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1.
NiO-In2O3 composite nanofibers are synthesized via electrospinning and calcining techniques.Micro-sensors are fabricated by sputtering Pt electrodes on Si chips to form sensor substrates,and then spinning the NiO-In2O3 composite nanofibers onto the sensor substrate surface.The as-fabricated micro-sensors exhibit excellent H2S sensing properties at room temperature.The sensitivity of the micro-sensors is up to 6 when the sensors are exposed to 3μL/LH2S,and the corresponding response and recovery times are 14 and 22 s,respectively.The micro-sensors also exhibit high selectivity and good stability.Especially,the micro-sensors can operate at various humidity conditions.The sensitivity of the micro-sensors is 3.8 to 3μL/LH2S at 75% relative humidity.These characteristics make the micro-sensors good candidates for practical H2S sensors with high performance. 相似文献
2.
Preparation and radar-absorbing properties of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/TiO<Subscript>2</Subscript>/Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/Yb<Subscript>2</Subscript>O<Subscript>3</Subscript> composite powder
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Yi-fan Zhang Zhen Ji Ke Chen Cheng-chang Jia Shan-wu Yang Meng-ya Wang 《矿物冶金与材料学报》2017,24(2):216-221
Al2O3/TiO2/Fe2O3/Yb2O3 composite powder was synthesized via the sol-gel method. The structure, morphology, and radar-absorption properties of the composite powder were characterized by transmission electron microscopy, X-ray diffraction analysis and RF impedance analysis. The results show that two types of particles exist in the composite powder. One is irregular flakes (100-200 nm) and the other is spherical Al2O3 particles (smaller than 80 nm). Electromagnetic wave attenuation is mostly achieved by dielectric loss. The maximum value of the dissipation factor reaches 0.76 (at 15.68 GHz) in the frequency range of 2-18 GHz. The electromagnetic absorption of waves covers 2-18 GHz with the matching thicknesses of 1.5-4.5 mm. The absorption peak shifts to the lower-frequency area with increasing matching thickness. The effective absorption band covers the frequency range of 2.16-9.76 GHz, and the maximum absorption peak reaches -20.18 dB with a matching thickness of 3.5 mm at a frequency of 3.52 GHz. 相似文献
3.
Xinxin Tan Wenjie Peng Meng Wang Gui Luo Zhixing Wang Guochun Yan Huajun Guo Qihou Li Jiexi Wang 《自然科学进展(英文版)》2023,33(1):108-115
Nickel-rich and cobalt-free cathode materials have obvious advantages in the aspects of energy density and economic efficiency. However, these materials are restricted from being used in commercial lithium-ion batteries due to the problems of poor structural stability and rate capability. In this study, the aluminum and zirconium dual-doped Co-free Ni-rich LiNi0.96Mn0.04O2cathode material(NMAZ) is prepared by a facile high-temperature solid-phase method. The obta... 相似文献
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Biao Wang YuDong Zhao LiMing Hu JunSheng Cao FengLi Gao Yun Liu LiJun Wang 《科学通报(英文版)》2010,55(3):228-232
Cu-doped TiO2 nanofibers with an average diameter of about 80 nm are synthesized through an electrospinning method. Both anatase and rutile crystallographic structures are found in the fibers based on XRD results. Compared with pure TiO2 nanofibers, the Cu-doped TiO2 nanofibers exhibit improved CO sensing properties at 300°C. The sensitivity of Cu-doped TiO2 nanofibers is up to 3 when the sensor is exposed to 5 ppm CO, and the response and recovery times are about 4 and 8 s, respectively. Good selectivity i... 相似文献
6.
Nanometer ferromagnetic metal-semiconductor matrix Fe−In2O3 granular films are fabricated by the radio frequency sputtering. Magnetic properties and the giant magnetoresistance (GMR)
effect of Fex(In2O3)1−x granular film samples are studied. The result shows that the magnetoresistance (MR) ratio Δρ/ρ
0 value of the granular film samples with Fe volume fraction x=35% is 4.5% at room temperature. The temperature dependence (T=1.5–300 K) of the MR ratio Δρ/ρ
0 value of Fe0.35(In2O3)0.65 granular films shows that Δρ/ρ
0 value below 10 K increases rapidly with the decrease of the temperature, and when T=2 K, Δρ/ρ
0 value is 85%. Through the study of the dependence of low field susceptibility on temperature and the hysteresis loops at
different temperatures, it has been found that, when the temperature decreases to a critical point T
p=10 K, the change of the structure in Fe0.35)In2O3)0.65 granular films results in the transformation of state from ferromagnetic to spin-glass-like. The remarkable increase of the
MR ratio Δρ/ρ
0 value of Fe0.35(In2O3)0.65 granular films below 10 K seems to arise from the peculiar conducting mechanism of the granular film samples in the spin-glass-like
state. 相似文献
7.
MA JianZhong WANG Wei LIU HongJie CHEN Yue XU XiaoBin LELIEVELD Jos 《科学通报(英文版)》2013,58(34):4329-4336
Strong pollution emissions from large urban and industrial centres in eastern China are thought to greatly impact regional air quality and global atmospheric chemistry.In this study,we investigate extensive pollution plumes over North China,observed by aircraft during the IPAC-NC(Influence of Pollution on Aerosols and Cloud Microphysics in North China)field campaign in spring 2006.Several pollution plumes were encountered,characterized by sharp and strong increases of SO2and NOx(NO plus NO2)as well as remarkable O3variability.During a flight performed downwind of the megacity Tianjin on 9 April,O3was found to be depleted at NOx>15 ppbv and enhanced at NOx mixing ratios of 6–7 ppbv.Our analysis indicates that the plumes had recently been released by industrial plants,and partly mixed with urban emissions,giving rise to the large-scale transport of air pollution and substantial degradation of air quality. 相似文献
8.
A series of Ni, Sn and Ca modified Pd/TiO2-Al2O3 catalysts were prepared by the incipient wetness impregnation method and their catalytic performance for the selective catalytic reduction of NOx by H2 was evaluated. The results showed that the NOx conversion and N2 selectivity were improved over Pd-Sn/TiO2-Al2O3 and Pd-Ni/TiO2- Al2O3 catalysts above 200 ℃. More importantly, the N2 selectivity and high-temperature activity of Pd-Sn/TiO2- Al2O3 catalyst was far superior to the single Pd/TiO2-Al2O3 catalyst. The optimal Sn loading was 2 wt.%. X-ray diffrac- tion (XRD) results showed that the interaction between Pd and Sn promotes the dispersion of Pd over TiO2-Al2O3. Temper- ature-programmed reduction (Ha-TPR) results demonstrated that the addition of Sn contributes to the formation of PdO and improving the redox property of Pd/TiOz-Al2O3. The addi- tives of Ni and Sn also facilitated the absorption of NOx and the oxidation of NO to NOa, which play important roles in the selective catalytic reduction of NOx by hydrogen. 相似文献
9.
V2O5/TiO2 composite films were prepared on pure titanium substrates via micro-arc oxidation (MAO) in electrolytes consisting of NaVO3. Their morphology and elements were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis. Phase composition and valence states of species in the films were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS) were also employed to evaluate the photophysical property of the films. The V2O5/TiO2 composite films show a sheet-like morphology. Not only V2O5 phase appears in the films when the NaVO3 concentration of the electrolyte is higher than 6.10 g/L and is loaded at the surface of anatase, but also V4+ is incorporated into the crystal lattice of anatase. In comparison with pure TiO2 films the V2O5/TiO2 composite films exhibit significantly narrow band gap energy. The film prepared in an electrolyte consisting of NaVO3 with a concentration of 8.54 g/L exhibits the narrowest band gap energy, which is approximately 1.89 eV. The V2O5/TiO2 composite films also have the significantly enhanced visible light photocatalytic activity. The film prepared in an electrolyte consisting of NaVO3 with a concentration of 8.54 g/L exhibits the best photocatalytic activity and about 93% of rhodamine is degraded after 14 h visible light radiation. 相似文献
10.
Qingcheng Liang Di Li Shang Gao Dayong Jiang Jianxun Zhao Jieming Qin Jianhua Hou 《科学通报(英文版)》2014,59(4):447-451
Micro-sensors are fabricated by co-electrospin- ning In203 and SnO2 nanofibers on the substrates of SiO2/Si with interdigitated Pt signal electrodes. The total sensor area is 1.36 mmx 0.55 mm and the active area is only 0.63 mmx 0.55 ram. Excellent NH3 sensing properties are obtained based on the sensors at room temperature. The sensitivity is at most 28 when the sensors are exposed to NH3 of 10 ppm. The response time is 8 s or so and the recovery time is nearly 2 s. Not only fine selectivity, but also long- time stability is obtained. The results not only demonstrate the obtained micro-sensors are very promising devices for NH3 detection, but also show a possible route for large-scale NH3 sensor fabrication at the industrial level. 相似文献
11.
The ozone formation reactivity of ethanol has been studied using chamber experiments and model simulations. The computer simulations are based on the MCM v3.1 mechanism with chamber-dependent auxiliary reactions. Results show that the MCM mechanism can well simulate C 2 H 5 OH-NO x chamber experiments in our experimental conditions, especially on ozone formation. C 2 H 5 OH-NO x irradiations are less sensitive to relative humidity than alkane species under our experimental conditions. In order to well simulate the experiments under high relative humidity conditions, inclusion of N 2 O 5 +H 2 O=2HNO 3 in the MCM mechanism is necessary. Under C 2 H 5 OH-limited conditions, the C 2 H 5 OH/NO x ratio shows a positive effect on d(O 3 -NO)/dt and RO 2 +HO 2 . High C 2 H 5 OH/NO x ratios enhance the production of organoperoxide radical and HO 2 radical concentrations, which leads to a much quicker accumulation of ozone. By using ozone isopleths under typical scenarios conditions, the actual ozone formation ability of ethanol is predicted to be 2.3-3.5 part per billion (ppb) in normal cities, 3.5-146 ppb in cities where ethanol gas are widely used, and 0.2-3.2 ppb in remote areas. And maximum ozone formation potential from ethanol is predicted to be 4.0-5.8 ppb in normal cities, 5.8-305 ppb in cities using ethanol gas, and 0.2-3.8 ppb in remote areas. 相似文献
12.
采用粉末冶金法制备Li5La3Ta2O12/Al基陶瓷复合材料,并评价其阻尼性能、硬度和屈服强度.结果表明,复合材料的室温阻尼和力学性能较纯Al具有显著提高.当陶瓷颗粒质量分数为20%时,复合材料的室温内耗值可达0.010, 比相同温度范围内Al的内耗高约1个量级,对应的屈服强度和硬度值分别比Al提高约43%和28%. 相似文献
13.
氧化吸收法同步脱除燃烧烟气中SO2,NOx和CO2的化学热力学及其评价 总被引:1,自引:0,他引:1
湿化学法同步脱除烟气中气态污染物是燃烧源大气污染控制的重要方法之一,为探究采用不同氧化吸收策略同时脱除燃烧烟气中SO_2,NO_x和CO_2的可行性,基于化学热力学原理,分析了9种联合氧化吸收策略的性能,具体的氧化吸收策略包括:H_2O_2-NH_3·H_2O,H_2O_2-MDEA,H_2O_2-NaOH,O3-NH_3·H_2O,O3-MDEA,O3-NaOH,NaClO_2-NH_3·H_2O,NaClO_2-MDEA和NaClO_2-NaOH,并提出新的动态加权法对其性能进行综合评价。结果表明:上述所有策略均具有SO_2,NO_x和CO_2捕获的可行性。O3-NaOH,NaClO_2-MDEA和NaOH做吸收剂的氧化吸收溶液分别对单一脱硫、脱硝和脱碳效果最好。当综合考虑同步脱除SO_2,NO_x和CO_2时,NaClO_2-MDEA优于其他策略,其结果可为燃烧烟气中的气体污染物的联合脱除提供参考。 相似文献
14.
Magnetically recyclable photocatalysts with efficient performances under visible light were synthesized by combining Fe_3O_4/ZnO with BiOI and polyaniline(PANI). The FT-IR, XRD, HRTEM, SEM, EDX, XPS, UV–vis DRS,VSM, BET, and PL instruments were utilized for characterization of the as-prepared products. The activity tests exhibited that the superior rate constant in photocatalytic performance was achieved over the Fe_3O_4/ZnO/BiOI/PANI(20%) nanocomposite, which enhanced for more than 59.9, 10.0, and 6.57 times, as compared to those of the Fe_3O_4/ZnO, Fe_3O_4/ZnO/PANI, and Fe_3O_4/ZnO/BiOI photocatalysts in degradation of RhB, respectively.Successful photocatalytic degradations of MO/MB and photo reduction of Cr(VI) were also investigated to confirm the potential application of the photocatalyst in removal of various pollutants. The considerably enhanced activity pointed to a promoting effect of p-n-p heterojunctions formed between PANI, ZnO, and BiOI, and improved textural characteristics, which are benefit for improvement of the photocatalytic performances. 相似文献
15.
The interactions between NO, O2 and their mixture on BaAl2O4, as well as the reaction of NOx with soot in the presence of O2, have been investigated using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). NO adsorption produces only nitrites species in the absence of O2. NO2 adsorption produces nitrates species besides nitrites species. The produced nitrites will further react with O2, Osurf^-. and Olattice^2- to form nitrates. The reaction of NOx with soot begins with the reaction of nitrates with soot oxygenated complex (C(O)), which is regarded as the key and rate determining step. A reaction pathway is proposed for the catalyzed reaction of NOx with soot in the presence of O2. 相似文献
16.
室温全固态氢传感器研究 总被引:2,自引:0,他引:2
以Sb2O5-H2O-H3PO4 复合氧化物为固态电解质 ,利用混合压膜和蒸发的方法制作传感催化电极和参考电极 ,研制了室温全固态电解质氢气传感器。传感器的组成为:空气 ,Pd(或Ag) |Sb2O5-H2O-H3PO4 |Pd ,H2 (在N2 或空气中) ,考察了传感器的电位响应值与氢气体积分数之间的关系 ,以及温度对氢气传感性能的影响;通过测绘极化曲线来研究其应答机理,从而分析传感器电位响应值不同于能斯特值的原因——敏感电极上混合电势的形成。 相似文献
17.
Synthesis of highly ordered SnO2/Fe2O3 composite nanowire arrays by electrophoretic deposition method 总被引:1,自引:0,他引:1
LIJianjun ZHANGXingtang CHENYanhui LIYuncai HUANGYabin DUZuliang LITiejin 《科学通报(英文版)》2005,50(10):1044-1047
Highly ordered SnO2/Fe2O3 composite nanowire arrays have been synthesized by electrophoretic deposition method. The morphology and chemical composition of SnO2/Fe2O3 composite nanowire arrays are characterized by SEM, TEM, EDX, XPS, and XRD. The results show that the SnO2/Fe2O3 composite nanowires are about 180 nm in width and tens of microns in length, and they are composed of small nanoparticles of tetraganal SnO2 and rhombohedral α-Fe203 with diameters of 10-15nm. The SnO2/Fe2O3 composite nanowires are formed by a series of chemical reactions. 相似文献
18.
《自然科学进展(英文版)》2022,32(1):128-134
Solid oxide fuel cells (SOFCs) technology, with fuel flexibility, is one of the most promising power generation technology. However, the high operating temperature of SOFCs has hindered their commercial applications. As a crucial requirement to enhance its performance, SOFCs electrolytes should operate at a low temperature. Carbonate/ceria composites are developed as electrolytes for low operating temperature SOFCs, and a better understanding of the mechanism of its ionic conductivity serves this purpose. In this work, ceria-carbonate composite electrolyte, Na2CO3/samarium doped ceria (NSDC) were synthesized by the co-precipitation method. The synthesized electrolytes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV–Vis spectroscopy. The XRD and SEM results showed that the sintered NSDC nanocomposite comprised a single-phase dense electrolyte structure. The crystallite size of the NSDC nanocomposite was greatly affected by the different pre-firing temperatures and different sintering temperatures. Also, the ionic conductivity of the prepared NSDC nanocomposite electrolytes was strongly dependent on the pre-firing and sintering temperatures. The NSDC nanocomposite electrolytes were pre-fired at 950 ?°C and 650 ?°C and sintered at 1200 ?°C and 900 ?°C respectively, had ionic conductivity in H2 and air high as 0.36 ?S/cm and 0.3 ?S/cm. 相似文献
19.
High-capacity anode materials have stimulated much attention to developing high-performance lithium-ion batteries. However, high-capacity anode materials commonly suffer from the pulverization matter that greatly hinders their practical applications, especially in terms of the high proportion of active materials. In this work, a Ga2O3nanowire electrode is synthesized by thermal evaporation and immediately used as an anode without the aid of binders and conductive additives.... 相似文献
20.
对Al的质量分数分别为0.20%,0.35%,0.60%的Cu-Al合金粉末进行内氧化,得到Cu-Al2O3粉末。采用化学气相沉积法在Cu-Al2O3粉末表面原位生长碳纳米管(carbon nano tubes, CNTs),采用放电等离子烧结工艺成功制备了CNTs/Cu-Al2O3复合材料。采用扫描电子显微镜和透射电子显微镜观察了CNTs/Cu-Al2O3复合粉末、复合材料断口的形貌。采用显微硬度计、微拉伸试验机、摩擦磨损试验机分别对纯Cu及复合材料的维氏硬度、抗拉强度、摩擦因数进行测试。采用电化学工作站测试复合材料在3.5%NaCl (质量分数)水溶液中的耐腐蚀性能。结果表明,随着Al的质量分数的增加,粉末表面合成的CNTs的数量也增多。Al的质量分数为0.35%时,CNTs/Cu-Al2O3复合材料的综合性能最佳,与纯Cu相比,复合材料的抗拉强度和腐蚀电势分别提高了86.4%和43.2%,分别为315 MPa和-0.268 V,摩擦因数降低了53.3%,仅为0.28。 相似文献