Papers by Keyword: High Surface Area

Abstract: In this paper, a tunable TiO₂ nanorod cross-link structure with ultra-high surface area (up to 109.81 m²/g) has been successfully prepared via hydrothermally treating elongated sodium titanate nanotubes. XRD, SEM, HRTEM and BET analysis were employed to characterize the morphology and inner structure of the samples. The preparation conditions (the hydrothermal temperatures and the pH values of the solutions) of the obtained TiO₂ products were systematically studied. The maximum length of nanorod reaches to 1 μm while the lateral size could be limited less than 10 nm. The surface area can be easily tuned by modifying the stirring rate during the hydrothermal process. In addition, the photocatalytic performance of synthesized TiO₂ nanorods were also measured, and the nanorod structure with ultra-high surface area showed much better photocatalytic activity than the sample produced without stirring process, which can be attributed to the influence of the large difference in specific surface area of the obtained TiO₂ products.

Abstract: The ultra-low density carbon aerogel, as low as 20 mg/cm³, was fabricated by pyrolysis of the organic aerogel formed by aqueous condensation of resorcinol and formaldehyde. Its surface area was as high as 1783 m²/g and it was used for investigation of electrochemical capacitive behaviours. The ultra-low density carbon aerogel displayed capacitive performance (110 F/g at 0.2 A/g) in 6 M KOH aqueous solution. Additionally, over 98% of the initial capacitance was retained after repeating the cyclic voltammetry test for 1000 cycles. The electrochemical performance might be attributed to the combination of three dimensional “opened” structure and high surface area of the carbon aerogel.

Abstract: Bulk Ni-Mo-W hydrodesulfurization catalysts with high catalytic activity were synthesized via direct precipitation and controlled pH precipitation method, respectively. Analysis results shows that the preparation method has great influence on the morphology and pore structure, and further influence the hydrodesulfurization activity. The catalyst synthesized by controlled pH precipitation method has much higher surface area and pore volume, 132.9 m2/g and 0.30 mL/g, due to its developed porous structure accumulated by small crystal particles. The activity evaluation indicates that the bulk Ni-Mo-W hydrodesulfurization catalysts has good ultra-deep desulfurization activity of removing complex organic sulfur compounds, such as DBT and Cn-DBT.

Abstract: Tween 60 and Tween 80 as dispersant had been adding in the preparation process to increase the surface area of VPO catalysts. XRD、 XPS and TEM characterization tests show that the crystalline phase and the catalyst surface area of adding surfactant Tween 60 and Tween 80 are different from that did not. Although the two types of crystalline phase are to (VO)₂P₂O₇ but their microscopic structures are different and found that the surface area of the former is 35-40m² / g, while the surface area without adding surfactants is only 19m² / g.

Abstract: Pure anatase TiO₂ spheres with mesoporous structure were prepared by a simple urea assisted hydrothermal process at low temperature. The characterization of TiO₂ was examined by X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), N₂ adsorption-desorption and ultraviolet visible spectrophotometer (UV-VIS). The TEM and N₂ adsorption-desorption results confirmed that TiO₂ spheres has a mesoporous structure. The surface area of TiO₂ annealed at 400 °C is up to 302.3 m²/g with average pore diameter about 4.1 nm. While after annealed at 500 °C, the average pore diameter of TiO₂ is about 6.8 nm, but the surface area reduces to 142.6 m²/g

Abstract: Powders of tin dioxide (SnO2) have been prepared by two different modifications of wet chemical synthesis, i.e. (i) by conventional hydrolysis of tin chloride dissolved in aqueous ammonia solution and (ii) by precipitation from tin chloride dissolved in aqueous hydrazine monohydrate (N2H4*H2O) solution. The prepared gels were dried and then annealed at different temperatures varied from 300 to 700 oC in order to form nanocrystals. Structure and optical properties of the samples were investigated by using X-ray diffraction, transmission electron microscopy, thermoprogrammable hydrogen reduction, low temperature nitrogen adsorption method, photoluminescence, infra-red absorption, Raman spectroscopy, and X-ray photoelectron spectroscopy. The samples prepared by hydrazine-based method are characterized by surface area about 127-188 m2/g with high sintering resistance. The optical spectroscopy data revealed pure crystallinity and high defect concentration for the samples prepared by hydrazine-based method. The experimental results are discussed in view of different states of chemisorbed oxygen on SnO2 nanocrystal surfaces, which determine electronic and optical properties of the prepared samples.

Abstract: Hydroxyapatite (HAp) also shows the high absorption ability for proteins with low degradations. In this study, to modify the absorption ability and to obtain high surface area, metal ions (Zn, Mg, Fe) were introduced in preparing the HAp nanocrystals, and porous microparticles were subsequent fabricated by a spray drying method. HAp microparticles with Zn, Mg, Fe ions had a single phase of low crystalline HAp. The specific surface area of the HAp, Mg-HAp, Fe-HAp and Zn-HAp were 87, 150, 152, 167 m2/g, respectively. In the adsorption experiment of a lysozyme as a basic proteine, Zn-HAp showed the highest adsorption ability. On the other hand, the HAp microparticles witn metal ions showed higher adsorption ability for BSA as a acitic protein than pure HAp microparticles.