Properties Of Mesoporous Materials Research Articles

Mesoporous Materials for Electrochemical Energy Storage and Conversion

AbstractDeveloping high‐performance electrode materials is an urgent requirement for next‐generation energy conversion and storage systems. Due to the exceptional features, mesoporous materials have shown great potential to achieve high‐performance electrodes with high energy/power density, long lifetime, increased interfacial reaction activity, and enhanced kinetics. In this Essay, applications of mesoporous materials are reviewed in electrochemical energy conversion and storage devices. The synthesis, structure, and properties of mesoporous materials and their performance in rechargeable batteries, supercapacitors, fuel cells, and electrolyzers are discussed, providing practical details and enlightening comments on the construction of high‐performance mesoporous electrodes. Lastly, the research challenges and perspectives on mesoporous materials for the future development of energy conversion and storage devices are assessed.

Influence of System Composition on Mesoporous Silica Materials using Lamellar Liquid Crystals as Templates

A novel and effective method for synthesis of mesoporous silica is reported in this paper. The method was based on the use of the tetraethoxysilane (TEOS) as precursor and the layered liquid crystals (LCs) as templates formed by cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). The range of the LCs was determined by exploring the phase behavior of the system with different ratios and concentrations of CTAB and SDS. The effects of the ratio of CTAB/SDS and the ratio of H2O and TEOS (defined as R) on the properties of mesoporous materials were studied. The results indicated that the specific surface area of mesoporous silica increased initially and then decreased with the increase of both R value and CTAB in the positive region. SEM photos showed that the synthesized mesoporous silica had a distinct lamellar structure.

Confinement effect on ultrafast events of a salicylideneaniline derivative within mesoporous materials

We report on femtosecond (fs) studies of HBA-4NP interacting with MCM41, Al-MCM41 and SBA15 materials, and discuss the dynamics of caged monomers and J-aggregates. For MCM41 and Al-MCM41 composites, and upon excitation at 380 nm (monomers region) the ultrafast dynamics (250 fs and 2.5 ps for HBA-4NP/MCM41, 350 fs and 3.5 ps for HBA-4NP/Al-MCM41) is slower than that observed in solution due to aggregates formation inside the material pores. While exciting at 410 nm, we got a slower behaviour. However, for HBA-4NP/SBA15 composites, with a low loading, where the caged monomers are the main guests, we recorded faster dynamics (200 fs and 2 ps) independently on the pumping wavelength. These results show how the properties of mesoporous materials, especially its pore size and Al-doping, affect the nature of the formed composites and their ultrafast photodynamics.

Drug delivery system for an anticancer agent, chlorogenate-Zn/Al-layered double hydroxide nanohybrid synthesised using direct co-precipitation and ion exchange methods

A nano-structured drug-inorganic clay hybrid involving an active anticancer compound, which is chlorogenic acid (CA) intercalated into Zn/Al-layered double hydroxide, has been assembled via ion-exchange and co-precipitation methods to form a nanohybrid CZAE (a chlorogenic acid-Zn/Al nanohybrid synthesised using an ion-exchange method) and CZAC (a chlorogenic acid-Zn/Al nanohybrid synthesised using a direct method), respectively. The X-ray diffraction (XRD) results confirmed that the CA-LDH had a hybrid structure in which the anionic chlorogenate is arranged between the interlayers as a horizontal monolayer at 90 and 20° angles from the x axis for CZAE and CZAC, respectively. Both nanohybrids have the properties of mesoporous materials. The high loading percentage of chlorogenic acid (approximately 43.2% for CZAE and 45.3% for CZAC) with basal spacings of 11.7 and 12.6Å for CZAE and CZAC, respectively, corroborates the successful intercalation of chlorogenic acid into the interlayer gallery of layered double hydroxides. Free chlorogenic acid and the synthesised nanocomposites (CZAE, CZAC) were assessed for their cytotoxicity against various cancer cells. The Fourier transform infrared data supported the formation of both nanohybrids, and a thermal analysis showed that the nanohybrids are more thermally stable than their counterparts. The chlorogenate shows a sustained release, and the release rate of chlorogenate from CZAE and CZAC nanohybrids at pH 7.4 is remarkably lower than that at pH 4.8 due to their different release mechanisms. The release rate of chlorogenate from both nanohybrids can be described as pseudo-second order. The present investigation revealed the potential of the nanohybrids to enhance the in vitro anti-tumour effect of chlorogenic acid in liver and lung cancer cells in vitro.

The Modification of Mesoporous Silica SBA-15-Type with PEG

In this study, first we prepared SBA-15 and sulfonate bearing SBA-15-SO3H.Then we modified the mesoporous silica with PEG to get SBA-15,SBA-15-SH,SBA-15-SO3H,SBA-15-PEG and SBA-15-SH-PEG.The samples were tested by FT-IR, nitrogen adsorption–desorption and TG. The tests showed that both SBA-15and SBA-15-SO3H we prepared had the typical properties of mesoporous materials. SBA-15-PEG and SBA-15-SH-PEG were successfully prepared.

Tissue regeneration: A new property of mesoporous materials

A new application of mesoporous materials as bone regenerators is described. In vitro bioactivity studies by soaking three different mesoporous materials, SBA-15, MCM-48 and MCM-41, in simulated body fluid (SBF) have been carried out. After the in vitro test, the study by Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, electron diffraction and microscopy shows that an apatite-like layer is formed on the surface of SBA-15 and MCM-48 materials after 30 and 60 days, respectively, allowing their use in biomedical engineering for tissue regeneration.

Surfactant effects on the physical properties of mesoporous silica and silicates

Mesostructured silicas and silicates have been synthesized using hydrogels with molar composition: M:26.0SiO 2:5.2(C 2H 5) 4NOH:7.5[CH 3(CH 2) 15N(CH 3) 3] 2O:790H 2O, where M=0, Zr(OC 3H 7) 4 or Ti(OC 4H 9) 4. In all preparations, colloidal silica (Ludox) was used as the source of silica. The hydrothermal transformation at 110°C of these gels produced solids with the hexagonal structure typical of MCM-41 type materials. The effects of chain length and surfactant terminal alkyl groups on the properties of mesoporous materials containing Ti or Zr, have been investigated by using different surfactants such as cetyl trimethyl ammonium bromide and chloride, cetyl dimethyl ethyl ammonium bromide, and myristyl trimethyl ammonium bromide. When the surfactant's carbonyl chain decreased to 14 from 16 carbon atoms, a reduction in unit cell dimension and average pore diameter was observed in the mesoporous silicas, titaniumsilicates and zirconiumsilicates under study. Replacement of methyl groups with ethyl groups on the surfactant hydrophobic head, had no measurable effects on crystals' properties. However, a surfactant with a bulky aromatic head group, such as cetyl pyridinium chloride, inhibited crystallization. In general, the use of bromide in place of chloride salts yielded more ordered MCM-41 type crystals. The high thermal stability (to 800°C), surface area (1000–1500 m 2/g), pore volume (0.90–1.20 cm 3/g) and uniform mesoporosity (with pore diameter in the 2.9 nm–3.6 nm range), of these metalsilicates could be of particular interest in the preparation of catalysts requiring siliceous metal supports.