Polypyrrole (PPY)/nitric acid (HNO3) activated carbon aerogel (HCA) composites are prepared through chemical oxidative polymerization with different PPY/HCA mass ratios. Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscope (SEM) were employed to investigate the components and morphology of the samples. The results demonstrate that the synthesized materials maintain the three-dimensional nanoporous structure of the carbon aerogel (CA); the activation by nitric acid and composition with PPY do not destroy the porous structure of the carbon aerogel and the complex still has the original three-dimensional nanoporous structure. Composites with different mass ratios (3 : 1, 2 : 1, 1 : 1, 1 : 2, 1 : 3) of PPY/ HCA were prepared and the electrochemical properties were measured by cyclic voltammetry, galvanostatic charge-discharge test, and electrochemical impedance spectroscopy. The results confirm that the PPY/HCA composite with a ratio of 1 : 1 exhibits the best electrochemical performances; it has a high specific capacitance of 336 F.g(-1), which is more than two times higher than that of CA (103 F.g(-1)); it also exhibits outstanding conductivity and cycling stability, retaining 91% of its initial capacitance after 2000 cycles. Therefore, this composite is quite a promising electrode material for supercapacitors.

We report a novel method to synthesize silica aerogel composite by fibers using low cost sodium silicate as precursors, ceramics fibers as reinforced skeleton (15wt %), via ambient pressure drying process. To minimize shrinkage during drying, surfaces of wet silica aerogel were modified using trimethylchlorosilane (TMCS) via one-step solvent exchange and surface modification. Composite SiO2 aerogels exhibited stable hydrophobic (contact angel about ~135° in room temperature), low density (0.196 g/cm3), high specific surface area (630 m2/g) and large pore volume (2.6cm3/g). Thermal conductivities at desired temperatures were analyzed by transient plane heat source method. Thermal conductivity coefficients of composite aerogel monoliths changed from 0.0266 to 0.0572 W/(m·K) as temperature increased to 400°C, revealed an excellent heat insulation effect during thermal process. Our work will be helpful to provide a general guide on how to commercial exploitation composite aerogel monoliths, which possessing 7.2cm diameters and have desirable structure and properties using in heat insulation environment.

A composite of silica hydrogel with ceramic fibers (15% in mass fraction) was synthesized with sodium silicate as a precursor and deionized water as a solvent by a sol?gel method, and the composite was subsequently modified with a solution of ethanol/trimethylchlorosilane/n-hexane via one-step solvent exchange and surface modification, thus obtaining the crack-free and high hydrophobic composite aerogel monoliths. The composite aerogel has a low density of 0.216 g/cm3 and a superior formability. The ceramic fibers can be dispensed into the sample and combined with the silica aerogel network. There is a spongy meshwork structure on the surface of the aerogel. The aerogel samples were characterized by microstructure, analysis, specific surface area measurement, thermogravimetric analysis, hydrophobicity, elastic modulus and thermal conductivities test, respectively. The results show that the specific surface area of the composite aerogel is 743 m2/g, the contact angle with water is 146°, and the elastic modulus is 5.1 MPa. After a thermal process in the temperature range from room temperature to 400 ℃, the hydrophobicity remains unchanged (about 138°), and the thermal conductivity of composite aerogel monoliths changes from 0.026 3 W/(m·K) to 0.051 2 W/(m·K). In addition, the mechanisms of solvent exchange and surface modification were also discussed.

Introduction There is a growing interest to minimize the emissions of nitrous oxide (N2O) as side-product from nitric acid plants due to a global warming potential of approximately 300 times higher than that of CO2. Different strategies have already been implemented at industrial scale but they are still suffering from significant drawbacks essentially associated to a poor selectivity and sometimes a short lifetime in particular when the catalytic process is inserted downstream the ammonia burner. Previous in-situ XRD measurements performed in our laboratory revealed the excellent thermal stability of perovskite based catalysts in the presence of steam at high temperature [1], which suggests its potential application for the decomposition of nitrous oxides from nitric acid plants. X-Ray Photoelectron Spectroscopy measurements usually evidence a surface atomic ratio of Co/La<1 that could reflect a surface enrichment in Lanthanum. The non-stoichiometric perovskite-based catalysts were examined in order to investigate a possible support effect of segregated oxides on perovskite that could enhance or lower the catalytic activity subsequently. An additional aspect has to be taken into account associated with the catalyst selectivity because the decomposition of NO must be avoided to preserve the cost efficiency of those typical industrial plants. Materials and Methods Stoichiometric and Lanthanum-deficient Perovskite-based catalysts (LaCo1-yO3±λ La1-xCoO3±λ, La1-xCo0.8Fe0.2O3±λ and La1-x-yCeyCo0.8Fe0.2O3±λ) were synthesized according to a conventional sol-gel method involving a citrate route [2]. Precursors thus obtained were dried overnight at 80°C then calcined in air at 600°C or 900 °C for 8 h. The prepared catalysts were characterized by BET, XRD, H2-TPR and XPS. Temperature-programmed experiments were performed in a fixed-bed flow reactor using 0.7 g of catalyst with a total flow of 15 L.h within a temperature range between 20 and 900°C. The reactant mixture was typically composed of 0.1 vol.% N2O, 5 vol.% NO, 6 vol. % O2, 15 vol. % H2O and balanced by He. A second catalytic test was performed after ageing overnight at 900°C under reactant mixture in order to characterize the thermal stability of our catalysts in the presence of steam. Results and Discussion The XRD patterns recorded on the catalysts evidence the rhombohedral structure of LaCoO3 and a slight segregation of La2O3 on LaCo1-yO3±λ samples that could be related with the increase of specific surface area up to 12 m/g (LaCo0.8O3 calcined at 900°C). In the case of La1-xCo0.8Fe0.2O3±λ samples, a progressive segregation of cobalt oxide is revealed with decreasing lanthanum stoichiometry but the specific surface area remains almost unaffected. The reducibility of these series of catalysts is examined by using H2-temperature-programmed reduction. The typical profile related to H2 consumption exhibits 2 domains of reduction, the reduction of Co into Co around 300-450°C and the subsequent reduction of Co into Co above 500°C in agreement with H2 consumption. The modification of stoichiometry slightly changes the reducibility accompanied with a shift of temperature Tmax for both domains. The characterisation of solids clearly evidences the formation of perovskite structure and the segregation of either La2O3 that enhances the specific surface area for LaCo1-yO3±λ or the preferential segregation of Co3O4 in the case of La1-xCo0.8Fe0.2O3±λ solids. We pay a special attention to a possible support effect that could involve the stabilisation of active phase.

The electrochemical performances of resorcinol–formaldehyde-based carbon aerogels can be significantly enhanced by nitric acid activation.FT-IR spectra and SEM images reveal the constitution and morphology of samples .The electrochemical performances of materials were tested by cyclic voltammetry,galvanostatic charge/discharge test ,electrochemical impedance spectroscopy and cyclic test. The results show that activation does not influence the molecular structure of carbon aerogels,which maintains their nano-porous structure. Activation increases the specific capacitance by 50% and improves the conductivity of carbon aerogels,resulting in fenfect cycling stability. So nitric acid activated carbon aerogels is an ideal electrode material for supercapacitors.

With HF as catalyst,nano-porous silica xerogels of high specific surface area(450~800 m~2·g~(-1)) was directly prepared at ambient pressure.Based on experiments,the influence of stuff proportion and heating temperature was investigated,and the adsorption capacities of the silica xerogels were studied by ultraviolet spectrophotometer.The results show that the silica xerogels with nano-porous structure have good adsorption properties and cycling performance,which are suitable for liquid absorption applications.

The fabrication procedures of dual-layer polystyrene(CH)/Al perturbation target were investigated.Perturbation patterns were introduced onto Al foil with thickness of 50 μm by laser micro-machining process,and the period and amplitude of the patterns were about 55 μm and 4.7 μm,respectively.CH film with thickness of 20 μm was directly coated on the surface of patterned Al foil by spin-coating process.The dual-layer CH/Al perturbation target was prepared by micro-cutting and micro-assembling process.The width and thickness of the target were about 200 μm and 70 μm,respectively.The target had been performed at "SG-Ⅱ" laser facility to investigate hydrodynamic instability in 2010.

In this work, the micro-structure and surface modification of sol-gel silica film were studied, for obtaining hydrophobic coatings with high transparency. Polyethylene glycol (PEG) was added into silica sol to adjust the particle size. Two kinds of surface modification (sol treatment and film treatment respectively) by hexamethyldisilazane (HMDS) were employed and compared. The particle size evolvement was measured by dynamic scattering particle size analyzer. The surface morphology, water contact angle, chemical compositions, and transmittance were characterized by atomic force microscope (AFM), contact angle instrument, transmittance, FTIR and UV-Vis-IR spectrophotometers. Results showed that addition of PEG increased the silica particle size and accordingly the film surface roughness, which gave rise to a significantly improved hydrophobicity. The surface modification was impacted by the particle size. Small particle size is good for sol treatment, while large particle size is good for film treatment. PEG-film after HMDS atmosphere treatment could present superhydrophobicity with water contact angle of 152 degrees, and high transmittance was maintained at the same time.

Prepared with sodium silicate precursor,ethanol(EtOH)/ hexamethyldisiloxane(HMDSO) /hydrochloric acid(HCL) as solvent exchange and surface modification agent,the crack-free and high hydrophobic silica aerogel monoliths were obtained.Silica aerogels possessed the superior properties,such as low density,high surface area,high hydrophobicity and low thermal conductivity.Silica aerogel monoliths maintained hydrophobic behavior up to a maximum temperature of 460℃ above which they become hydrophilic.After a thermal process changing from room temperature to 400 ℃,the final product still remained hydrophobic and presented good performance with the surface area of 530 m~2·g~(-1).Thermal conductivity coefficients of silica aerogelmonoliths changed from 0.025 to 0.049 W·(m·K)~(-1) as temperature increased from 25 ℃ to 400 ℃,an excellent heat insulation effect during thermal process remained.

Nano-porous silica aerogels doped with mullite fibers were prepared via sol-gel progress with polyethoxydisiloxanes (E-40) as silicon source. The mullite fibers were distributed inside the silica aerogels to act as a supporting skeleton material, which could increase the mechanical property. The morphology and pore structure of silica aerogels doped with fibers were characterized by SEM. The mechanical properties and the thermal conductivities of silica aerogel-fiber composites were determined by a dynamic mechanical analyzer and a hot disk device. The silica aerogels doped with fibers still maintain a spongy porous structure and high porosity, even after the heat treatment. The mechanical strength of the silica aerogels increases from 1.5x10(5) to 3.8x10(6) Pa. With the rising of the heat treatment temperature, the mechanical strength of the composites would be increased to 10-20 times. The thermal conductivity of silica aerogels is 0.023 W/(m.K) at room temperature in air. The thermal conductivity of the composites is 0.032 W/(m.K) after 1000 degrees C and is still recognized as the preferred super-insulation material.

Continuous formation technics were used for the fabrication of gradient density silica aerogel monoliths. The shape of gradient density silica aerogel monoliths shrink linearly. Its density ranged approximately from 0.010 similar to 150 g/cm(3). With the density varying from low to high, the transparency of the sample increased and gray scale decreased, which presented a gradient distribution. The gradient density aerogel monoliths also had a high surface area (859 m(2)/g) and high pore volume (5.7 cm(3)/g) in low density areas; in contrast, the high density areas of silica monoliths had a low specific surface area 565 m(2)/g and low pore volume (2.8 cm(3)/g). This continuous formation technics may potentially be expanded to the fabrication of other gradient density materials.

Silver colloid nanoparticles, with high Ag+ concentration (up to 0.025 mol/L) and high stability (up to 5 months), have been synthesized via one step reduction of AgNO3 by glucose in the presence of cationic surfactant cetyltrimethylammonium bromide (CTAB). The reaction process, size distribution, morphology, and structure of particles have been characterized by UV/Visible absorption spectrophotometry, transmission electron microscopy (TEM) and X-ray diffractometer (XRD). Results indicate that CTAB accelerates the reaction between silver ions and glucose, because it stabilizes H+. TEM images show that silver sol consists of well-dispersed agglomerates of spherical nanoparticles with particle size from 10 to 40 nm.

The method about fabrication and characterization of graded density aerogel flyer target for extending loading time in laser-driven equation of state(EOS) experiment was introduced.The preparation of the target involved the synthesis of organic resorcinol-formaldehyde(RF) aerogel.RF hydrosol was prepared via sol-gel process with resorcinol-formaldehyde-water system and catalyzed by sodium carbonate.Also,an airtight micro-mold was used in layer-by-layer gelation process.After gelation,the RF wet gel was demoulded in ethanol condition and substituted with ethanol one time per day for three days to remove the residual solution.The treated RF wet gel was converted to RF aerogel via vacuum drying after the residual solution was completely removed.The Fourier transform infrared spectroscopy,field emission scanning electron microscopy(FESEM),X-ray phase contrast imaging instrument and surface area and porosity analyzer were used to characterize the composition,morphology,density,interlayer coupling and microstructure of the flyer target.A four-layer target with total thickness of about 120 μm and density of about 400-1 200 mg/cm3 was obtained and characterized in the experiment.

The hydrophobic and mesoporous SiO2 aerogels were prepared with low cost sodium silicate as precursors via an ambient pressure drying process including solvent exchange of ethanol and surface modification of a hexamethyl-disiloxane-hydrochloric acid mixture.The SiO2 aerogels with the low density（80-200 mg/cm3）,the high specific surface area（568 m2/g） and the large pore volume（2.9 cm3/g） exhibited hydrophobic（the contact angle from 155°to 130°in 0-400 ℃）.The thermal conductivity of the aerogels at room temperature was only 0.026 W/（m？K）.

Nano-porous monolithic SiO2 aerogel as insulation material was prepared from silicon alkoxide as the precursor materials, followed by ethanol supercritical drying in this paper. In order to improve the mechanical properties of silica aerogel monoliths, the ceramic fibers were mixed in the pure aerogel, or integrating inorganic fiber materials as skeleton materials with low thermal conductivity supporting. Instron 5566, 5500R Material Testing Machine was used to measure the mechanical intensity. SEM was used to characterize the morphology of the silica aerogel monoliths. The thermal properties of the silica aerogels were determined by using the Hot Disk device. The results show that new type composite materials had a low effect on the thermal conductivities of the silica aerogel monoliths, but improved the mechanical intensity clearly. It made a great progress in the practical application of the SiO2 aerogel monoliths.

The SiO2/carbonized resorcinol formaldehyde (CRF) bilayer perturbation aerogel target was designed and fabricated to investigate the growth of Rayleigh–Taylor instability (RTI) at "SG-II" laser facility. The target was composed of SiO2 and CRF aerogel sheet, whose density and microstructure were controllable. To begin with, freestanding CRF aerogel sheet was prepared by sol–gel and carbonization process. Then, as the seed of the growth of RTI, sine-like perturbation patterns were introduced onto the surface of CRF aerogel sheet by picosecond laser micro-machining process. Finally, SiO2 aerogel sheet was directly formed on the patterned surface of CRF aerogel sheet by sol–gel process not only to avoid the use of adhesive but also to eliminate the gaps between the two aerogel sheets. The parameters of the target, such as perturbation period (T), perturbation amplitude (A), the thickness of CRF aerogel sheet (H1) and the thickness of SiO2 aerogel sheet (H2), were measured. The pore size distribution, density homogeneity and laser machining process were discussed. The interface between CRF aerogel sheet and SiO2 aerogel sheet was characterized.

The adsorption properties of hydrophobic silica aerogels were studied. Polyethoxy- disiloxanes (E-40), ethanol (EtOH), hydrogen fluoride (HF) were used as silican precursor, solvent and catalyst, respectively, followed by solvent substitution and surface modification to prepare silica aerogels. Scanning electronic microscopy, nitrogen adsorption analyzer, contact angle measurement and Fourier transform infrared spectroscopy were used to characterize the structure and properties of silica aerogels. The conclusion is that the silica aerogels are with good hydrophobicity and the gas adsorption capacities is excellent for toxic gases such as benzene and carbon tetrachloride, which is 2~3 times higher than that of activated carbon fiber (ACF) or granule of activated carbon (GAC). Moreover, the adsorption capacity for organic solvent is 20-30 times of its own weight, which is much larger than that of GAC or Poly vinyl alcohol (PVA). In addition, the adsorption capacity of silica aerogels remains almost the same value after two times of adsorption- desorption processes, which means that the process is recyclable, low-cost and environmental friendly.

The effect of different surface modification agents on the hydrophobic, mechanical and thermal properties of ambient pressure dried silica aerogels was studied. Aerogels were synthesized by sol-gel method using Tetramethoxysilane (TMOS), ethanol (EtOH) and hydrogen fluoride (HF) as precursor, solvent and catalyst, respectively. The optimal volume ratio of TMOS: EtOH: HF is 1: 3:0.05. Methyltrimethoxysilane (MTMS), hexamethyldisilazane (HMDZ) and trimethylchlorosilane (TMCS) were selected as surface modification agents, The characteristics of aerogels with different modifications were analyzed by Scan electron microscope, Contact angle meter, Fourier transform infrared spectroscopic, dynamic mechanical analyzer and hot disk thermal analyzer. The results show that aerogels modified with TMCS has the largest contact angle (149 degrees) followed by HMDZ agents, and the contact angle of aerogels modified with MTMS is the smallest (136 degrees). The mechanical and thermal properties of the three modified aerogels are good and show little differences. The elastic modulus of aerogels is about 3.85 MPa at room temperature and the thermal conductivity is as low as 0.029 W/(m.K).

Catalytic activity for the N2O decomposition into N2 was investigated on perovskite-based materials in the presence of 5vol% NO, 6vol% O2 and 15vol% H2O. This feed is typical of industrial conditions for nitric acid plants operating at high temperature (850–900°C). The catalytic properties were found to be sensitive to the surface composition as revealed by XRD and XPS. Surface reconstructions on La and Co deficient perovskites induced surface La or Co enrichment. The latter governed the catalytic properties at medium and high temperature and was related to change in oxygen mobility. The presence of water was found as an outstanding parameter to speed up structural changes at the surface. However the presence of water had globally a negative impact in the catalytic activity in N2O decomposition. Surface changes which determined the extent of deactivation were more accentuated on Co-deficient perovskites due to La2O3 segregation. Higher resistance to deactivation was obtained on La-deficient perovskites such as La0.8CoO3 and La0.9Co0.8Fe0.2O3. Surface reconstruction was evidenced at high temperature in severe reaction conditions.

The experimental results of thermal process on the microstructural and physical properties of ambient pressure dried hydrophobic silica aerogel monoliths are reported and discussed. With sodium silicate as precursor, ethanol/hexamethyldisiloxane/hydrochloric acid as surface modification agent, the crack-free and high hydrophobic silica aerogel monoliths was obtained possessing the properties as low density (0.096 g/cm3), high surface area (651 m2/g), high hydrophobicity (~147°) and low thermal conductivity (0.0217 Wm/K). Silica aerogels maintained hydrophobic behavior up to 430 °C. After a thermal process changing from room temperature to 300 °C, the hydrophobicity remained unchanged (~128°), of which the porosity was 95.69% and specific density about 0.094 g/cm3. After high temperature treatment (300–500 °C), the density of final product decreased from 0.094 to 0.089 g/cm3 and porosity increased to 96.33%. With surface area of 466 m2/g, porosity of 91.21% and density about 0.113 g/cm3, silica aerogels were at a good state at 800 °C. Thermal conductivities at desired temperatures were analyzed by the transient plane heat source method. Thermal conductivity coefficients of silica aerogel monoliths changed from 0.0217 to 0.0981 Wm/K as temperature increased to 800 °C, revealed an excellent heat insulation effect during thermal process.