The preparation and gas sensitivity study of polythiophene/SnO2 composites

Nanocomposites of SnO₂ and polythiophene (PTP) were synthesized by the in situ chemical oxidative polymerization method. These nanocomposites were characterized by FTIR, transmission electron microscope (TEM), X-ray diffraction (XRD) and thermogravimetric and differential thermal analysis (TG–DTA) techniques, which proved the polymerization of thiophene monomer and the strong interaction between polythiophene and SnO₂. The composites were used for gas sensing to methanol (MeOH), ethanol (EtOH), acetone, and NO_x at different working temperature. It was found that PTP/SnO₂ materials with different PTP mass percent (1%, 5%, 10%, 20% and 30%) could detect NO_x with very higher selectivity and sensitivity at much lower working temperature than the reported SnO₂. The PTP/SnO₂ nanocomposites responded to NO_x at concentration as low as 10 ppm. PTP/SnO₂ composite containing 5 mass% PTP showed the highest sensitivity at room temperature. The sensing mechanism of PTP/SnO₂ nanocomposites to NO_x was presumed to be the effects of p–n heterojunction between PTP and SnO₂.     

Ultrasensitive methyl salicylate gas sensing determined by Pd-doped SnO2

Efficient chemical warfare agents (CWAs) detection is required to protect people from the CWAs in war and terrorism. In this work, a Pd-doped SnO₂ nanoparticles-based gas sensor was developed to detect a nerve agent simulant named methyl salicylate. The sensing measurements of methyl salicylate under different Pd doping amounts found that the 0.5 at.% Pd-doped SnO₂ exhibited a significant improvement in the detection of methyl salicylate at the ppb (1 ppb = 10⁻⁹) level, and the response value to 160 ppb methyl salicylate is 0.72 at 250 °C. Compared with the pure SnO₂, the response value is increased by 4.5 times, which could be attributed to the influence of the noble metal Pd on the oxygen state and its catalytic effect. In addition, the 0.5 at.% Pd-doped SnO₂ sensor still has an obvious response to 16 ppb methyl salicylate with a response value of 0.13, indicating the lower detection limit of the sensor.     

Sensitivity enhancement for H2 gas detection using a SnO2–Ag2O–PdOx nanocrystalline system

Thick film H₂ sensors were fabricated using SnO₂ loaded with Ag₂O and PdO_x. The composition that gave highest sensitivity for H₂ was in the wt.% ratio of SnO₂:Ag₂O:PdO_x as 93:5:2. The nano-crystalline powders of SnO₂–Ag₂O–PdO_x composites synthesized by sol–gel method were screen printed on alumina substrates. Fabricated sensors were tested against gases like H₂, CH₄, C₃H₈, C₂H₅OH and SO₂. The composite material was found sensitive against H₂ at the working temperature 125 °C, with minor interference of other gases. H₂ gas as low as 100 ppm can be detected by the present fabricated sensors. It was found that the sensors based on SnO₂–Ag₂O–PdO_x nanocrystalline system exhibited high performance, high selectivity and very short response time to H₂ at ppm level. These characteristics make the sensor to be a promising candidate for detecting low concentrations of H₂.     

SnO2-Fe2O3复合材料应用于碳纳米管集流体对锂离子电池性能的影响

水热合成法制备纳米SnO₂-Fe₂O₃复合材料,以SnO₂-Fe₂O₃为活性物质,多壁碳纳米管（MWCNTs）导电纸代替传统铜箔作为负极集流体制作锂离子电池。采用XRD、SEM进行表征,结果显示,SnO₂-Fe₂O₃均匀嵌入到MWCNTs构建的三维导电网络的空隙中。电化学测试结果表明,SnO₂-Fe₂O₃/MWCNTs导电纸作为负极电极能够显著提高锂离子电池的循坏和倍率性能。在100 mA/g电流密度下循环30次,SnO₂-Fe₂O₃/MWCNTs导电纸电池比容量达到1 088 mAh/g,而在200 mA/g电流密度下循环200次后,SnO₂-Fe₂O₃/MWCNTs导电纸比容量能稳定保持在898 mAh/g,表现出良好的循环性能,逐渐增大充放电电流,电池的比容量有所下降但其库伦效率仍然保持在96%以上,而在高倍率（1 600 mA/g）下进行充放电时,SnO₂-Fe₂O₃/MWCNTs导电纸比容量仍然能够保持在547 mAh/g,之后再将电流密度降到100 mA/g,比容量重新回到1 000 mAh/g,SnO₂-Fe₂O₃/MWCNTs导电纸表现出十分优异的电化学性能。      

Au修饰SnO2复合纳米材料的制备和气敏性能

以氯金酸和乙酰丙酮氯化锡为主要材料,通过一步水热法制备了SnO₂和Au修饰的SnO₂（Au/SnO₂）纳米粒子.使用TEM、EDS、XRD和XPS等手段对样品的形貌、组成及结构进行表征,研究了两种材料对乙醇的气敏性能.结果表明,两种纳米颗粒的尺寸都比较均一,平均直径约为9-12 nm;SnO₂为四方金红石结构,Au为面心立方结构;在Au/SnO₂样品中,Au与SnO₂的重量比为2.6%,Au元素主要以Au⁰的价态存在并含有少量的Au³⁺价态;与纯SnO₂纳米粒子相比,Au修饰可显著提高气敏元件对乙醇响应的灵敏度和选择性。     

SnO2@Ti3C2Tx 负极材料的制备及其应用

通过超声辅助和低温热处理在二维Ti₃C₂T_x 纳米片层间原位生长SnO₂纳米颗粒,制备出纳米结构的SnO₂@Ti₃C₂T_x 复合材料。使用X射线衍射、X射线光电子能谱和高分辨透射电子显微镜等手段对其表征,研究了这种材料的结构和性能。结果表明,SnO₂纳米粒子密集分布在Ti₃C₂T_x 片层表面与片层之间,Ti₃C₂T_x 纳米薄片突出的限制效应和良好的类石墨层状结构抑制了SnO₂纳米粒子的体积膨胀和团聚,加速了锂离子和电子的跃迁。同时,嵌入在片层之间的SnO₂纳米粒子防止纳米片层在锂插入/脱出过程中重新堆积,使Ti₃C₂T_x 基体的纵向结构稳定性提高。SnO₂@Ti₃C₂T_x 复合材料两组分之间的协同效应,使其具有良好的倍率性能与长循环性能。     

SnO2退火温度对钙钛矿太阳能电池性能的影响

电子传输层是钙钛矿太阳能电池的关键部分, 起到阻挡空穴、传输电子和减少电子空穴复合的作用。本研究采用低温溶液法制备SnO₂薄膜作为钙钛矿电池的电子传输层, 研究SnO₂的退火温度对电子传输层微观形貌、物理性能以及钙钛矿太阳能电池性能的影响。结果表明: 当退火温度为60、90、120和240 ℃时, SnO₂薄膜表面存在较多的孔隙; 而退火温度为150、180和210 ℃时, 薄膜表面孔隙较少。在实验温度下, 制备的SnO₂薄膜为四方相, FTO玻璃上涂覆SnO₂薄膜后其透过率要优于空白FTO玻璃的透过率。当SnO₂退火温度为180 ℃时, 薄膜的电子迁移率最高, 钙钛矿电池具有最佳的传输电阻和复合电阻, 所得电池的性能最优, 其光电转换效率为17.28%, 开路电压为1.09 V, 短路电流为20.91 mA/cm², 填充因子为75.91%。     

Porous SnO2 sputtered films with high H2 sensitivity at low operation temperature

Undoped and Pd-doped SnO₂ films were deposited at various substrate temperatures and discharge gas pressures using reactive magnetron sputtering. Structural factors of the films, such as crystallite size, grain size, and film density, were systematically investigated. The main objectives of this study are to clarify the operation temperature dependence of the H₂ sensitivity of these films as well as to clarify the dominant structural factor in the determination of the sensitivity. The operation temperature at which the sensitivity defined by (R_a−R_g)/R_g, where R_a and R_g are the resistances before and after exposure to H₂, showed a maximum decreased with decreasing film density. The highest sensitivity of 4470 was obtained for a Pd-doped film with the lowest density of 3.1 g/cm³ at 100 °C. It was found that the sensitivity correlated with film density rather than with crystallite size and grain size. The high sensitivity of a Pd-doped porous film at a low temperature was discussed in relation to the Schottky-barrier-limited transport as well as the chemical and electronic effects of Pd.     

Facile synthesis of Ni-doped SnO2 nanorods and their high gas sensitivity to isopropanol

In this work, pure SnO₂ and Ni-doped SnO₂ nanorods were synthesized through a one-step template-free hydrothermal method and then used to detect isopropanol. Sensors fabricated with the Ni-doped SnO₂ nanocomposites showed the best gas sensing performance when the Ni doping amount was 1.5 mol.%. The response reached 250 at 225 °C, which was approximately 8.3 times higher than that of the pure SnO₂ nanorods. The limit of detection for isopropanol was as low as 10 ppb at the optimum working temperature. In addition, it also displayed good selectivity and excellent reproducibility. It is believed that the enhanced isopropanol sensing behavior benefit from the increased oxygen defects and larger specific surface area by Ni doping.     

SnO2修饰石墨毡电极的制备及其性能表征

采用H₂O₂对石墨毡（GF）进行预处理,然后在其表面电沉积Sn,最后在120℃烘箱氧化24 h制备出SnO₂修饰的石墨毡电极。通过扫描电镜（SEM）对SnO₂修饰前后的石墨毡表面形貌进行表征,采用循环伏安法研究了SnO₂修饰后石墨毡电极的电化学性能。结果表明：SnO₂能够均匀地包覆在石墨毡表面;SnO₂修饰石墨毡后V⁴⁺/V⁵⁺电对的氧化峰的峰电流由0.0538 A增加到0.0708 A,与未处理石墨毡相比增加了31.5%,反应峰出峰持续时间提高,说明SnO₂对V⁴⁺/V⁵⁺电对电极过程具有一定的催化作用。析氧电位由1.382 V增加到了1.517 V,使电极在VOSO₄溶液中的电化学窗口变宽。     

Comparison of the electrochemical behavior of CeO2–SnO2 and CeO2–TiO2 electrodes produced by the Pechini method

CeO₂–SnO₂ and CeO₂–TiO₂ thin films were prepared by the Pechini method and their characteristics were compared, using a fractional factorial design to quantify the effect of five preparation variables. It was observed that CeO₂–SnO₂ electrodes show a greater electrochemical response than the CeO₂–TiO₂ films. The best intercalation charge densities were 18.11 and 9.91 mC/cm² for CeO₂–SnO₂ and CeO₂–TiO₂, respectively. Both films were optically inactive with transparencies, in most cases, higher than 90%.     

SnO_2/C复合材料的制备及NO_x气敏研究

为制备在室温条件下对NOx的检测具有低检测线、响应迅速、灵敏度高的材料,通过高压静电纺丝法制备了多孔SnO2/C复合材料,采用TEM、SEM、XRD等手段研究了复合材料形貌及结构.研究表明：SnO2/C复合材料表面存在丰富的微孔、介孔和大孔,且以10 nm左右的介孔居多.室温下（16～18℃）对SnO2/C复合材料NO...     

SnO2/NiO复合半导体纳米纤维的制备及气敏性能研究

采用静电纺丝技术结合化学沉淀法和高温煅烧处理, 制备了具有不同Sn含量的SnO₂/NiO复合半导体纳米纤维。采用扫描电子显微镜(SEM), X射线衍射仪(XRD)和能量色散X射线光谱仪(EDS)对样品的形貌, 结构以及各元素含量进行表征。以乙醇为目标气体, 探究SnO₂/NiO纳米纤维的气体传感性质, 以及Sn含量对复合纳米纤维气敏性能的影响。研究结果表明, SnO₂/NiO复合纳米纤维具有三维网状结构, SnO₂复合对NiO纳米纤维的气敏性能具有明显的增强作用。随着SnO₂含量的增加, 复合纤维对乙醇气体的响应灵敏度增强, 其中响应最高的复合纳米纤维在最佳工作温度160 ℃条件下对体积分数为100×10^-6乙醇气体的响应灵敏度为13.4, 是NiO纳米纤维最大响应灵敏度的8.38倍。与市面常见的乙醇气体传感器MQ-3相比, SnO₂/NiO复合纳米纤维的最佳工作温度更低, 响应灵敏度更高, 具有一定的实际应用价值。     

一维Pt/SnO2纳米纤维的制备及NOx气敏性研究

为了制备出室温条件下对NO_x气体具有更高灵敏度和更快响应的传感器纳米材料并研究其气敏性能, 本研究通过高压静电纺丝法制备出一维Pt/SnO₂中空纳米纤维。采用XRD、SEM、TEM等表征手段对其结构和形貌进行研究, 同时进行了NO_x的气敏性能测试并予以探讨。研究结果表明: Pt/SnO₂纳米材料是一维中空管状及类似管状结构; 当Pt掺杂量为0.3wt%、NO_x浓度为9.7×10^-5 (V/V)时, NOx响应最快为11.33 s, 灵敏度最高可达109.6%; 当Pt掺杂量为0.5wt%时, 对NO_x检测限最低浓度可达2.91×10^-6 (V/V)。     

二氧化钛/锑掺杂二氧化锡/还原氧化石墨烯复合材料的制备及其光阴极保护性能研究

通过原位生长制备了锑掺杂二氧化锡/还原氧化石墨烯(Sb-SnO₂/RGO)复合材料,再通过水热法生长TiO₂制备了TiO₂/Sb-SnO₂/RGO复合材料。采用X射线衍射、扫描电镜、紫外-可见光、荧光光谱和光电化学等技术对材料的晶体结构、形貌、光吸收特性和电子复合情况进行了表征。结果表明:TiO₂与Sb-SnO₂形成了异质结构,扩大了复合材料的光响应范围,RGO的引入增强了复合材料在可见光区的响应,并提高了电子迁移速率。与TiO₂相比,TiO₂/Sb-SnO₂/RGO复合材料具有更佳的光阴极保护性能。     

Preparation of nanocrystalline SnO2 thin film coated Al2O3 ultrafine particles by fluidized chemical vapor deposition

Fluidized chemical vapor deposition (FCVD) technology was developed for coating SnO₂ thin film on Al₂O₃ ultrafine particles. TEM and HREM analysis found that SnO₂ films with different structures were deposited by controlling the coating temperature, reactant concentration, etc. Nanocrystalline SnO₂ film was coated at 573.15 K by gas phase reaction of SnCl₄ with H₂O. EPMA and EDS studies indicated that the distribution of SnO₂ inner and outer of the agglomerates was uniform. Nucleation and film deposition were coexisted mechanism during the FCVD coating process. The fraction of SnO₂ in the composite particles increased with increasing coating temperature, SnCl₄ concentration, and coating time. The mass fraction of SnO₂ in the composite particles increased strongly with the ratio of P_H2O and P_SnCl4 at low mole ratio of H₂O with SnCl₄, but increased little under the conditions of excess H₂O with respect to SnCl₄.     

二组元（RuO2-TiO2）及三组元（RuO2-SnO2-TiO2）Ti阳极涂层的微观组织对其电化学性能的影响

通过热分解法制备了二组元（RuO₂-TiO₂）和三组元（RuO₂-SnO₂-TiO₂）Ti阳极涂层,并通过SEM、XRD以及电化学工作站对其结构及性能进行测试。结果表明：在烘干温度130 ℃,热氧化温度500 ℃,烧结时间15 min,退火时间1 h的条件下,所制备的三组元（RuO₂-SnO₂-TiO₂）Ti阳极涂层性能较为优异,析氯电位为1.128 V,析氧电位为1.674 V。在二组元（RuO₂-TiO₂）涂层中加入Sn组元,可以减少贵金属Ru的使用量,降低钛阳极涂层的成本;而且所形成的SnO₂可提高涂层表面的电催化活性,降低电极的析氯电位、析氧电位,延长电极的工作寿命。     

SiO2/聚苯乙烯疏水复合微球的一步法合成和性能

提出了以苯乙烯、二乙烯基苯和γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)为单体，通过伴随着溶胶-凝胶反应的悬浮聚合法一步制备表面构筑有SiO₂粗糙结构的交联聚苯乙烯微球(SiO₂/聚苯乙烯疏水复合微球)。研究了油相组成、KH570用量和溶胶-凝胶反应条件对SiO₂/聚苯乙烯疏水复合微球强度和疏水性能的影响。结果表明，当弃除油相中的溶剂甲苯，在50℃的恒温反应阶段采用氨水调控体系pH值为10~11时可以获得兼具持久疏水性能、高强度和超低密度的SiO₂/聚苯乙烯疏水复合微球。SiO₂/聚苯乙烯疏水复合微球的表观密度约0.9917 g?cm?3，69 MPa的闭合压力下破碎率低至2.53%，表面静态水接触角高达140.7°，耐热性能优异(玻璃化转变和分解温度分别高达160℃和390℃)。尤其是，在涠州X油田A5井的螯合酸HD和FA中持续回流30天的过程中，SiO₂/聚苯乙烯疏水复合微球表面的接触角变化仍分别保持在±10%和±7%以内。SiO₂/聚苯乙烯疏水复合微球具备作为深部储层开采用支撑剂的极大潜力，也可用作封隔体控水工艺中的充填材料。      

Influence of the common varistor dopants (CoO, Cr2O3 and Nb2O5) on the structural properties of SnO2 ceramics

The influence of dopants commonly used in SnO₂ varistor ceramics, such as CoO, Cr₂O₃ or Nb₂O₅, on the structural properties of SnO₂ was investigated. Several SnO₂-based ceramics containing only one of the dopants were prepared and characterized. Spectroscopic investigations [visible, near infrared (IR) and IR region] were performed to obtain information about dopants valence states inside the ceramics, as well as about their influence on electronic structure of the material. Structural properties were investigated by X-ray diffraction analysis and mechanisms of dopant incorporation were proposed. Obtained results were confirmed with results of the electrical measurements. Microstructural changes in doped ceramics were investigated by scanning electron microscopy (SEM) analysis that showed great differences in densities, grain size, and morphology of the SnO₂ ceramics depending on type of dopants and their distribution.     

FeVO4/Cu3(BTC)2(H2O)3异质结制备及光催化性能

以Cu片和1, 3, 5-苯三甲酸为原料,电化学法制备经典Cu-MOF材料Cu₃(BTC)₂(H₂O)₃,即HKUST-1,作为基底金属有机框架材料(MOFs),采用室温沉积法制备FeVO₄/HKUST-1异质结复合材料,通过XRD、SEM、BET、UV-Vis DRS等对其晶体结构、形貌、比表面积、光吸收性能等进行了表征。结果表明:FeVO₄与HKUST-1复合形成异质结后,有利于光生电子-空穴的产生和转移,对目标染料污染物罗丹明B(RhB)的降解性能显著增强。可见光照射120 min后,异质结体系中RhB的降解率可达93%,而单一FeVO₄或HKUST-1体系中仅为12%和5%。此外,对材料的组成比例进行了优化,当FeVO₄与HKUST-1摩尔比为1∶1时,制备的FeVO₄/HKUST-1复合材料具有最佳的光催化性能。进一步,考察了其循环使用的稳定性,循环5次后对RhB的降解效率仍保持在90%以上,稳定性良好。