Preparation of Multi Cage-Like Zinc Oxide Nanopowder with High Specific Surface Area via a Large-Scale Hydrothermal Method

2012 ◽  
Vol 476-478 ◽  
pp. 714-720
Author(s):  
Bing Liu ◽  
Li Li ◽  
Li Qu
Keyword(s):  
Hydrothermal Method ◽  
Surface Area ◽  
Large Scale ◽  
Scale Up ◽  
High Specific Surface Area ◽  
Environmentally Benign ◽  
Molar Ratio ◽  
Zinc Oxides ◽  
Good Potential ◽  
Synthesized Materials

Multi cage-like zinc oxides were prepared via a facile hydrothermal method. The as-synthesized materials were characterized by means of XRD, TG-DTA, SEM, EDS, and N2 adsorption. The results indicate that the molar ratio of glucose to zinc cation has a significant effect on the morphology, surface area, pore size and distribution of the obtained products. This method is attractive for its merits such as simplicity, commercial feasibility, environmentally benign, surfactant-free, and good potential for scale-up.

The Influence of Fe/Al Molar Ratio on Microreactor-Based Catalyst Preparation and Carbon Nanotube Preparation

2021 ◽  
Vol 1036 ◽  
pp. 130-136
Author(s):  
Ting Qun Tan ◽  
Lei Geng ◽  
Yan Lin ◽  
Yan He
Keyword(s):  
Carbon Nanotubes ◽  
Catalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Small Diameter ◽  
High Specific Surface Area ◽  
Detection Methods ◽  
Molar Ratio ◽  
High Catalytic Activity

In order to prepare carbon nanotubes with high specific surface area, small diameter, low resistivity, high purity and high catalytic activity, the Fe-Mo/Al2O3 catalyst was prepared based on the microreactor. The influence of different Fe/Al molar ratios on the catalyst and the carbon nanotubes prepared was studied through BET, SEM, TEM and other detection methods. Studies have shown that the pore structure of the catalyst is dominated by slit pores at a lower Fe/Al molar ratio. The catalytic activity is the highest when the Fe/Al molar ratio is 1:1, reaching 74.1%. When the Fe/Al molar ratio is 1:2, the catalyst has a higher specific surface area, the maximum pore size is 8.63 nm, and the four-probe resistivity and ash content of the corresponding carbon nanotubes are the lowest. The higher the proportion of aluminum, the higher the specific surface area of the catalyst and the carbon nanotubes, and the finer the diameter of the carbon nanotubes, which gradually tends to relax. The results show that when the Fe/Al molar ratio is 1:2, although the catalytic activity of the catalyst is not the highest, the carbon nanotubes prepared have the best performance.

scholarly journals Synthesis and characterization of porous silica and polyaniline-porous silica composite materials with high surface area

2014 ◽  
Vol 49 (1) ◽  
pp. 1-8
Author(s):  
US Akhtar ◽  
MK Hossain ◽  
MS Miran ◽  
MYA Mollah
Keyword(s):  
Electron Microscopy ◽  
Pore Size ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Porous Silica ◽  
Nitrogen Adsorption ◽  
High Specific Surface Area ◽  
Molar Ratio ◽  
Cylindrical Pore

Porous silica materials were synthesized from tetraethyl orthosilicate (TEOS) using Pluronic P123 (non-ionic triblock copolymer, EO20PO70O20) as template under acidic conditions which was then used to prepare polyaniline (PAni) and porous silica composites (PAnisilica) at a fixed molar ratio. These materials were characterized by nitrogen adsorption-desorption isotherm measured by Barrett-Joyner- Halenda (BJH) method and pore size distribution from desorption branch and surface area measured by the Brunauer-Emmett-Teller (BET) method, scanning electron microscopy (SEM), transmission electron microscopy (TEM), TEM-energy dispersive X-ray (EDX) and Fourier transform infrared (FT-IR) spectroscopy. The composite maintains its structure even after the polymerization and the polymer is dispersed on the inorganic matrix. The rod-like porous silica was about 1?m to 1.5 ?m long and on an average the diameter was in the range of 300- 500 nm. The SEM and TEM images show well ordered 2d hexagonal pore, high specific surface area (850 m2g-1) and uniform pore size of ca. 6.5 nm in diameter. After incorporation of PAni inside the silica pore, framework of porous silica did not collapse and the surface area of the composite was as high as 434 m2g-1 which was 5.5 time higher than our previous report of 78.3 m2g-1. Due to shrinkage of the framework during the incorporation of aniline inside the silica, the pore diameter slightly increase to 7.5 nm but still showing Type IV isotherm and typical hysteresis loop H1 implying a uniform cylindrical pore geometry. DOI: http://dx.doi.org/10.3329/bjsir.v49i1.18847 Bangladesh J. Sci. Ind. Res. 49(1), 1-8, 2014

Preparation and Characterization of Ultralow Density Silica Aerogels by Acetonitrile Supercritical Drying

2012 ◽  
Vol 519 ◽  
pp. 83-86 ◽  
Author(s):  
Guang Wu Liu ◽  
Xing Yuan Ni ◽  
Bin Zhou ◽  
Qiu Jie Yu
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Silica Aerogel ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Silica Aerogels ◽  
High Specific Surface Area ◽  
Molar Ratio ◽  
Sol Gel Process

This paper deals with the synthesis of ultralow density silica aerogels using tetramethyl orthosilicate (TMOS) as the precursor via sol-gel process followed by supercritical drying using acetonitrile solvent extraction. Ultralow density silica aerogels with 6 mg/cc of density was made for the molar ratio by this method. The microstructure and morphology of the ultralow density silica aerogels was characterized by the specific surface area, SBET, SEM, and the pore size distribution techniques. The results show that the ultralow density silica aerogel has the high specific surface area of 812m2/g. Thermal conductivities at desired temperatures were analyzed by the transient plane heat source method. Thermal conductivity coefficients of silica aerogel monoliths changed from 0.024 to 0.043W/ (m K) as temperature increased to 400°C, revealed an excellent heat insulation effect during thermal process.

Preparation of Tin Oxide Nanometer Thin Films by Hydrothermal Method

2018 ◽  
Vol 279 ◽  
pp. 197-201
Author(s):  
Fang Wang ◽  
Yang Chao ◽  
Ming Han Xu ◽  
Rui Hua Wang ◽  
Ai Xia Chen ◽  
...  
Keyword(s):  
Solar Cell ◽  
Hydrothermal Method ◽  
Surface Area ◽  
Tin Oxide ◽  
Salt Concentration ◽  
Driving Force ◽  
Performance Test ◽  
Process Condition ◽  
Molar Ratio ◽  
Cell Conversion

Given the shortage of energy reserves, new energy sources must be identified. In this regard, improving the efficiency of solar cell conversion and simplifying the solar cell technology have become the focus of research. In this study, tin oxide nanometer thin film was fabricated on FTO conductive glass as photocathode through hydrothermal method. The synthesis condition was regulated, and performance test was also conducted. Results show that the crystallization driving force, crystallization rate, and grain size of tin dioxide crystal increase with increasing alkali ratio, leading to disorganized accumulation of tin oxide. Under prolonged holding time, tin oxide crystal became complete, and the surface area of the crystal increased. The crystallization driving force and rate also increased with increasing salt concentration and accompanied by clutter of tin oxide. The optimized process condition included 1:4 molar ratio of salt to alkali, 0.05 mol/L salt concentration, 200 °C reaction temperature, and 8 days of reaction. The highest specific surface area of the tin oxide nanometer film was obtained under the optimized condition.

Synthesis and Structural Characterization of SiO2-Al2O3 Xerogels

2007 ◽  
Vol 336-338 ◽  
pp. 2286-2289
Author(s):  
Fei He ◽  
Xiao Dong He ◽  
Yao Li
Keyword(s):  
Structural Change ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Mesoporous Structure ◽  
Supercritical Drying ◽  
High Specific Surface Area ◽  
Molar Ratio

Low-density xSiO2-(1-x)Al2O3 xerogels with x=0.9, 0.8, 0.7, 0.6 (mole fractions) were prepared by sol-gel and non-supercritical drying. Silica alkogels, which were the framework of binary composite materials, formed from tetraethyl orthosilicate (TEOS) by hydrolytic condensation with a molar ratio of TEOS: H2O: alcohol: hydrochloric acid: ammonia =1: 4: 10: 7.5×10-4: 0.0375. Aluminum hydroxide derived from Al(NO3)3·9H2O and NH4OH acting in the alcohol solution under the condition of catalyst. After filtrating and washing, the precipitation was mixed into silica sols to form SiO2-Al2O3 mixed oxide gels with different silicon and aluminum molar ratio. The structural change and crystallization of the binary xerogels were investigated after heat treatment at 600 for 2 h by the means of X-ray diffraction. Nitrogen adsorption experiment was performed to estimate specific surface area, porous volume and pore size distribution. The structural change of xerogels was observed by FT-IR spectroscopy. The resulting mixed xerogels possess of mesoporous structure which is characteristic of cylindrical pores, high specific surface area of 596-863 m2/g and a relatively narrow pore distribution of 2.8-30 nm. Al2O3 is introduced into the SiO2 phase and some of Al-O-Si bonds form.

Effect of Morphology of ZnCo2O4 Nanostructures on Electrochemical Performance

NANO ◽  
2016 ◽  
Vol 11 (08) ◽  
pp. 1650089 ◽  
Author(s):  
J. Y. Dong ◽  
N. Zhang ◽  
S. Y. Lin ◽  
T. T. Chen ◽  
M. Y. Zhang ◽  
...  
Keyword(s):  
Electrochemical Performance ◽  
Specific Surface ◽  
Electrochemical Properties ◽  
Specific Capacitance ◽  
Hydrothermal Method ◽  
Surface Area ◽  
Specific Surface Area ◽  
Nickel Foam ◽  
High Specific Surface Area ◽  
Active Materials

The ZnCo2O4 nanorods and nanosheets were grown on nickel foam by a facile and effective hydrothermal method, respectively. The effect of the morphologies of the nanostructures on electrochemical performance was investigated. Importantly, ZnCo2O4 nanorod electrodes with a high specific surface area exhibited a higher specific capacitance of 2457.4 F g[Formula: see text] at 2 A g[Formula: see text] and remarkable cycling stability with capacitance retention of 97.7% after 1000 cycles, which are superior to those of ZnCo2O4 nanosheet electrodes. Such a result is well explained. The investigation on the electrochemical properties of these two nanostructures as electrodes confirmed that the morphology of active materials has an important impact on electrochemical properties.

One-Pot Synthesis of LiFePO4 Nano-Particles Dispersed in N-Containing Melamine-Formaldehyde Carbon Matrix as the Cathode Materials for Large Scale Lithium Ion Batteries

2018 ◽  
Vol 775 ◽  
pp. 342-349
Author(s):  
Supacharee Roddecha ◽  
Kantawich Jittmonkong ◽  
Malinee Sriariyana
Keyword(s):  
Ionic Conductivity ◽  
Surface Area ◽  
Large Scale ◽  
Carbon Matrix ◽  
Nano Particles ◽  
Pluronic F127 ◽  
Molar Ratio ◽  
Melamine Formaldehyde ◽  
One Pot ◽  
One Pot Synthesis

LiFePO4 is considered as the promising cathode material for a large-scale Li batteries used in electrical vehicles (EVs). However, a practical use of LiFePO4 cathode is limited by its low ionic conductivity, resulting in low battery’s power performance. This work, a facile and practical method to promote ionic conductivity and capacity of LiFePO4 was developed by dispersing LiFePO4 nanoparticles into a porous nitrogen-riched carbon matrix by employing one-pot synthesis approach. The N-containing carbon porous matrix was prepared by utilizing melamine-formaldehyde (MF) resin as the N-containing carbon precursor and Pluronic F127 as the porous template. The pseudo capacitive effect attributed from lone-pair electrons into melamine functional group was expected to support Li ion transport. After carbonization at 600 °C, uniform LiFePO4 nanocomposite clusters with an average size of about 50-300 nm were obtained. The influence of the molar ratio between pluronic F127 and melamine-formaldehyde (i.e. F127:MF molar ratio as 0:1, 0.03:1, 0.3:1) on the LiFePO4 nanocomposite’s morphology and crystalline structure was investigated by using scanning electron microscope and X-ray diffraction technique. The results show that increasing F127 concentrations support more porous structure formation, leading to a higher surface area but does not affect the LiFePO4 nanocrystalline structure. According to the highest surface area, the N-doped carbon coated LiFePO4 composite product obtained from the molar ratio of F127:MF as 0.3:1 exhibited highest discharging specific capacity of 158.1 mAh g-1, at a rate of 0.1 C and also shows high cycle stability.

scholarly journals Development of Alumina–Mesoporous Organosilica Hybrid Materials for Carbon Dioxide Adsorption at 25 °C

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2301 ◽  
Author(s):  
Chamila Gunathilake ◽  
Rohan Dassanayake ◽  
Chandrakantha Kalpage ◽  
Mietek Jaroniec
Keyword(s):  
Surface Area ◽  
Hybrid Materials ◽  
Triblock Copolymer ◽  
Large Scale ◽  
High Specific Surface Area ◽  
Carbon Dioxide Adsorption ◽  
High Co2 ◽  
Mesoporous Organosilica ◽  
Bridging Groups ◽  
Enhanced Surface

Two series of alumina (Al2O3)–mesoporous organosilica (Al–MO) hybrid materials were synthesized using the co-condensation method in the presence of Pluronic 123 triblock copolymer. The first series of Al–MO samples was prepared using aluminum nitrate nanahydrate (Al–NN) and aluminum isopropoxide (Al–IP) as alumina precursors, and organosilanes with three different bridging groups, namely tris[3-(trimethoxysilyl)propyl]isocyanurate, 1,4-bis(triethoxysilyl)benzene, and bis(triethoxysilyl)ethane. The second series was obtained using the aforementioned precursors in the presence of an amine-containing 3-aminopropyltriethoxysilane to introduce, also, hanging groups. The Al–IP-derived mesostructures in the first series showed the well-developed porosity and high specific surface area, as compared to the corresponding mesostructures prepared in the second series with 3-aminopropyltriethoxysilane. The materials obtained from Al–NN alumina precursor possessed enlarged mesopores in the range of 3–17 nm, whereas the materials synthesized from Al–IP alumina precursor displayed relatively low pore widths in the range of 5–7 nm. The Al–IP-derived materials showed high CO2 uptakes, due to the enhanced surface area and microporosity in comparison to those observed for the samples of the second series with AP hanging groups. The Al–NN- and Al–IP-derived samples exhibited the CO2 uptakes in the range of 0.73–1.72 and 1.66–2.64 mmol/g at 1 atm pressure whereas, at the same pressure, the Al–NN and Al–IP-derived samples with 3-aminopropyl hanging groups showed the CO2 uptakes in the range of 0.72–1.51 and 1.70–2.33 mmol/g, respectively. These data illustrate that Al–MO hybrid materials are potential adsorbents for large-scale CO2 capture at 25 °C.

scholarly journals Synthesis of θ-Al2O3 Whiskers with Twins

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 895
Author(s):  
Nan Liao ◽  
Xiaojia Su ◽  
Haiwen Zhang ◽  
Qingguo Feng ◽  
Salvatore Grasso ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Specific Surface ◽  
Hydrothermal Method ◽  
Surface Area ◽  
Tetragonal Phase ◽  
Monoclinic Phase ◽  
Argon Atmosphere ◽  
Molar Ratio ◽  
Average Width ◽  
The Mean

In this work, θ-Al2O3 whiskers with twins were successfully fabricated by a hydrothermal method followed by annealing at 1000 °C in argon atmosphere using Al2(SO4)3·18H2O, CO(NH2)2 and PEG2000 as initial materials. It is confirmed that precursor of AlO(OH) whiskers is suitable to be used for preparing alumina whiskers when the molar ratio of Al3+: CO(NH2)2 is selected to be 1:6. The mean length of obtained whiskers is 1.5 μm and the average width is 0.1 μm. Interestingly, it is found that the as-prepared θ-Al2O3 whiskers consist of twins with (100) plane as the twin surface, which is ascribed to the phase transformation from tetragonal phase (δ-Al2O3) to monoclinic phase (θ-Al2O3) during the annealing. Additionally, the specific surface area of θ-Al2O3 whiskers is measured to be 38.2 m2/g.

scholarly journals Production of Al-Sc Alloy by Electrolysis from Cryolite Melt Using Secondary Feedstock Material

2021 ◽  
Vol 5 (1) ◽  
pp. 41
Author(s):  
Ana Maria Martinez ◽  
Samuel Senanu ◽  
Henrik Gudbrandsen ◽  
Karen Sende Osen ◽  
Anne Støre ◽  
...  
Keyword(s):  
Large Scale ◽  
Continuous Operation ◽  
Environmentally Benign ◽  
Molar Ratio ◽  
Galvanostatic Mode ◽  
Master Alloys ◽  
Electrolysis Cells ◽  
On Line ◽  
Feedstock Material

Electrolysis experiments to produce Al-Sc alloys were carried out in galvanostatic mode using a cryolitic melt with a NaF/AlF3 molar ratio of 2.2 at 980 °C, using both synthetic and waste feeds. After elucidation of the cryolite electrolyte bath chemistry when adding Sc2O3, small-laboratory scale trials allowed for the demonstration of the process and the study and for the optimisation of the electrolysis parameters. Experiments in large-scale electrolysis cells allowed us to run long-term trials in continuous operation, while the on-line monitoring of the cell off-gases ensured the environmentally benign performance of the process. The aluminium product obtained contained 0.6–2.6 wt% Sc, depending on the current density applied. The material is suited to prepare Al-Sc master alloys for 3D printing powders.

Sign in / Sign up

Export Citation Format

Share Document