nitrate as the template precursor. The effects of Cu(NO3)2 loading content on the pore property and electrochemical performance of HPCS as anode material for lithium ion batteries were investigated. It was found that, with the addition of Cu(NO3)2, both the specific surface area and mesopore percentage increase. Correspondingly, the electrochemical performances of HPCS electrodes in terms of the specific capacity and rate performance improve for lithium ion batteries. The reasons were deduced and discussed from the view point of different pore size, especially the function of mesopores.

Growth Morphologies of Nanostructured Rutile TiO2

The morphological and structural characteristics of nanostructure rutile TiO2 were investigated by using x-ray diffraction, scanning electron microscopy, electron diffraction, conventional and high resolution transmission electron microscopy. As a product of the precursor template of hydrogen titanate nanofibers, rutile could exhibit forms like tree, sheaf, or bundle. Both the branch and trunk of tree-like rutile have the same growth axis of [001]. The sheaf-like rutile forms while it grows along both [001] and [ $$ 00\bar{1} $$ ] directions. The bundle-like rutile grows along only one [001] direction. Tree-like morphology of nanocrystals rutile is revealed to be controlled by (101) twin structure. Twin formation is a possible mechanism to decrease the density of defects and reduce the system energy as the crystal grows.

Fabrication of magnetic mesoporous carbon and its application for adsorptive removal of 2,4,6-trichlorophenol (TCP) from aqueous solution

Magnetic mesoporous (MMP) carbon has been successfully synthesized by using Fe3O4 NPs, CaCO3 and dopamine as cores, template, and carbon precursor, respectively. The synthetic procedure of MMP carbon is simple, low-cost and involves no organic solvents. The generated MMP carbon has a large surface area and strong magnetism. MMP carbon was used to remove 2,4,6-trichlorophenol (TCP) from water samples. The results show that adsorption equilibrium was observed within 10 h, and the kinetics can be described by a pseudo-second-order kinetic model. TCP adsorption is not affected by ionic strength and increases with temperature and initial concentration. When the TCP initial concentrations are 10 and 100 mg L−1, the adsorption capacities are 117 and 610 mg g−1, respectively, which are much higher than those achieved from other adsorbents. These results indicate that most of the adsorption sites on the MMP carbon are available for TCP due to its relatively large pore size.

Preparation of porous nanocarbons with tunable morphology and pore size from copolymer templated precursors

Porous nanocarbons with tunable morphology and pore size were prepared via the carbonization of polyacrylonitrile containing block copolymers. Retention of the nanostructure of the precursor upon pyrolysis was studied for both thin-film and bulk materials. Morphology-dependent preservation of the resulting nanostructure was observed in the latter case.

Drying of particle-loaded foams for production of porous materials: mechanism and theoretical modeling

Particle-loaded wet foams are appropriate precursors for production of novel porous materials with hierarchical porous structure, ranging from tens of micrometers down to a few nanometers. Such porous materials could be further modified (sintered, impregnated, hydrophobized, etc.) to serve as catalyst supports, porous filters, insulating materials, templates for composite materials, etc. A particular obstacle for the design of such materials is the observed extensive shrinkage during drying of the wet foam precursor. This shrinkage has three important consequences – significant reduction of the size of the final porous material (as compared to the precursor template), significant evolution in the pore size distribution during sample drying, and possible cracking of the material upon drying. The major aims of the current study are (1) to clarify the main mechanism of shrinkage of foams prepared from silica suspensions with high particle concentration, and (2) to describe quantitatively the relation between the properties of the foamed suspension and the final dry porous material obtained from this suspension. The performed experiments and the data interpretation convincingly show that the foamed suspensions shrink until the particle concentration in the foam walls reaches close packing, at which the percolated particle structure is able to resist the high capillary pressures, developed in the process of drying. The volumetric shrinkage of the individual bubbles was found to be equal to that of the macroscopic foam sample. Equations are derived and verified to relate the particle concentration and the bubble fraction in the foam precursor with the final mass density of the obtained porous material and with the degree of shrinkage in the drying process. Three stages of foam drying and shrinking were observed: (1) an induction period with no sample shrinkage, despite the water loss, (2) rapid shrinkage, and (3) final water evaporation at constant volume of the sample. These stages were explained by considering the three basic physical regimes of convective drying of porous materials, as defined by Coussot (European Phys. J. B 15 (2000) 557–566). The equations derived in the current study allow one to design in advance the foam precursors needed to obtain a dry porous material with desired properties.

One-pot synthesis of silver nanoparticle catalysts supported on N-doped ordered mesoporous carbon and application in the detection of nitrobenzene

Ag nanoparticles (Ag NPs) supported on nitrogen-doped ordered mesoporous carbon (N-OMC) were fabricated by one-pot synthesis strategy, in which 2D hexagonally ordered mesoporous SBA-15 and aniline were used as template and carbon precursor, respectively. Furthermore, the as-prepared composite of Ag NPs supported on N-OMC (Ag NPs/N-OMC) as electrochemical sensor towards the reduction of nitrobenzene (NB) was investigated, which displayed high sensitivity, fast response and good stability. The peak current of NB increased linearly with the concentration of NB in the range from 6.62×10−8 to 2.60×10−7mol/L and 7.97×10−7 to 1.12×10−6mol/L, and the low detection limit of 6.61×10−9mol/L (S/N=3) was obtained. Therefore, this work provides a new pathway to design and fabricate novel N-OMC composites, which have unique characteristics and hold numerous applications in the fields of sensors, electrocatalysis and others.