微纳米氧化亚铜的合成与表征

利用溶剂热法,通过改变溶剂异丙醇的浓度成功合成氧化亚铜微晶,并对合成的氧化亚铜微晶进行粉末X射线衍射（XRD）分析以确定物相,扫描电镜（SEM）观察产品结晶形态．     

α-Fe_2O_3中空微球的制备及其气敏特性

以Fe(NO_3)_3·9H_2O为铁源,不同氨基酸作为表面活性剂,通过水热法制备α-Fe_2O_3样品,并用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)及X射线衍射(XRD)表征样品的形貌,测试其气敏性能.结果表明:不同表面活性剂所得α-Fe_2O_3样品的形貌不同,分别为实心粒子和中空微球,且中空微球由粒子堆积而成;基于中空微球的气体传感器对乙醇具有良好的敏感特性.     

Comparative investigation of three types of ethanol sensor based on NiO-SnO2 composite nanofibers

NiO-SnO2 composite nanofibers were synthesized via electrospinning techniques and characterized by X-ray diffraction,scanning electron microscopy,transmission electron microscopy,and X-ray photoelectron spectroscopy.Three types of sensor were applied to investigate the sensing properties of these nanofibers.Sensors A were fabricated by mixing the nanofibers with deionized water,and then grinding and coating them on ceramic tubes to form indirect heated gas sensors.Microsensors B(with an area of 600 μm×200 μm) were formed by spinning nanofibers on Si substrates with Pt signal electrodes and Pt heaters.Sensors C were fabricated by spinning nanofibers on plane ceramic substrates(with a large area of 13.4 mm×7 mm) with Ag-Pd signal electrodes only.The operating temperatures of sensors A and B were controlled by adjusting heater currents,and the operating temperatures of sensors C were controlled by adjusting an external temperature control device.Experimental results show that sensors C possess the highest sensing properties,such as high response values(about 42 to 100 μL/L ethanol),quick response/recovery speeds(the response and recovery times were 4 and 7 s,respectively),and excellent consistencies.These phenomena were explained by the retained fiber morphology and suitable sensor area.The presented results can provide some useful information for the design and optimization of one-dimensional nanomaterial-based gas sensors.     

Excellent ethanol sensor based on multiwalled carbon nanotube-doped ZnO

Multiwalled carbon nanotubes(MWNTs)were synthesized through CVD method,and the gas sensitive materials MWNTs/ZnO were obtained by mixing MWNTs and ZnO.The gas sensing properties of the as-prepared materials were investigated.The results show that the gas sensing properties of ZnO sensor are significantly improved by doping MWNTs.The sensitivity,response time and recovery time to 50 ppm ethanol at 260°C are 46,4 and 20 s,respectively.We also examined the selectivity of 0.1 wt%MWNTs-doped ZnO sensors to different gases.The results show that the sensor possesses an excellent selectivity to ethanol.     

溶剂热法制ZnO纳米棒及其气敏性能

以乙酰丙酮锌为原料,采用溶剂热法首次合成了棒状ZnO纳米粉体,并对该材料在不同工作温度下的气敏性能进行了研究。通过XRD、SEM和TEM等测试手段,表征其物相与结构。该粉体为六方晶系的ZnO纳米棒,直径约为30 nm,长度约为100 nm,结晶良好。通过静态配气法发现:采用N型氧化锌纳米棒所制得的元件在270℃下,对体积分数为5×10-4的乙醇有较好的气敏性能,灵敏度为75,响应时间及恢复时间分别为30、60 s,说明制备的ZnO纳米棒是具有潜力的探测乙醇气体的气敏传感器材料。     

球形氧化镍粉末对乙醇的电催化性能的研究

通过水热-热分解法制备球形介孔氧化镍粉末,并采用X射线衍射、扫描电镜、透射电镜和比表面积仪对氧化镍粉末的形貌和结构进行表征;通过循环伏安法、计时电流法和电化学阻抗谱的测试,系统研究该种粉末在碱性介质中对乙醇的电催化氧化活性.结果表明：所得到的氧化镍粉末为球形,比表面积为35 m2·g-1,平均孔径为15.88 nm;该粉末对乙醇具有良好的催化活性,氧化电流随乙醇浓度和扫描速率的增大而增大,在0.60 V电位下保持1000 s,球形多孔氧化镍对乙醇氧化催化的电流衰减率为0.075%,稳定性比较好.循环伏安法、计时电流法和电化学阻抗谱测试表明,球形介孔NiO/玻碳电极( NiO/GCE)对乙醇的催化氧化反应机理为扩散控制.     

Size tuning and oxygen plasma induced pore formation on silica nanoparticles

Silica nanoparticles have been prepared from tetraethylorthosilicate dissolved in ethanol followed by base-catalyzed condensation.Earlier works reported that at least four parameters,namely concentrati...     

Simple point contact WO3 sensor for NO2 sensing and relevant impedance analysis

A simple and new point contact tungsten trioxide (WO₃) sensor, which can be prepared by the oxidation of tungsten filaments via in-situ induction heating, likely detects low concentration (ppm level) environmental pollutants such as NO₂. X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) were applied to characterize the phase and the microstructure of the samples, respectively. It was found that the synthesized WO₃ films exhibited a monoclinic phase and were composed of hierarchical microcrystals and nanocrystals. The point contact WO₃ sensor (W-WO₃-W) showed rectifying characteristics and an ideal sensing performance of about 110°C. A single semicircle in Nyquist plots was recorded by electrochemical impedance spectroscopy (EIS) at a relatively low temperature of 150°C but faded away above 200°C, which revealed that the sensing process was governed by a determining factor, i.e., grain boundaries at the contact site.     

溶剂热法合成不同形貌的NH4Zr23微晶

在低温溶剂热条件下通过调节实验参数控制合成不同形貌的磷酸锆铵微晶.实验表明,向反应体系中添加氟化铵作为矿化剂可降低反应温度,调节反应体系中磷酸的用量可控制产物粒度.采用XRD和SEM对产物的物相、纯度及形貌进行了表征.对制备出的形貌为削角四面体和片层堆积四面体磷酸锆铵微晶的生长机理进行了探讨,晶体的生长趋向于降低表面能.     

NaGdF4：Eu^3＋的水热合成、相变与发光性质

用水热法制备了NaGdF4：Eu3＋（0.5 mol%）发光材料,并研究了退火温度对NaGdF4：Eu3＋的结构和发光性质的影响。X-射线粉末衍射（XRD）结果表明：水热合成得到六方相的NaGdF4,在空气氛的条件下,NaGdF4从六方相到立方相的相转变温度为～650℃.扫描电镜（SEM）的结果显示：具有六方相结构的NaGdF4：Eu3＋发光材料的粒径为200～300nm.荧光光谱（PL）的结果表明：具有六方相结构的NaGdF4：Eu3＋粉末样品的特征发射为Eu3＋5 D0→7F2（615nm）跃迁发射。     

磷酸银的醇辅助水热法制备及其光催化性能

采用醇辅助水热法,在固定醇与水体积比的情况下,加入乙醇、乙二醇、丙三醇成功制备了多形貌Ag_3PO_4光催化剂。使用扫描电子显微镜、X射线衍射仪、紫外-可见漫反射光谱等检测手段对样品的晶体形貌、晶相结构和光学性能进行表征。研究发现,反应体系中加入醇后,晶体的形貌、分散性及光电学性质发生改变,进而影响其光催化性质;可见光下降解Rh B实验显示,加入乙醇后制备的多面体Ag_3PO_4光催化降解能力最强。     

热处理对Mg-8Gd-3Y-0.5Zr合金组织和力学性能的影响

采用光学显微镜、扫描电镜、透射电镜、室温力学测试、硬度测试等方法,研究了不同热处理工艺对Mg-8Gd-3Y-0.5Zr合金显微组织和力学性能的影响.结果表明,均匀化退火能有效消除枝晶偏析、改善材料的组织和力学性能,δ提高30%;挤压可以明显改善合金的强度和塑性,相比铸态,σb提高,48%,σs提高36%,δ达到6.3%;时效可使挤压态合金的强度得到进一步提高,峰时效时,σb、σs分别达到385.6MPa、310.8MPa,但塑性有所降低,δ降低至4.1%.     

基于COOH/SBA-15的谐振式氨气传感器气敏性能研究

针对化工生产过程中易出现的氨气泄露等问题,采用共聚法合成了羧基功能化介孔硅材料(COOH/SBA-15),并将其作为敏感材料设计了一种石英晶体微天平(Quartz Crystal Microbalance,QCM)式氨气传感器.利用扫描电子显微镜、透射电子显微镜、X射线衍射仪、全自动比表面积和孔隙度分析仪、傅里叶变换红外光谱仪等对敏感材料的形貌和结构进行了表征,并系统地研究了基于COOH/SBA-15的QCM传感器的气敏性能.测试结果表明该传感器对氨气(NH3)的检测限可达到10-6(体积分数),所合成的COOH/SBA-15-2样品对体积分数为20×10-6的NH3响应恢复时间分别为5s和7s.同时,该传感器对NH3具有较高的化学选择性和稳定性,具有较高的实用价值.     

分级多孔结构NiO/ZnO复合材料制备及其甲醛气敏性能

以向日葵秸秆为生物模板合成一种新型的分级多孔结构氧化镍掺杂氧化锌纳米复合材料(Bio NiO/ZnO),利用X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)对复合材料的组成和结构进行表征.实验结果表明,合成的Bio NiO/ZnO保存了向日葵秸秆材料的原始分级多孔结构,该结构由大量尺寸和形状一致的六方晶系纤锌矿型结构的氧化镍与立方晶系文石相结构的氧化镍球形颗粒堆积组成.与未掺杂的ZnO材料相比,Bio NiO/ZnO复合材料制作的气敏传感器对甲醛具有增强的气敏性能.在240℃的工作温度下,该气体传感器对10^-4的甲醛的响应为42,响应和恢复时间分别为7 s和6 s.检测的下限为1.48×10^-4,与复合物的氧空位浓度增加和两相间p-n型异质结的存在有关.     

In~(3+)掺杂SnO_2纳米粉体的制备及气敏性能研究

以自制的SnO2和In2O3为原料,通过固相研磨法制得了一系列掺有In3+的SnO2纳米粉体,利用X射线衍射仪、透射电镜等测试手段对材料的结构、形貌进行了测量和表征.将该材料制成气敏元件,采用静态配气法测试了材料的对Cl2,NO2,H2,H2S,乙醇,甲醛等气体的气敏性能.探讨了掺杂量、工作电压对SnO2粉体材料气敏性能的影响.研究发现:其中当掺杂In2O3的质量分数为3%时,元件在加热电压为3.5 V下对体积分数为30×10-6的Cl2的灵敏度达到3036,而对其他气体几乎没有响应或者响应很小,元件具有较好的响应-恢复特性,响应时间和恢复时间分别是3 s和8 s,最后简要讨论了SnO2对的Cl2气敏机理.     

Effect of sintering on the optical properties of SiO2 colloidal crystal multilayers

High-quality SiO2 colloidal crystal multilayers were fabricated from ethanol solutions by the vertical deposition method and the effect of sintering on the optical properties of the samples was investigated. Optical properties,which are determined by the photonic band structure, weres tudied by means of light transmission and reflection measurements. The morphology of the samples was characterized by scanning electron microscopy (SEM). SEM images illustrate the ordered close package of the spherical colloids in planes parallel to the substrate surface. In addition, the sampie is crackless as a result of an appropriate drying rate. It is shown that with the increase of the sintering final temperature, though the depth and the width of the peak of Bragg diffraction of the sample vary vastly, the peak produces few blue shifts. Optical measurement results were compared favorably to the microstructural properties of the colloidal crystal multilayers.     

Electron microscopic analysis of KvAP voltage-dependent K+ channels in an open conformation

Voltage-dependent ion channels serve as field-effect transistors by opening a gate in response to membrane voltage changes. The gate's response to voltage is mediated by voltage sensors, which are arginine-containing structures that must move with respect to the membrane electric field. We have analysed by electron microscopy a voltage-dependent K(+) channel from Aeropyrum pernix (KvAP). Fab fragments were attached to 'voltage sensor paddles' and identified in the electron microscopy map at 10.5 A resolution. The extracellular surface location of the Fab fragments in the map is consistent with the membrane-depolarized, open conformation of the channel in electrophysiological experiments. Comparison of the map with a crystal structure demonstrates that the voltage sensor paddles are 'up' (that is, near the channel's extracellular surface) and situated at the protein-lipid interface. This finding supports the hypothesis that in response to changes in voltage the sensors move at the protein-lipid interface rather than in a gating pore surrounded by protein.     

混合溶剂热法合成Ag／AgBr复合物及其光催化性质

以AgN03,KBr为原料,运用混合溶剂热法合成了Ag／AgBr光催化剂,利用X射线衍射（XRD）、透射电子显微镜（TEM）、扫描电镜（SEM）、电子衍射能谱（EDS）、紫外-可见（UV—Vis）光谱等技术对样品进行了表征。以甲基橙（MO）,甲基蓝（Mb）,罗丹明B（RhB）为目标降解物,考察了该光催化剂在可见光辐射下（λ〉420nm）的光催化性能。并且进行了不同的合成方法、尿素与十二烷基苯磺酸钠（SDBS）的不同用量、乙二醇与乙醇的不同体积比对Ag／AgBr样品光催化性能的影响。结果表明：混合溶剂热法合成样品的光催化活性要高于水热法合成的样品,尿素与SDBS的添加量分别为10mmol和0．2g,乙二醇与乙醇的体积比为3：1时,复合物Ag／AgBr表现出最佳的光催化性能。     

Electrocatalytic oxidation of ethanol and ethylene glycol on bimetallic Ni and Ti nanoparticle-modified indium tin oxide electrode in alkaline solution

Bimetallic Ni and Ti nanoparticle-modified indium tin oxide electrode(Ni–TiNPs/ITO) were prepared by a twostep ion implantation method, and their electrocatalytic activity toward the oxidation of ethanol and glycol was evaluated. The ion-implantation method is simple, low-cost and environmental friendly without the use of any binder. The Ni–TiNPs/ITO electrode were characterized by scanning electron microscopy(SEM), atomic force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS). SEM and AFM showed that the nanoparticles on the Ni–TiNPs/ITO electrode had a small range of dispersion(10–20 nm) and high dispersion. Electrochemical performances were measured by cyclic voltammetry(CV) and chronoamperometrics. The Ni–TiNPs/ITO electrode exhibited much higher electrocatalytic activity and stability for ethanol and ethylene glycol oxidation than NiNPs/ITO.     

Improved ethanol, acetone and H2 sensing performances of micro-sensors based on loose ZnO nanofibers

Both one-dimensional nanostructures and porous nanostructures are benefit to the sensing enhancement of semiconducting functional materials.The present paper shows an effective route to combining the advantages of these two nanostructures for a novel type of ZnO nanomaterials.Basically,a pore-forming material is employed in an electrospinning method,and the products are characterized by X-ray powder diffraction(XRD),energy dispersive X-ray spectroscopy(EDX),and transmission electron microscopy(TEM).The obtained materials are loose ZnO nanofibers,which own both porous and one-dimensional nanostructures.Micro-sensors are fabricated by sputtering and etching techniques,and the as-prepared nanofibers are used as the functional materials in them.The sensors show improved sensing properties both in sensitivity and response-speeds.The sensitivity is enhanced from 4 to 8 and the response time is shortened from 14 to 10 s when the sensors are exposed to 100 μL/L ethanol at 260℃.Similar results are also observed in acetone and H2 sensing tests.These enhancements are based on the one-dimensional and porous nanostructures of the nanofibers.