Generating porosity in metal oxides thin films through introduction of polymer micelles

The generation of porosity in Nb₂O₅ sol–gel films through introduction of polymer micelles of commercially available copolymer Pluronic PE6800 [poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)] was studied using direct observation of film morphology by Transmission Electron Microscopy and indirect calculations of free volume fraction by optical means. Mesoporous Nb₂O₅ films were deposited by the sol–gel and spin-coating methods and templated with aqueous solutions of Pluronic PE6800 with concentrations below and above critical micelle concentration determined by the modified dye solubilization method. The influence of the duration of the postdeposition annealing on total pore volumes was investigated by reflectance measurements and consequent calculation of optical properties and free volume fraction by Bruggeman effective medium theory. The possible application of the films in optical sensing of vapors has been demonstrated through reflectance measurements prior to and after acetone vapors exposure.     

Deposition conditions in tailoring the morphology of highly porous reticular films prepared by electrostatic spray deposition (ESD) technique

Spongy-like reticular structure is a unique morphology fabricated by electrostatic spray deposition (ESD) technique. The effects of solvent, substrate temperature, precursor feeding rate, static electric field strength, and deposition time on tailoring the reticular structure were investigated. Scanning electron microscopy was used to observe the film morphology. MnO_x or LiMn₂O₄ were selected as the model materials. It is found that in addition to the conventional solvent butyl carbitol, other kinds of solvents such as ethylene glycol and propylene glycol can also be used to obtain reticular films at a suitable substrate temperature. Porous films with a low cross-linking degree pore structure can be prepared by increasing precursor feeding rate or decreasing substrate temperature. Increasing the deposition time or the electric field strength helps to obtain reticular films with more homogeneous pore size distribution. In addition, the addition of a high boiling-point solvent in mixed alcohol solvent results in the increase of proper substrate temperature. It is concluded that the fluidity of the spray droplets on the surface of a hot substrate is an important factor to form a reticular film.     

Surface-modified mesoporous silica with ferrocene derivatives and its ultrasound-triggered functionality

Novel ferrocene derivatives designed as gatekeepers were successfully composed on the pore outlet of amino-functionalized mesoporous silica by post-synthesis grafting where the peptide bond of the amine group (-NH₂) of mesoporous silica was linked with the carboxylic acid group (-COOH) of both ends of the ferrocene derivatives. The materials of the amine-functionalized mesoporous silica (NH₂-MS) and ferrocene-functionalized mesoporous silica (Fc-CONH-MS) were characterized using X-ray diffractions (XRD), Fourier-transform infrared (FT-IR), N₂ sorption isotherms, solid-state NMR spectra, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), and UV-vis absorption spectra. The ferrocene attached to the mesoporous silica pore outlet was cleavaged by ultrasound irradiation, which opened the closed-pore outlets, suggesting a possible application for controlled release drug carrier.     

Adsorption studies of thermal stability of SBA-16 mesoporous silicas

Cage-like ordered mesoporous silicas, SBA-16, and ethane-silicas with cubic (Im3m) and (Fm3m) symmetry groups were synthesized with addition of sodium chloride by using tetraethyl orthosilicate (TEOS) as silica precursor, 1,2-bis(triethoxysilyl)ethane (BTESE) as bridged silsesquioxane and poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) triblock copolymer Pluronic F127 (EO₁₀₆PO₇₀EO₁₀₆) as template at low acid concentrations. The resulting samples were subjected to extraction in order to remove the polymeric template. The as-synthesized and extracted materials were calcined in the range of 350-900 °C to determine their thermal stability. Based on the XRD analysis and nitrogen adsorption data such as the BET specific surface area, volume of primary mesopores, pore wall thickness and pore size distributions, the SBA-16 silicas exhibit relatively high thermal stability because their mesostructural ordering was retained even up to 900 °C. However, an increase in the calcination temperature tended to decrease significantly the BET surface area, volumes of primary and complementary pores, and to less extent the pore size and pore wall thickness due to the structural shrinkage. Furthermore, the as synthesized samples subjected to a short extraction with acidic ethanol solution possessed even better thermal stability. On the other hand, calcination at 550 °C of ethane-silicas caused a complete removal of the ethane bridging groups from the periodic mesoporous organosilicas and their calcination above 800 °C led to the partial collapse of the structure.     

Layer by layer growth of silver chloride nanoparticle within the pore channels of SBA-15/SO3H mesoporous silica (AgClNP/SBA-15/SO3K): Synthesis,characterization and antibacterial properties

The growth of silver chloride nanoparticles within the pore channels of functionalized SBA-15 mesoporous was achieved by sequential dipping steps in alternating bath of potassium chloride and silver nitrate under ultrasound irradiation at pH=9. The effects of sequential dipping steps in growth of the AgCl nanoparticles have been studied. The growth and formation of AgCl nanoparticles inside the sulfonated SBA-15 were characterized by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Antibacterial activity of the synthesized materials was investigated against Escherichia coli (E.coli) using the conventional diffusion-disc method. The materials showed high antibacterial activity.     

Effect of the thermal and hydrothermal treatment on textural properties of Zr-MCM-41 mesoporous molecular sieve

Zr-containing mesoporous molecular sieves were synthesized by hydrothermal method using cetyltrimethyl ammonium bromide as a template and sodium silicate and zirconium sulfate as raw materials. The structure and morphology of the synthesized samples were characterized via various physicochemical methods, including X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, solid state nuclear magnetic resonance (²⁹Si MAS-NMR) techniques, thermal gravimetric-differential scanning calorimeter (TG-DSC) and N₂ physical adsorption, respectively. The effect of the different initial ZrO₂:SiO₂ molar ratio, the different thermal treatment temperature and the different hydrothermal treatment time on textural property was investigated. The experimental results reveal that the as synthesized samples possess a typical mesoporous structure of MCM-41. On the other hand, the specific surface area and pore volume of the synthesized Zr-MCM-41 mesoporous molecular sieve decrease with the increase of the amount of zirconium incorporated in the starting material, the rise of thermal treatment temperature and the prolonging of hydrothermal treatment time, the mesoporous ordering becomes poor. Also, when the molar ratio of ZrO₂:SiO₂ in the starting material is 0.1, the mesoporous structure of the Zr-MCM-41 mesoporous molecular sieve still retains after calcination at 750 °C for 3 h or hydrothermal treatment at 100 °C for 6 d, and have specific surface areas of 423.9 and 563.9 m²/g, respectively.     

Synthesis and characterization of molybdenum incorporated mesoporous aluminophosphate

A synthesis of molybdenum incorporated mesoporous aluminophosphate with long-chain n-alkylamine as template material had been prepared under non-aqueous condition. These materials were extensively characterized by using X-ray diffraction (XRD), nitrogen sorption isotherms, nuclear magnetic resonance of ²⁷Al and ³¹P (NMR), inductive coupled plasma (ICP), electron spin resonance (ESR), Fourier transform infrared (FTIR) and thermogravimetric-differential thermal analysis (TG-DTA). Morphology of the materials had been observed by using transmission electron microscope (TEM) that revealed the mesoporous materials possessed wormhole-like structures. Alkaline solvent extraction using n-butylamine/ethanol had been efficiently removed the n-alkylamine from the mesoporous samples which yielded BET surface areas around 550-730 m²/g. BJH analysis showed a narrow pore size distribution which increased with increasing of the carbon chain length of alkylamine (template). Valence state and coordination of the molybdenum in the obtained samples were investigated by using ESR and FTIR where it was found that Mo⁴⁺ and Mo⁶⁺ molybdenum species existed in the molybdenum incorporated mesoporous aluminophosphate in tetrahedral coordination.     

Biosynthesis and magnetic properties of mesoporous Fe3O4 composites

Magnetic Fe₃O₄ materials with mesoporous structure are synthesized by co-precipitation method using yeast cells as a template. The X-ray diffraction (XRD) pattern indicates that the as-synthesized mesoporous hybrid Fe₃O₄ is well crystallized. The Barrett-Joyner-Halenda (BJH) models reveal the existence of mesostructure in the dried sample which has a specific surface area of 96.31 m²/g and a pore size distribution of 8-14 nm. Transmission electron microscopy (TEM) measurements confirm the wormhole-like structure of the resulting samples. The composition and chemical bonds of the Fe₃O₄/cells composites are studied by Fourier transform infrared (FT-IR) spectroscopy. Preliminary magnetic properties of the mesoporous hybrid Fe₃O₄ are characterized by a vibrating sample magnetometer (VSM). The magnetic Fe₃O₄/cells composites with mesoporous structure have potential applications in biomedical areas, such as drug delivery.     

Uniform Mesoporous CoCO3 Nanospindles on Graphite Nanosheets for Highly Efficient Lithium Storage

As anodes for lithium-ion batteries, CoCO₃ has a much higher specific capacity than graphite and can meet the urgent demands of electric vehicles and portable electronics. However, reported CoCO₃ anodes are of micrometer-sized morphology (0.4–10 µm) that severely limits long-term and rate performances (in particular >2.0 A g⁻¹) due to intrinsically low conductivity and high volume expansion. Mesoporous materials have uniform open mesopores to offer sufficient solid/electrolyte contact, rapid Li⁺ transport, and large pore volume. However, it is still challenging to prepare uniform mesoporous CoCO₃ nanostructures. This work reports a urea–NH₄HCO₃–ethylene glycol (EG) solvothermal system to fabricate uniform mesoporous CoCO₃ nanospindles and concurrently composite with multilayered graphite nanosheets. The obtained mesoporous CoCO₃ has a specific surface area of 143.7 m² g⁻¹, 12.4 times that of commercial CoCO₃. The preparation mechanism is studied in-depth, where urea, NH₄HCO₃, EG, and crystal water play essential and respective roles. The synergistic effect of the mesopore and graphite nanosheets facilitates long-term cycling stability (1465 mAh g⁻¹ after 450 cycles at 200 mA g⁻¹ with 101.1% capacity retention) and high-rate performance (1033 mAh g⁻¹ at 2.0 A g⁻¹). The essential roles of mesopores and graphite nanosheets in boosting the kinetic change are investigated.     

Electrochemical properties of Li<Subscript>3</Subscript>V<Subscript>2</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>/C cathode materials synthesized via ethylene glycol-assisted solvothermal method

The Li₃V₂(PO₄)₃/C (LVP/C) cathode materials for lithium-ion batteries were synthesized via ethylene glycol-assisted solvothermal method. The phase composition, phase transition temperature, morphology, and fined microstructure were studied using X-ray diffraction (XRD), differential thermal analyzer (DTA), scanning electron microscope (SEM), and transmission electron microscope (TEM), respectively. The electrochemical properties, impedance, and electrical conductivity of LVP/C cathode materials were tested by channel battery analyzer, the electrochemical workstation, and the Hall test system, respectively. The results shown that the appropriate amount of water added to ethylene glycol solvent contributes to the synthesis of pure phase LVP. The LVP₁₀/C cathode material can exhibit discharge capacities of 128, 126, 126, 123, 124, and 114 mAh g^?1 at 0.1, 0.5, 2, 5, 10, and 20 C in the voltage range of 3.0–4.3 V, respectively. Meanwhile, it shows also a stable cycling performance with the capacity retention of 89.6% after 180 cycles at 20 C.     

Ordered mesoporous silica materials (SBA-15) with good heat-resistant magnetism

A series of highly ordered mesoporous materials (CF-SBA-15) with heat-resistant magnetism have been successfully prepared from impregnation of cobalt salt, iron salt, and citric acid with as-synthesized SBA-15. XRD and N₂ isotherms indicate that these materials have highly ordered hexagonal mesoporous symmetry and open pore systems. The measurement of magnetic property shows that these materials are ferromagnetic even if calcined at 550 °C for 10 h in air, indicating their good heat-resistant magnetism. These results would be very important for recycle and regeneration of adsorbents and catalysts in practical applications. Moreover, this method may be useful for other mesoporous materials with thermally stable magnetism from a combination of other mesoporous materials such as MCM-41 with magnetic nanoparticles of MnFe₂O₄ and NiFe₂O₄.     

Synthesis and characterization of ionic liquid-functionalized alumino-silicate MCM-41 hybrid mesoporous materials

Ionic liquid-functionalized alumino-silicate MCM-41 hybrid mesoporous materials have been synthesized with two-step approach, by means of in situ skeleton doping with aluminium and post surface grafting with N-methylimidazole ionic liquid groups. The samples were characterized by X-ray diffraction (XRD), high resolution transmission electron microscope (HRTEM), N₂ adsorption-desorption, Fourier transform infrared (FTIR) spectra, ²⁷Al and ¹³C MAS NMR spectra and temperature-programmed desorption (TPD) of NH₃. The results indicated that the bifunctionalized MCM-41 possessed ordered mesostructure. Aluminium was efficiently introduced into the framework of the mesostructure, generating Lewis and Brönsted acid sites. N-methylimidazole ionic liquid groups were covalently grafted onto the surface of mesoporous materials. The as-synthesized bifunctional MCM-41 showed good catalytic performance in the coupling reaction of CO₂ and propylene oxide.     

Direct synthesis and characterization of phenyl-functionalized SBA-15

Phenyl-functionalized SBA-15 materials (Ph-SBA-15) were directly synthesized by using tri-block copolymer Pluronic P123 as templating agent under acidic conditions. The samples were characterized by Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetry analysis (TGA) and N₂ adsorption-desorption. The results show that the phenyl groups are covalently attached to the pore wall of SBA-15 after modification. The functionalized materials still preserve a desirable two-dimensional P6mm hexagonal structure and have large specific surface area and pore volume although the molar ratio of phenyltrimethoxysilane in total silica precursors is as high as 23.0%.     

Polyol-assisted synthesis of TiO2 nanoparticles in a semi-aqueous solvent

TiO₂ (anatase and rutile) nanoparticles with an average crystallite size of 20-40 nm have been prepared at room temperature by polyol-mediated synthesis technique in a semi-aqueous solvent medium using titanium iso-propoxide as the titanium source, acetone as the oil phase and ethylene glycol as the stabilizer. Phase and microstructure of the resultant materials have been characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. Photocatalytic degradation of acetaldehyde using TiO₂ nanoparticles was investigated by gas-chromatography technique.     

Lipid chain mobility in interdigitated DPPC systems

The segmental lipid chain mobility in the gel phase of dipalmitoylphosphatidylcholine (DPPC) multilayers dispersed in buffer and in the interdigitated gel phase induced by glycerol, ethylene glycol, ethanol and chaotropic salt NaClO₄ was compared by using conventional electron spin resonance (ESR) spectroscopy. The stearic acids bearing the nitroxide moiety at different positions down the acyl chain (n-NSA,n-5, 7, 10, 12 and 16) were used to characterized the chain motion, and the outer hyperfine splittings of the spectra, 2A _max, were taken as indices of the rotational mobility of the chain in the gel phase. The ESR measurements revealed a gradient of increased mobility on proceeding towards the terminal methyl end in the fully hydrated gel phase of DPPC bilayers. This gradient was reduced in the interdigitated gel phase induced by ethanol and chaotropic salt NaClO₄, whereas the rotational mobility throughout the length of the chain was comparable to that near the polar/apolar interface in the interdigitated gel phase in glycerol and ethylene glycol. Moreover, the motional anisotropy was much less affected by temperature in the interdigitated gel state of DPPC in glycerol and ethylene glycol as compared both to normal bilayer gel phase and to the other interdigitated DPPC systems. Finally, there was no evidence for chain interdigitation in the fluid phase of DPPC dispersions in any medium.     

有序介孔SBA-15复合稀土Tb络合物的制备和发光特性

以三嵌段化合物P123为模板剂、正硅酸乙酯(TEOS)为硅源,利用水热法制备出有序介孔二氧化硅SBA-15,随后利用3-氨丙基三乙氧基硅烷(APTES)、乙酰丙酮(ACAC)分步对该有序介孔材料进行改性,再将其置于乙醇溶液中,加入三价稀土Tb的盐溶液进行络合,制备出具有强发光性能的有序介孔纳米复合稀土材料。采用XRD、FTIR和荧光光谱等分析方法对复合材料的结构与性能进行了研究。发现有序介孔材料、第二配体(邻菲口罗啉Phen)对稀土络合物发光强度有重要影响,并对其机理进行了解释。另外,发现其热稳定性也有所提高。     

Tuning the morphology of mesoporous silica by using various template combinations

By using different dual-template combinations, four types of mesoporous silica materials with different morphologies were successfully synthesized. A solid-sphere mesoporous (SSM) silica was obtained using a combination of tri-block copolymer (F127) and 1,12-diaminododecane (DADD), but when F127 was substituted with poly(vinylpyrrolidone) (PVP), a leaf-shaped mesoporous (LSM) silica was obtained. In addition, a hollow-sphere mesoporous (HSM) silica was obtained by using a combination of PVP and dodecylamine (DDA), but a cotton-like mesoporous (CLM) silica was obtained using F127 instead of PVP. All four types of synthesized materials were characterized by SEM, TEM, XRD, and N₂ adsorption–desorption isotherms, and the results showed that all of them exhibited high surface area, large pore volume, worm-like pore structure, and beautiful shapes. The results of storage experiments revealed that the HSM and CLM showed good adsorption and storage properties. The HSM (the largest pore volume) seemed to have the larger storage capacity when compared to the CLM, albeit CLM had the highest surface area among all.     

Synthesis and characterization of Co (Ni or Cu)-MCM-41 mesoporous molecular sieves with different amount of metal obtained by using microwave irradiation method

Co (Ni or Cu)-MCM-41 mesoporous molecular sieves with different amount of metal were synthesized by using cetyltrimethyl ammonium bromide as a template and by a novel microwave irradiation method. These samples were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and N₂ physical adsorption. The experimental results show that Co (Ni or Cu)-MCM-41 mesoporous molecular sieves were successfully synthesized. When the as-synthesized samples were calcined at 550 °C for 10 h, the template was effectively removed. Under microwave irradiation condition, Co-MCM-41 mesoporous molecular sieves have specific surface areas in a range of 745.7-1188.8 m²/g and average pore sizes in a range of 2.46-2.75 nm; Ni-MCM-41 mesoporous molecular sieves have specific surface areas in a range of 625.8-1161.3 m²/g and average pore sizes of ca. 2.7 nm; Cu-MCM-41 mesoporous molecular sieves have specific surface areas in a range of 601.6-1142.9 m²/g and average pore sizes in a range of 2.46-2.76 nm. On the other hand, with increasing the introduced metal amount, the specific surface area and pore volume of the synthesized Co (Ni or Cu)-MCM-41 mesoporous molecular sieves became small, and the mesoporous ordering of the samples became poor. Under the comparable synthesis conditions, the synthesized Co-MCM-41 mesoporous molecular sieve has a bigger specific surface area and a more uniform pore distribution as compared with the synthesized Ni-MCM-41and Cu-MCM-41 mesoporous molecular sieves.     

Shape‐Tunable Selective Synthesis of Bismuth Fluoride Nanostructures for Versatile Applications

A facile approach for shape‐tunable synthesis of bismuth fluoride nanoparticles is reported. The approach is based on the homogeneous precipitation of precursor materials in mixed solvents (H₂O and ethylene glycol) and only ethylene glycol. The influencing factors on the morphology of the particles, i.e., solvent ratio, F/Bi ratio, and ethylenediaminetetraacetic acid, are studied in detail, and are schematically illustrated. The morphology, crystallinity, structure, and optical properties of the prepared samples are characterized by using a field‐emission scanning electron microscope, transmission electron microscope, X‐ray diffractometer, Fourier transform infrared spectrometer, and spectrofluorometer, respectively. The hollow sphere‐shaped nanoparticle doped with Eu³⁺ ions exhibit reddish orange emission under ultraviolet illumination due to the symmetric environment around the dopant ions. Subsequently, the effect of dopant concentration on the optical properties is also evaluated. The temperature‐dependent photoluminescence emission spectra reveal good thermal stability. The obtained results provide an efficient strategy for synthesizing the shape‐tunable nanoparticles with excellent optical properties.     

Functionalized SBA-15 materials for bilirubin adsorption

To investigate the driving force for bilirubin adsorption on mesoporous materials, a comparative study was carried out between pure siliceous SBA-15 and three functionalized SBA-15 mesoporous materials: CH₃-SBA-15 (MS), NH₂-SBA-15 (AS), and CH₃/NH₂-SBA-15 (AMS) that were synthesized by one-pot method. The obtained materials exhibited large surface areas (553-810 m²/g) and pore size (6.6-7.1 nm) demonstrated by XRD and N₂-ad/desorption analysis. The SEM images showed that the materials had similar fiberlike morphology. The functionalization extent was calculated according to ²⁹Si MAS NMR spectra and it was close to the designed value (10%). The synthesized mesoporous materials were used as bilirubin adsorbents and showed higher bilirubin adsorption capacities than the commercial active carbon. The adsorption capacities of amine functionalized samples AMS and AS were larger than those of pure siliceous SBA-15 and MS, indicating that electrostatic interaction was the dominant driving force for bilirubin adsorption on mesoporous materials. Increasing the ionic strength of bilirubin solution by adding NaCl would decrease the bilirubin adsorption capacity of mesoporous material, which further demonstrated that the electrostatic interaction was the dominant driving force for bilirubin adsorption. In addition, the hydrophobic interaction provided by methyl groups could promote the bilirubin adsorption.