SiO2 Modification Research Articles

Large improvement of thermal transport and mechanical performance of polyvinyl alcohol composites based on interface enhanced by SiO2 nanoparticle-modified-hexagonal boron nitride

The interface plays a key role in determining the properties of polymer composites. However, chemical inertness of hexagonal boron nitride (h-BN) makes its surface modification troublesome. In this study, we, for the first time, used SiO2 as the modified molecular and investigated the effects of exfoliated h-BN and SiO2 nanoparticles-modified-exfoliated h-BN (SiO2@exfoliated h-BN) on the storage modulus, the glass transition temperature, the filler dispersion and the thermal conductivity of polyvinyl alcohol (PVA) composites prepared by a solution mixture method. The results showed that the SiO2 modification enhanced the interface interaction and improved the performance of the PVA composites. Based on the enhanced interface interaction by SiO2 modification and the aligned fillers in PVA by vacuum filtration, the high thermal conductivity of 13.88 W/m·K was realized at 15.2 wt% SiO2@exfoliated h-BN loading. Meanwhile, the tensile strength was also largely improved to 156 MPa, compared with 47 MPa of pure PVA. This study broadens the surface modification method of h-BN and provides a valuable reference for fabrication of high-performance thermal interface materials.

Fabrication and characterization of novel polyester thin‐film nanocomposite membranes achieved by functionalized SiO2 nanoparticles for gas separation

In this article, a new type of soluble polyester/silica (PE/SiO2) hybrid was prepared by the ultrasonic irradiation process. Surface modification of SiO2 was conducted using coupling agent γ‐glycidyloxypropyltrimethoxysilane (GOTMS) under ultrasonic irradiation. The structures of the modified hybrid nanocomposites were identified with a Fourier‐transform infrared spectroscopy (FT‐IR), whereas the size of the SiO2 in PE was characterized with a scanning electron microscope (SEM). SEM results indicated the formation and dispersion of nanometer scale size of inorganic domains inside the PE matrix due to the introduction of modified SiO2 and the interactions between organic and inorganic phases. The size of SiO2 particles in the modified system was about 25 nm. The transmission electron microscope (TEM) analysis showing the well‐dispersed nanosized titania nanoparticles (NPs). The densities and solubilities of the PE/SiO2 hybrids were also measured. Furthermore, thermal stability, residual solvent in the membrane film, and structural ruination of membranes were analyzed by thermal gravimetric analysis (TGA). Moreover, their mechanical properties were also characterized. It can be observed that the Young's moduli (E) of the hybrid films increase linearly with the silica content. The results obtained from gas permeation experiments showed that adding SiO2 to the PE membrane structure increased the permeability of the membranes. POLYM. ENG. SCI., 59:E237–E247, 2019. © 2018 Society of Plastics Engineers

SiO2-Modified Al2O3@Al-Supported Cobalt for Fischer–Tropsch Synthesis: Improved Catalytic Performance and Intensified Heat Transfer

SiO2-modified high thermal conductivity Al2O3@Al composites were synthesized and supported cobalt for Fischer–Tropsch synthesis to improve the catalytic performance and intensify the heat transfer within a fixed-bed reactor. FTS results showed that the CO conversion and C5+ selectivity increased whereas CH4 selectivity decreased, which could be attributed to the reduced metal–support interaction via modification of SiO2 on the surface of Al2O3@Al. The heat transfer coefficients of the Co/SAl2O3@Al–x were more than 30 times those of conventional Co/Al2O3 according to the laser flash measurement. The thermal conductive study showed that a homogeneous radial temperature gradient was maintained within the catalyst bed for Co/SAl2O3@Al-x even without using a heat diluter, indicating good thermal conductivity within the reactor. In addition, the temperature of the catalyst bed for Co/SAl2O3@Al-x was easier to reach a “steady state” compared to the reactor packed with traditional low thermal conductive Co/Al2O3,...

Esterification of Levulinic Acid to Levulinate Esters in the Presence of Sulfated Silica Catalyst

Levulinic acid (LA) is one of biomass derived building block chemicals with various applications. Catalytic esterification of LA with alkyl alcohol produces levulinate ester which can be applied as fragrance, flavouring agents, as well as fuel additives. In this study, a series of sulfated silica (SiO2) catalyst was prepared by modification of SiO2 with sulfuric acid (H2SO4) at different concentrations; 0.5 M to 5 M H2SO4. The catalysts were characterized, and tested for esterification of LA with ethanol to ethyl levulinate (EL). The effect of various reaction parameters including reaction time, catalyst loading and molar ratio of LA to ethanol on esterification of LA to EL were inspected. The catalyst with high concentration of acid sites seemed suitable for LA esterification to EL. Among the sulfated SiO2 catalysts tested (0.5 M-SiO2, 1 M-SiO2, 3 M-SiO2 and 5 M-SiO2), 3 M-SiO2 exhibited the highest performance with the optimum EL yield of 54% for reaction conducted at reflux temperature for 4 h, 30% 3 M-SiO2 loading and LA to ethanol molar ratio of 1:20. Besides, the reusability of 3 M-SiO2 catalyst for LA esterification with ethanol was examined for five cycles. Esterification of LA with methanol and 1-butanol were also carried out for methyl levulinate (ML) and butyl levulinate (BL) productions with 69% and 40% of ML and BL yields, respectively. This study demonstrates the potential of sulfated SiO2 catalyst for levulinate ester production from LA at mild process condition.

Bio-inspired fabrication of superhydrophilic nanocomposite membrane based on surface modification of SiO2 anchored by polydopamine towards effective oil-water emulsions separation

A new PVDF@pDA@SiO2 nanocomposite membrane was fabricated by virtue of the surface modification of polydopamine anchored SiO2 on PVDF membrane through a facile and eco-friendly preparation process. It possessed the superior superhydrophilicity/underwater superoleophobicity properties and presented the outstanding antifouling oil performance and high-efficiency separation ability for oil-water emulsions, which mainly resulted from its special surface micro-nano structure and pore induced capillarity phenomenon. Furthermore, the PVDF@pDA@SiO2 nanocomposite membrane also exhibited the splendid separation performance, regeneration ability and universality for various oil-water emulsions separation. In addition, the oil-water emulsion separation mechanism was discussed in depth. This work might provide a significant guidance for large-scale production and application of this nanocomposite membrane in the fields of wastewater recovery and drinking water treatment.

Strategic Synthesis of SiO2-Modified Porous Co3O4 Nano-Octahedra Through the Nanocoordination Polymer Route for Enhanced and Selective Sensing of H2 Gas over NO x.

In this work, a strategic synthesis of Co3O4 nano-octahedra was developed through the facile nanoscale coordination polymer (NCP) route, which was further modified by SiO2 to be used as a sensor for enhanced sensing of hydrogen. The Co(II)-NCP-derived Co3O4 octahedra and SiO2-modified Co3O4 octahedra were characterized using Fourier transform infrared, powder X-ray diffraction, Brunauer–Emmett–Teller, thermogravimetric analysis, field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed reduction (H2TPR) techniques. The SiO2-modified Co3O4 sensor exhibited a stronger and selective electrical response to H2 gas over NOx at 225 °C than Co(II)-NCP-derived Co3O4 octahedra and the conventional Co3O4 powder. The composite sensor shows faster recovery and significant repeatability than the other two. The enhancement in the sensing performance of the SiO2-modified Co3O4 octahedron was explained by the effectiveness of surface modification, controlled morphology, and combination of synergistic effect of Co3O4 and SiO2. Surface engineering of the as-prepared Co3O4 nano-octahedra with an exposed (111) surface plane and later SiO2 modification facilitates effective gas adsorption, resulting in enhancement in sensing and selectivity over NOx. The details of the synergistic effect and the plausible reasons for the improvement in gas-sensing parameters are discussed here. This study would offer new directions for development on the controlled synthesis of porous materials, in general, and in gas sorption or sensing, in particular.

Photoluminescence efficiency significantly enhanced by surface modification of SiO2 coating on β-sialon:Eu2+ phosphor particle

The surface modification on the β-sialon:Eu2+ phosphor particles was successfully achieved by the SiO2 coating via a sol-gel method. The photoluminescence (PL) intensity of the phosphor was effectively enhanced and dominantly depending on the homogeneity of the SiO2 coating. It was found that more homogeneous and smooth SiO2 coating was responsible for higher PL intensity. The strongest emission intensity was obtained after the SiO2 homogenously coating under an optimized preparation condition of tetraethoxysilane (TEOS):H2O = 1:1 in molar ratio by improving ∼39% of intensity compared to that of the uncoated β-sialon:Eu2+ phosphor, due to effective elimination on the surface groups of the phosphor particles. However, with increasing the molar ratio of TEOS:H2O, the PL intensity of the coated phosphor became deteriorated owing to the poor homogeneity in the coating layer, even became lower than that of the uncoated sample when TEOS:H2O = 1:40 in molar ratio. This technique would be potentially applied in various phosphors assembling for the white light-emitting diodes by significantly improving their photoluminescence efficiencies.

SiO2改质对转炉钢渣中C2S相优势析出及钢渣自粉化的影响

SiO2改质对转炉钢渣中C2S相优势析出及钢渣自粉化的影响

Facile synthesis of SiO2@TiO2 crystallite photocatalysts with enhanced interaction level and high light absorption efficiency

SiO2@TiO2 crystallite photocatalysts with TiO2 crystallite core and porous amorphous SiO2/TiO2 shell were synthesized as photocatalyst by one-pot hydrothermal process using tetrabutyl titanate (TBOT) complex and ethyl orthosilicate (TEOS) as Ti and Si sources, respectively. The synthesized SiO2@TiO2 crystallite photocatalysts were characterized by transmission electron microscopy, X-ray diffraction pattern, UV–Vis diffuse reflectance spectrum and N2 adsorption–desorption isotherm. The interaction between TiO2 and SiO2, which is associated with photocatalytically active centers, is significantly improved through an enlargement in the interfacial area and the optimization of SiO2 fraction. The SiO2 modification does not lower the light absorption efficiency of TiO2 crystallite core owning to the low reflectivity of porous SiO2/TiO2 shell but endows the photocatalyst with easy separation behavior from aqueous solution. Furthermore, the reciprocal inhibition in volume shrinkage of TBOT complex- and TEOS-derived gel networks, as a consequence of mineralization asynchronism, increases the specific surface area and pore volume of the formed SiO2/TiO2 shell. The enhanced photocatalytic activity of SiO2@TiO2 crystallite photocatalysts by SiO2 modification is mainly ascribed to an increase in the interaction level, the high light absorption efficiency of SiO2@TiO2 crystallite photocatalysts and an enlargement in specific surface area of SiO2/TiO2 shell.

Novel ferrocene-based ionic liquid supported on silica nanoparticles as efficient catalyst for synthesis of naphthopyran derivatives

We report synthesis of silica nanospheres containing ferrocene-tagged imidazolium acetate (SiO2@Im-Fc[OAc]) as efficient heterogeneous nanocatalyst for synthesis of naphthopyran derivatives under solvent-free conditions, based on modification of nano SiO2 by ionic liquid with ferrocene tags and subsequent anion metathesis reaction. The synthesized novel nanocatalyst (SiO2@Im-Fc[OAc]) was systematically characterized using Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, and field-emission scanning electron microscopy. The catalytic activity of (SiO2@Im-Fc[OAc]) was tested in one-pot three-component reaction of aromatic aldehydes, malononitrile, and 2-naphthol for facile synthesis of naphthopyran derivatives. To achieve high catalytic efficacy, the effects of various reaction parameters such as temperature, amount of catalyst, type of solvent, etc. were investigated. Furthermore, recovery and reuse of the nanocatalyst several times was demonstrated without appreciable loss in catalytic activity. The presented protocol offers several advantages, including green and ecofriendly nature, operational simplicity, higher yield, and easy recovery and reuse of the nanostructured catalyst. The workup of these very clean reactions involves only recrystallization of the product from ethanol and recovery of the catalyst by filtration.

Marrying the mussel inspired chemistry and Kabachnik–Fields reaction for preparation of SiO2 polymer composites and enhancement removal of methylene blue

The removal of organic dyes using functionalization SiO2 composites (denoted as SiO2-PDA-CSH) were prepared via a facile method that combined with mussel inspired chemistry and Kabachnik–Fields (KF) reaction. The size and surface morphology, chemical structure, thermal stability, surface charging property, and elemental composition were evaluated by means of transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), zeta potential, and X-ray photoelectron spectroscopy (XPS), respectively. The results demonstrated that the organic functional groups can be successfully introduced onto the surface of SiO2 microspheres through the combination of mussel inspired chemistry and KF reaction. The removal of cationic dye methylene blue (MB) by the raw SiO2 and SiO2-PDA-CSH composites was examined and compared using a series of batch adsorption experiments. The results suggested that SiO2-PDA-CSH composites had a 3-fold increase in the adsorption capacity towards MB than that of pure SiO2 microspheres and the adsorption process was dependent on the solution pH. According to the adsorption kinetics, the adsorption of MB onto SiO2-PDA-CSH composites was well described by pseudo-second-order kinetic model. The equilibrium data were fitted with Langmuir and Freundlich isotherm models with R2=0.9981 and R2=0.9982, respectively. The maximum adsorption capacity from Langmuir isotherm was found to be 688.85mg/g. The adsorption thermodynamics was also investigated in detailed. The parameters revealed that the adsorption process was spontaneous and endothermic in nature. The adsorption mechanism might be the synergistic action of physical adsorption of SiO2-PDA-CSH particles and electrostatic interaction between the MB and functional groups on the surface of SiO2-PDA-CSH composites, including sulfydryl, amino, aromatic moieties, and phosphate groups. Taken together, we developed a novel and facile strategy for the surface modification of SiO2 to achieve high adsorption towards MB based on the mussel inspired chemistry and multicomponent KF reaction. More importantly, this strategy could be easily extended for fabrication of many other high efficient adsorbents due to the universality of mussel inspired chemistry and various multicomponent reactions based on amino groups. Therefore, this work will open a new avenue and direction for the environmental applications of mussel inspired chemistry.

Improvement of hydrodeoxygenation stability of nickel phosphide based catalysts by silica modification as structural promoter

This study proposed a novel and facile approach to promote the stability of nickel phosphide (Ni2P) based catalysts by adding silica (SiO2) as structural promoter under hydrothermal condition. Catalytic hydrodeoxygenation (HDO) of triglyceride using soybean oil as model feed over Ni2P and palladium supported on α-Al2O3 (Ni2PPd/α-Al2O3) with and without SiO2 addition was conducted. With SiO2 modification, the catalyst was stable for 144h which is three times of that from the unmodified one, while higher than 99.0wt.% conversion was achieved with green diesel (i.e., C15-18 alkane) as the main products. H2-TPD, NH3-TPD, and XRD over fresh catalysts proved that SiO2 addition exhibited no distinguished effect on hydrogen chemisorption ability and active phase. XRD, TEM, XPS, EDX, XRF, H2-TPR, N2 physisorption, and TG/IR over fresh or/and spent catalysts demonstrated that SiO2 was a structural stability promoter (spacer), hindering the transformation of the active phase Ni2P. Furthermore, carbon deposition during the HDO process due to exist of metallic nickel was reduced with SiO2 addition. This work demonstrated that Ni2P supported on α-Al2O3 modified by SiO2 (Ni2PPd-SiO2/α-Al2O3) was a promising catalyst for the hydrodeoxygenation (HDO) of triglyceride to produce green diesel. With further work, it may lead to a catalyst capable for HDO in industry.

Study on the Super Hydrophobic Property of Bamboo by Gas Phase Nano SiO2 Modification

This paper is to explore a simple and effective experimental method to transform the bamboo’s hydrophobic property that enables them to achieve super hydrophobic effect. Soaking the experimental materials in nano-silicon dioxide solution is to prepare the super hydrophobic material. The particle size of silicon dioxide, contact angle of the transformed material, scanning electron microscope and energy spectrum were tested. The results show that the gas phrase nano-silicon dioxide solution is double microscopic particles which are advantageous to form the super hydrophobic structure. After transforming the property, both the contact angle of the outboard and inboard of bamboo can reach 150 degree or above, after transforming, there forms a super-hydrophobic thin film on the surface of bamboo material. The technology of forming a super hydrophobic structure on the surface of the gas phase nano-silicon dioxide is simple. This experiment is referentially meaningful in production.

Surface modification of SiO2 coated ZnO nanoparticles for multifunctional cotton fabrics

A simple chemical synthetic route was designed to prepare zinc oxide nanoparticles (ZnO-NPs) by using sodium alginate as anti-agglomeration agent in the presence of sodium hydroxide as alkali. Next, surface modification of ZnO-NPs with SiO2 nanoparticles was achieved as per to sol-gel process. Further enhancing of the multifunctional properties of SiO2@ZnO-NPs was conducted successfully thanks to (aminopropyl)triethoxysilan (APTES) and vinyltriethoxysilan (VTES) which, in turns, increase the affinity of the SiO2@ZnO-NPs nanocomposite towards glycosidic chains of cotton fabrics. Thorough characterizations of synthesized ZnO-NPs, SiO2@ZnO-NPs, SiO2@ZnO-NPs/APTES and SiO2@ZnO-NPs/VTES were conducted by the making use of well advanced techniques such as FT-IR, XRD, TEM, DLS and SEM-EDX. The data obtained clarified the formation of an interfacial chemical bond between ZnO and SiO2 as affirmed by FT-IR and XRD analysis. In addition, the results revealed by TEM, zeta sizer and SEM-EDX techniques, declared that the amorphous layers of SiO2, APTES or VTES evenly coated the surface of ZnO-NPs. For these nanocomposites, the work was extended to render cotton fabrics multifunctional properties such as antibacterial and UV protection with high durability even after 20 washing cycles using pad dry cure method. Taking the advantages of the silane compounds terminated by active groups such as OH, NH2, etc., open the door for further functionalization of the cotton fabrics’ surfaces by durable multifunctional agents applied in various applications.

Role of surface modification of SiO2 with bio-safe citric acid on the morphological and thermal properties of nanocomposites based on N-trimellitylimido-l-methionine diacid and 4,4′-diaminodiphenyl ether: using ultrasound irradiation and ionic liquid

In this work, the surface of SiO2 NPs was modified with citric acid (CA) to prevent agglomeration of SiO2 nanoparticles (NP)s in the poly(amide-imide) (PAI) matrix. The PAI was synthesized from polymerization reaction of N-trimellitylimido-l-methionine with 4,4′-diaminodiphenyl ether using molten tetra-n-butylammonium bromide and triphenyl phosphite. PAI–SiO2/CA nanocomposites (PSCN)s were prepared via a fast ultrasonic irradiation process. The PSCNs were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis.

Coesite inclusions in diamonds of Yakutia

The results of the study of diamonds with inclusions of high-pressure modification of SiO2 (coesite) by Raman spectroscopy are reported. It is established that the octahedral crystal from the Zapolyarnaya pipe is characterized by the highest residual pressure (2.7 ± 0.07 GPa). An intermediate value of this parameter (2.1 ± 0.07 GPa) was obtained for a crystal of transitional habit from the Maiskaya pipe. The minimal Raman shift was registered for coesite in diamond from the Komsomol’skaya–Magnitnaya pipe and provided a calculated residual pressure of 1.8 ± 0.03 GPa. The residual pressures for crystals from the placer deposits of the Kuoika and Bol’shaya Kuonamka rivers are 2.7 ± 0.07 and 3.1 ± 0.1 GPa, respectively. Octahedral crystals were formed in the mantle at a higher pressure than rhombododecahedral diamonds.

Crystallization of the Amorphous Phase in Foam Glass as a Method of Decreasing the Alkali-Silicon Reaction

The possibility of eliminating the alkali-silica reaction (ASR-interaction) in foam glass owing to crystallization of glass is examined. It is found that the main crystalline phases in the crystallization of the amorphous phase of foam glass are devitrite (Na2Ca3Si6O16), an octahedral phase (Na4CaSi3O9), and a cristobalitetridimite modification of SiO2. The binary glass ceramic composition of foam material shows significant ASR-interaction diminishment. The tile foam-glass-crystallite (Penosital®) can be glued or plastered with a cement-sand solution and covered with finishing polymer stuccos. The granular foam glass-ceramic can be successfully added as light aggregate to concrete without it disintegrating.

Synthesis of SiO2-Modified Li2MnO3-LiMn1/3Ni1/3Co1/3O2 by Spray Pyrolysis with Acid Addition as Cathode Materials for Lithium Ion Batteries

Lithium-rich layered solid solutions of Li2MnO3 and LiMO2, where M denotes at least one 3d transition metal, has attracted much attention as a cathode material of lithium ion batteries because they offer high capacities of around 250 mAh g-1 within the potential range of 2.0 to 4.8 V (versus Li/Li+). However, most of the works on the material have reported the electrochemical performance at low current rates. Arranging the crystal structures and morphologies of the materials is particularly important for improving the cell performance. Spray pyrolysis is a simple one-step synthesis technique to obtain various kinds of functional oxide powders. The particles prepared by spray pyrolysis have some advantages such as small particle size distribution, high purity, and easy control in composition and morphology of multi-component metal oxides. In addition, powder morphology can be controlled by acid addition to the starting solution of spray pyrolysis. We have found that a small amount of SiO2 addition remarkably suppressed the capacity fade of Li2MnO3-LiMn1/3Ni1/3Co1/3O2 prepared by spray pyrolysis during charge and discharge cycling. In this study, we investigated the effect of acid addition to the starting solutions of unmodified and the SiO2-modified Li2MnO3-LiMn1/3Ni1/3Co1/3O2 of spray pyrolysis. Stoichiometric amounts of lithium nitrate, manganese nitrate hexahydrate, nickel nitrate hexahydrate, cobalt nitrate hexahydrate were dissolved in deionized water with the addition of citric acid or boric acid. SiO2 aerosol was added to the solution. The reaction furnace consisted of four independent heating zones. Cycling tests were performed galvanostatically at a 0.1 C rate (1 C = 314 mAh g-1) between 2.0 and 4.8 V at 30ºC. The rate tests were performed by charging and discharging the electrode at 0.1 C for 5 cycles, 0.2 C for 5 cycles, 0.5 C for 5 cycles, and 1 C for 5 cycles. Prior to the cycling, a stepwise pre-cycling treatment was carried out by increasing the upper potential limit by 0.1 V from 4.5 V every two cycles to 4.8 V [1]. We investigated the capacity retention for 0, 2 and 5 wt.% SiO2-modified Li2MnO3-LiMn1/3Ni1/3Co1/3O2 samples at 0.1C in 1 M LiPF6/EC+DMC (1:2) after the stepwise pre-cycling treatment. The capacity fade on the cycling was successfully suppressed for all SiO2-modified samples. The highest capacity retention was obtained for the 2 wt.% SiO2-modified sample. SEM images showed that the as-synthesized particles were not agglomerated and had spherical shapes. After heat-treatment, the particles retained their shapes. The spherical shapes were partially collapsed by SiO2 modification. The interior primary particle size was more grown than those of the unmodified particles. The specific surface area slightly decreased with SiO2 content to 2 wt.%. The specific surface area increased at a SiO2 content of 5 wt.% and this may be due to the collapsed shape compared with other particles. We synthesized the SiO2-modified Li2MnO3-LiMn1/3Ni1/3Co1/3O2 using the starting solutions containing various amounts of boric acid. SEM images showed that boric acid increased the densities of the materials by acting as a sintering agent. With more than 0.5 wt.% boric acid addition, Li2MnO3-LiMn1/3Ni1/3Co1/3O2 powders displayed aggregated structures and large sizes. Improvement of the densities of the materials means the decrease of the isolated particles observed in the case of the SiO2-modified Li2MnO3-LiMn1/3Ni1/3Co1/3O2, which may lead to the enhancing the electrochemical performance. Moreover, we synthesized the unmodified and SiO2-modified Li2MnO3-LiMn1/3Ni1/3Co1/3O2 using the starting solutions containing various amounts of citric acid. SEM images showed that most of the particles had spherical shapes but some particles were collapsed. The specific surface area of the synthesized Li2MnO3-LiMn1/3Ni1/3Co1/3O2 from the starting solutions containing citric acid is much higher than that of the unmodified and SiO2-modified Li2MnO3-LiMn1/3Ni1/3Co1/3O2. For example, the specific surface area of the as-synthesized Li2MnO3-LiMn1/3Ni1/3Co1/3O2 using the solution containing 0.93 mol l-1 of citric acid is 28 m2 g-1. Higher specific surface area is expected to favor the high rate capability. It can be found from the above results that boric acid and citric acid are effective in controlling the powder morphology. We will present the electrochemical properties including rate capability. [1] A. Ito, D. Li, Y. Ohsawa, Y. Sato, J. Power Sources 183 (2008) 344-346.

High sensitivity biosensors based on germanium nanowires fabricated by Ge condensation technique

We demonstrate a novel technique to fabricate germanium nanowires (GeNWs) for field effect transistor biosensors. Arrays of core-shell structure GeNWs were “top-down” fabricated by combining the complementary metal-oxide semiconductor (CMOS) compatible technology and Ge condensation technology. The obtained GeNWs had stable SiO2 cladding, which acted as good modification platform for biochemical detection, since SiO2 modification was a mature technology. After the GeNWs were covalently bonded with DNA probe, the nanosensor demonstrated highly sensitive concentration-dependent current change in response to target DNA. This study may pave the way for further application such as the integration of bioelectronics and biosensors with the attractive semiconductor material Ge in future work.

Research of Chemical Pre-treatment Created by Sol-gel Process on the Polished Surface of Aluminium Substrate

This paper reports the preparation and characterization of thin transparent nanolayers with phase composition ZrF4 and different modification of SiO2 with special focus on the affecting the surface roughness of the material and the way of exclusion of the thin nanolayer on the surface of the polished aluminium material. The thin nanolayer was prepared by the sol-gel method. The final treatment based on PTFE was applied on the surface of some samples. This treatment is suitable for the increasing of the wear resistance. The films were characterized with help of SEM microscopy and EDS analysis. The surface roughness was measured with classical surface roughness tester. There was published results on this theme but not on the polished surface of the aluminium material. The results from the experiment shows on the problems with application of these nanolayers because there were found a cracks on the surface of the material and deformations of the layer after application of two nanoproduts and PTFE final layer. The surface layer formation is discussed.