基质调控合成枝状碳酸钙及羟基锡酸锌包覆碳酸钙

以十六烷基三甲基溴化铵(CTAB)为有机模板,加入到丙三醇和水的混合溶液中制备碳酸钙并在其母液中进一步合成羟基锡酸锌包覆碳酸钙。通过XRD,SEM,TG-DSC分别对产物的晶型、形貌、热解行为进行了分析,并研究了CTAB浓度对碳酸钙的形貌和晶体结构的影响。结果表明:碳酸钙为枝状文石型碳酸钙,羟基锡酸锌较好的包覆在枝状碳酸钙表面,当CTAB质量浓度为2.2 g/L时,枝状晶体形态最好。     

水热法制备Ag-In_2O_3纳米粉体及其甲醛气敏性能

通过简单的水热反应,结合煅烧工艺制备了不同掺杂浓度(摩尔比0%-8%)的系列Ag-In_2O_3纳米颗粒。通过扫描电子显微镜(SEM)和X射线衍射仪(XRD)对制备的样品形貌和物相进行分析,并对其进行了甲醛气敏性能测试。实验结果表明:得到的粉体为形貌不规则的纳米颗粒;未掺杂的样品为立方相In_2O_3,掺杂的样品为单质Ag和立方相In_2O_3的混合物;4%掺杂的Ag-In_2O_3对应的传感器对甲醛的气敏性能最好。文章简单分析了样品的生长机理,并用Wolkenstein’s模型解释了样品对甲醛的敏感机理。     

一种新型气敏元件的研究

本文报道了复氧化物偏锡酸锌多晶体的合成工艺及以其为基体材料制作的新型(QM—Y1型)气敏元件的敏感特性和制备工艺,并讨论了敏感机理研究表明,这种气敏元件具有灵敏度高、稳定性好、响应时间与恢复时间短、电导率变化大等优点,可作为可燃性气体检测、检漏、监控和报警等设备中的理想探头。     

微波水热法制掺铈SnO_2纳米气敏材料及其性能

采用微波水热法制备SnO2纳米粉体,应用X射线衍射(XRD)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)对粉体进行结构表征和微观形貌观察;以所得粉体为原料制备厚膜气敏元件,对其进行气敏性能测试。结果表明:铈离子(Ce3+)的掺杂对SnO2晶粒的生长有抑制作用,掺杂后颗粒粒径约为50 nm;前驱体煅烧温度为700℃时,Ce3+的掺杂可改变SnO2气敏元件对某些气体的灵敏度,当工作温度为370℃时,掺杂x(Ce3+)=5%的气敏元件对乙醇的灵敏度达到20.5,对丙酮的灵敏度达到22,均高于未掺杂Ce3+的气敏传感器的灵敏度;Ce3+的掺杂可以降低厚膜气敏元件的本征电阻,提高其工作稳定性。     

rGO/Ce掺杂SnO_2复合纳米纤维的制备及H_2S气敏性能研究

采用静电纺丝法制备还原氧化石墨烯(rGO)/SnO_2复合纳米纤维,研究了Ce掺杂及掺杂量对rGO/SnO_2纳米纤维的微结构与气敏性能的影响.利用扫描电子显微镜(SEM)、透射电子显微镜(TEM,带SAED)、X射线衍射仪(XRD)及拉曼光谱仪(Raman)对复合纳米纤维的结构与形貌进行表征.结果表明:不同含量Ce掺杂对复合纳米纤维的晶体结构和形貌均无明显影响.气敏测试结果表明:不同的Ce掺杂量均能改善rGO/SnO_2纳米纤维对H_2S的灵敏度,在Ce掺杂摩尔分数为3%时复合材料对H_2S具有最佳的气敏性能,在75℃时5μL/L H_2S气体的灵敏度高达300,同时选择性和响应恢复性能也均有显著提高.     

铝掺杂ZnO基纳米棒气敏传感材料制备及其LPG气敏性能

采用两步化学溶液法制备了ZnO和Al-ZnO纳米棒,利用扫描电子显微镜(FE-SEM)(JSM-6700F,Japan)和X射线衍射仪(XRD)(Rigaku D/Max 2500PC,Japan)进行表面形貌表征和结构分析.气敏测试结果表明,Al-ZnO纳米棒元件在380℃下对500和2 000×10-6液化石油气(LPG)的灵敏度分别为9.5和21,掺杂Al3+能有效提高ZnO纳米阵列元件对LPG的气敏性能.     

ZnO/SnO复合纳米棒的水热合成及气敏研究

运用水热法合成六方纤锌矿ZnO纳米棒,在ZnO纳米棒表面水热生长SnO,获得了表面疏松的ZnO/SnO复合纳米棒材料。运用X射线粉末衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、电子能谱(EDS)等手段表征了该材料的形貌和组成。BET氮吸附测试表明其表面疏松结构具有11.38 m2/g的比表面积。气敏实验证明了该材料对甲醛气体具有百万分率浓度级检测灵敏度,对于开发甲醛传感材料具有理论意义和潜在应用价值。     

新型碳纳米管复合薄膜材料的气敏性能

采用射频反应磁控溅射锡(Sn)靶和钨(W)靶的方法制备了SnO2/WO3/MWCNT复合薄膜材料和相应的气敏传感器,通过FSEM、XRD和XPS等方法分析了复合薄膜材料的横断面表面形貌、物相结构及表面化学组成,测试了该气敏传感器的灵敏度、选择性和响应恢复等气体敏感性能.实验结果表明:该复合薄膜气敏传感器具有较好的气敏性能,对NO2有较好的灵敏度,对其他干扰气体不敏感;SnO2/WO3/MWCNT薄膜中,W、Sn、C主要以W+6、Sn+4和C的形式存在.文中还对气敏响应机理进行了初步的分析与讨论.     

核-壳结构SiO2@α-Fe2O3亚微米球的制备及性能研究

采用两步溶胶-凝胶法制备了单分散、球形、亚微米级、壳层厚度可调的核-壳结构SiO2@α-Fe2O3亚微米球.借助X-射线衍射仪(XRD)、扫描电子显微镜(SEM)和紫外可见光谱仪(UVS)对结果样品的纯度、结构、形貌、尺寸和光催化性能进行了表征,探讨了样品的形成机理和光催化机理.实验结果表明,制备的样品由亚微米级(平均粒径400nm)SiO2核和粒径约为30nm的壳通过羟基键合作用连接而成,并显示出很强的光催化性能.     

类八面体BaMoO4微晶的熔盐法合成

通过熔盐法,以NaNO3为熔盐介质制备纯相BaMoO4微晶.考察合成温度、反应时间及熔盐含量对产物结晶度、粒径及形貌的影响.采用X线衍射仪(XRD)和扫描电子显微镜(SEM)对微晶进行表征.结果表明:在各种反应条件下都能得到纯的四方相白钨矿结构BaMoO4微晶,且结晶性良好.合成温度及反应时间对产物的形貌有明显影响,随着合成温度的升高和反应时间的延长,晶粒尺寸分布缩小,形貌规整且呈类八面体.熔盐含量对BaMoO4微晶尺寸影响显著,随着熔盐含量增多,晶粒的平均尺寸缩小.制备形貌规整且尺寸较小的BaMoO4微晶适宜条件为NaNO3与Na2 MoO4的摩尔比=10∶1时在500℃下保温4h.     

Formation of highly crystalline maghemite nanoparticles from ferrihydrite in the liquid phase

Fe₅O₇(OH)·4H₂O ferrihydrite is a low-crystallinity antiferromagnetic material. γ-Fe₂O₃ (maghemite) magnetic nanoparticles were prepared from a ferrihydrite precursor, by chemically induced transformation in FeCl₂/NaOH solution. The magnetization, morphology, crystal structure and chemical composition of the products were determined by vibrating sample magnetometry, transmission electron microscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy (XPS). Ferrihydrite underwent aggregation growth and transformed into α-FeO(OH) (goethite) particles, which subsequently transformed into γ-Fe₂O₃ nanoparticles, that became coated with NaCl. The γ-Fe₂O₃ particles had a flake-like morphology, when prepared from 0.01 mol/L FeCl₂ and a FeCl₂:NaOH molar ratio of 0.4. The γ-Fe₂O₃ particles were more spherical, when prepared from a FeCl₂:NaOH molar ratio of 0.6. The Fe content of the flake-like particles was lower than that of the spherical particles. Their magnetizations were similar, and the coercivity of the flake-like particles was larger. The differences in morphology and magnetization were attributed to the surface effect, and the difference in coercivity to the shape effect.     

A review on TiO2 nanotube arrays: Fabrication, properties, and sensing applications

Fabrication, properties, and sensing applications of TiO₂ nanotubes have been reviewed, and the highly ordered TiO₂ nanotube arrays made by anodic oxidation in fluoride-contained electrolytes highlighted. The effect of anodization parameters (electrolyte, pH, and voltage) on the titania nanotube size and shape were discussed. The excellent biocompatibility of TiO₂, the high orientation, the large surface area with tunable pore sizes, as well as the high electron transfer rate along with the nanotubes make TiO₂ nanotube array an ideal substrate for the sensor’s fabrication and application. The sensors based on the TiO₂ nanotube arrays for sensing hydrogen, oxygen, humidity, glucose and hydrogen peroxide all exhibited low detection limit, high stability, very good reproducibility and high sensitivity.     

Tunable tribological properties in water-based lubrication of water-soluble fullerene derivatives via varying terminal groups

In this paper,three kinds of water-soluble fullerene derivatives were synthesized via electrophilic addition reaction and cycloaddition reaction,respectively.The chemical composition characterizations of these derivatives indicated the successful preparation of C60(OH)x,C60(C(COOH)2)x and C60(OH)x(NHCH2COOH)y fullerene derivatives.The aggregation and morphology characterizations showed that the three kinds of derivatives had an ideal spherical aggregating structures and excellent dispersibility in water,especially C60(OH)x and C60(C(COOH)2) x.The lubrication performance of the fullerene derivatives acted as lubricant additives were investigated at different concentrations in the range of 0-1 wt%.The results indicated that the addition of polyhydroxyl and carboxylic derivatives could improve the lubrication properties,which led to the reduction of wear to about 40% at most.It is attributed that the optimized substitutions of fullerene molecules may be of benefit to their distribution properties and lubricating behaviors in water based lubrication.     

Synthesis of nanocrystalline NiCrC alloy feedstock powders for thermal spraying by cryogenic ball milling

Nanocrystalline NiCrC alloy powders with a qualified particle size distribution for thermal spraying were synthesized using the cryogenic ball milling (cryomilling) method. The morphology, microstructure, size distribution, and phase transformation of the powders were characterized by scanning electron microscopy (SEM), laser scattering for particle size analysis, X-ray diffraction (XRD), and transmission electron microscopy (TEM). After cryomilling for 20 h, the average grain size of the as-milled powders approached a constant value of 30 nm by XRD measurement. The average particle size slightly increased from 17.5 to 20.3 μm during the 20-h milling. About 90vol% of the powders satisfied the requirement for thermal spraying with the particle dimension of 10-50 μm, and most of the powders exhibited spherical morphology, which were expected to have good fluidity during thermal spraying. The Cr₂O₃ phase formed during the cryornilling process as revealed in the XRD spectra, which was expected to enhance the thermal stability of the as-milled powders during the followed thermal spraying or other heat treatment.     

Sonochemical synthesis of nanostructured nickel hydroxide as an electrode material for improved electrochemical energy storage application

A facile and fast approach for the synthesis of a nanostructured nickel hydroxide(Ni(OH)_2) via sonochemical technique is reported in the present study. The X-ray diffraction results confirmed that the synthesized Ni(OH)_2 was oriented in β-phase of hexagonal brucite structure. The nanostructured Ni(OH)_2 electrode exhibited the maximum specific capacitance of 1256 F/g at a current density of 200 mA/g in 1 M KOH_((aq)). Ni(OH)_2 electrodes exhibited the pseudocapacitive behavior due to the presence of redox reaction. It also exhibited long-term cyclic stability of 85% after 2000 cycles, suggesting that the nanostructured Ni(OH)_2 electrode will play a promising role for high performance supercapacitor application.     

Room temperature H2S micro-sensors with anti-humidity properties fabricated from NiO-In2O3 composite nanofibers

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.     

花状Ni(OH)2微球的制备及其对尿酸的快速检测

采用微波辅助水热法制备了均匀分级的氢氧化镍(Ni(OH)₂)微球,通过X射线衍射(XRD)仪、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对Ni(OH)₂的组成和形貌进行了表征. Ni(OH)₂微球的平均直径约1.6 μm,复杂的花状结构使其具有较大的比表面积.将微球制备成Ni(OH)₂修饰的玻碳电极,并将其用于0.1 mol/L NaOH溶液中尿酸(UA)的检测,该电极具有良好的电催化活性.这种传感器表现出较宽的线性范围(0.1~1.5 mmol/L)和高灵敏度(475.71 μA ·L/(mmol ·cm2)),且有较低的检出限(1.8 μmol/L).利用电化学测试对内源性干扰物进行检验,发现Ni(OH)₂微球修饰电极对UA的选择性较好.结果表明:Ni(OH)₂微球在研发无酶尿酸传感器方面具有重要的应用潜力.     

钼掺杂氧化铁基纳米材料的合成及气敏性能研究

利用柠檬酸溶胶-凝胶法合成掺杂钼的Fe2O3复合氧化物对H2S等还原性气体有很高的灵敏度,并利用XRD对产品的物相进行了分析;用TEM或SEM对粉体晶粒的粒径和形貌进行了观察;将产物粉体制成气敏元件,采用静态配气法在气敏测试仪上进行了灵敏度和响应-恢复曲线的测试,研究证明钼铁复合氧化物对H2S气体有很好的气敏特性,其中...     

Synthesis and Electrochemical Properties of Porous α-Co(OH)_2 and Co_3O_4 Microspheres

Both α-Co(OH)_2 and Co_3O_4 porous microspheres have been synthesized by the simple solvothermal process as well as subsequent treatment. The morphologies and structures of the as-synthesized products were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), and X-ray photoelectron spectroscopy(XPS). Both samples have spherical structures consisting of nanosheets, with similar crystallinity. The electrochemical properties of both samples were further investigated. Both samples show excellent electrochemical performances including high specific capacity, good cycling stability and rate capability. All results show that these microspheres exhibit potential applications in energy storage field.     

WO3基H2S气体传感器的研究

介绍了电子束蒸发WO