SnO2中空微球的制备与气敏性能

在不加任何表面活性剂情况下,采用磺化的聚苯乙烯（PS）微球为模板,二水结晶二氯化锡（SnCl₂·2H₂O）为锡源,成功制得SnO₂中空微球。利用X射线衍射仪（XRD）、扫描电镜（SEM）、高分辨透射电镜（HRTEM）和氮气吸附脱附仪（BET）对材料的结构和形貌进行了表征,研究并讨论了温度、乙醇浓度等因素对SnO₂纳米颗粒及SnO₂中空微球气敏性能的影响。结果显示,SnO₂中空微球的比表面积为48.49m²/g,比SnO₂纳米颗粒的比表面积（21.94m²/g）提升了1.21倍。比表面积增加有助于SnO₂材料表面吸附更多被测气体以提升表面化学反应,进而提升气敏性能。在260℃下,SnO₂中空微球对200μL/L乙醇的灵敏度为66.26,与SnO₂纳米颗粒相比（51.34）,气敏性能提高了0.29倍。     

Solution blow spinning: A new method to produce micro‐ and nanofibers from polymer solutions

A solution blow spinning technique was developed using elements of both electrospinning and melt blowing technologies as an alternative method for making non‐woven webs of micro‐ and nanofibers with diameters comparable with those made by the electrospinning process with the advantage of having a fiber production rate (measured by the polymer injection rate) several times higher. The diameters of fibers produced ranged from 40 nm for poly(lactic acid) to several micrometers for poly(methyl methacrylate). This solution blow spinning method uses a syringe pump to deliver a polymer solution to an apparatus consisting of concentric nozzles whereby the polymer solution is pumped through the inner nozzle while a constant, high velocity gas flow is sustained through the outer nozzle. Analysis of the process showed that pressure difference and shearing at the gas/solution interface jettisoned multiple strands of polymer solution towards a collector. During flight, the solvent component of the strands rapidly evaporates forming a web of micro and nanofibers. The effect of injection rate, gas flow pressure, polymer concentration, working distance, and protrusion distance of the inner nozzle was investigated. Polymer type and concentration had a greater effect on fiber diameter than the other parameters tested. Injection rate, gas flow pressure, and working distance affected fiber production rate and/or fiber morphology. Fibers were easily formed into yarns of micro‐ and nanofibers or non‐woven films that could be applied directly onto biological tissue or collected in sheets on a rotating drum. Indeed, virtually any type of target could be used for fiber collection. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

SnO2/ZnO复合中空纤维材料的制备及其光催化性能

采用天然棉花为模板制备了具有高光催化活性的SnO2/ZnO复合中空纤维光催化材料;利用X-射线衍射(XRD)、扫描电子显微镜(SEM)技术对其相结构和形貌进行了表征;以亚甲基蓝(MB)的脱色降解为模型反应,考察了Sn4+和Zn2+物质的量比为0.1∶1时煅烧温度对其催化性能的影响。实验结果表明:制备的样品为复制了棉花纤维模板形貌、具有中空结构的SnO2和ZnO半导体复合材料(SnO2/ZnO);煅烧温度对材料SnO2/ZnO的结晶度、晶粒大小﹑表面微结构和催化性能等有显著影响;650℃左右所得样品在太阳光下的催化活性最好,1 h可使MB溶液的脱色降解率达100%;该材料易于离心分离,具有良好的催化活性和重复使用性能。     

Effect of heat treatment on surface structure and gas sensing of electrospun ZnO-SnO2 composite nanofibers

ZnO-SnO₂ composite nanofibers with a constant Zn/Sn ratio of 0.4 have been electrospun and calcined at 650°C in ambient air, followed then by heat treatment at 350°C in either air, 5% H₂-95% N₂, or 15 ppm H₂S-air atmosphere for comparison of gas-sensing behaviors. The nanofibers being heat-treated in the H₂S-air atmosphere display a sensing response more than 25 times than the as-calcined counterpart, that is, the sensing response increases from 20 to 514 against a model NO₂ gas of 10 ppm concentration at a working temperature of 180°C. This appears to be attributable to the formation of sulfate on the nanofiber surface, which resulted in an enriched oxygen vacancy and chemisorbed oxygen near the surface for facilitating the redox reaction toward NO₂ gas molecules. The facile heat treatment in the presence of dilute H₂S concentration may have opened up an alternative route for enhancing the surface-sensitive gas-sensor activity.     

Au‐nanoparticle‐decorated SnO2 nanorod sensor with enhanced xylene‐sensing performance

In this work, pure and Au‐nanoparticle‐decorated SnO₂ nanorods were prepared via a one‐step hydrothermal method combined with a facile deposition process, and then characterized by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, high‐resolution transmission electron microscopy, and X‐ray photoelectron spectroscopy. The xylene‐sensing performance of the nanorods was also investigated. The results show that Au nanoparticles with an average diameter of 4‐6 nm were immobilized on the surface of rutile SnO₂ nanorods. As the amount of Au increased, the surface‐adsorbed oxygen species gradually increased. The 12 mol% Au‐SnO₂ nanorods exhibited the highest response to 50 ppm xylene, a lower operating temperature (279 to 255°C), favorable selectivity, and fast response‐recovery speed (3 and 4 seconds, respectively). These properties made the fabricated nanorods good candidates for xylene detection. The possible mechanism for the enhanced xylene‐sensing performance is discussed.     

ZnO负载SnO2复合材料的制备及其气敏性能

以五水四氯化锡（SnCl₄·5H₂O）和乙酸锌[Zn （AC）₂·2H₂O]为原料,氢氧化钠（NaOH）为沉淀剂,采用简单的水热法,使二氧化锡（SnO₂）纳米颗粒锚定在蚕蛹状氧化锌（ZnO）表面,一步成功合成了二氧化锡/氧化锌（SnO₂/ZnO）复合材料。采用X射线衍射仪（XRD）、透射电镜（TEM）、高分辨透射电镜（HRTEM）和氮气吸附脱附仪（BET）对材料的结构和形貌进行了表征,研究并讨论了温度、乙醇浓度等因素对SnO₂、ZnO及SnO₂/ZnO复合材料气敏性能的影响。结果表明,所得样品为SnO₂纳米颗粒与蚕蛹状ZnO的复合物,SnO₂纳米颗粒较均匀地负载在ZnO表面。SnO₂/ZnO复合材料气敏元件在最佳工作温度为240℃时,对200μL/L乙醇的灵敏度达到39.68,与SnO₂（24.53）及ZnO （17.8）相比,气敏性能得到了很大的提高。     

Visible light active heterostructured photocatalyst system based on CuO plate-like particles and SnO2 nanofibers

In this study, CuO–SnO₂ p-n type heterostructures were produced and tested for the degradation of methylene blue and 4-nitrophenol under visible light irradiation. CuO particles were produced in plate-like morphology using hydrothermal synthesis. SnO₂ nanofibers were obtained by electrospinning. Structural, morphological, optical and semiconducting property characterization of heterostructured CuO–SnO₂ and individual phases were performed. The photocatalytic activity was found to change depending on the amount of CuO particles in heterostructured samples. Among others, the sample with 0.35 wt.% CuO–SnO₂ showed the highest photocatalytic efficiency with a degradation rate constant ~2 h⁻¹. Active specie scavenger tests revealed that the decomposition reaction occurs through direct oxidation mechanism by the holes in the valence band of SnO₂ in pure samples whereas in CuO–SnO₂ samples and radicals also form and involve in the reactions. Further, the photocatalytic degradation mechanism was revealed using relative band potentials and p-n junctions of the heterostructured photocatalyst.     

喷雾燃烧制备SnO2纳米棒及其气敏性能

采用喷雾燃烧法制备SnO2纳米棒,对其形貌和结构进行了表征. 所制SnO2纳米棒长200~350 nm,直径30~50 nm,沿(001)方向生长. 考察了Fe掺杂量和Sn4+浓度对SnO2纳米棒形貌的影响,分析了其生长机理. 高温快速反应使Fe3+进入SnO2晶格,促使其沿(001)方向取向生长. 对乙醇等有机气体的气敏性能测试结果表明,棒状SnO2比颗粒状的具有更优的气敏性能,在100′10-6(j)乙醇浓度下,棒状SnO2的灵敏度为12,反应和恢复时间分别为9.5和6 s.     

正八面体锡酸锌的水热合成

用醋酸锌和亚锡酸钠作为原料,锌锡物质的量比为2∶1,反应体系中有矿化剂氢氧化钠存在,用水热合成方法,在180~220 ℃水热反应10~48 h,成功制备出正八面体纯锡酸锌晶体。用X射线衍射（XRD）、扫描电镜 （SEM）对产物进行了表征。研究了介质的酸碱性、原料配比、反应温度、反应时间等因素对产物合成的影响。     

乙醇在SnO2掺杂的TiO2-Pt复合纳米催化剂上的电催化氧化

通过溶胶凝胶和电沉积法制备了SnO₂掺杂的钛基纳米TiO₂-Pt（nano-TiO₂-Pt）复合纳米催化剂。XRD和SEM的研究结果表明,SnO₂的掺杂改变了TiO₂的结构。通过对它们的电化学性质的比较发现,SnO₂的掺杂使nano-TiO₂-Pt复合纳米催化剂的电化学活性表面积增加,常温常压下对乙醇的电化学氧化电位负移,氧化能力明显提高。     

Preparation, Characterization and Photocatalytic Activities of F-doped TiO2 Nanotubes

F-doped TiO₂ nanotubes were prepared by impregnation method. The prepared catalysts were characterized by XRD, TEM, and XPS. The photocatalytic activity of F-doped TiO₂ nanotubes was evaluated through the photodegradation of aqueous methyl orange. The experiments demonstrated that the F-doped TiO₂ nanotubes calcined at 300 °C possessed the best photocatalytic activity. Compared with pure TiO₂ nanotubes, the doping with F⁻ significantly enhanced the photocatalytic efficiency. The high photocatalytic activity was ascribed to several beneficial effects produced by F-doping: creation of oxygen vacancies, presence of Ti³⁺, and so on. An erratum to this article can be found at     

二氧化铈掺杂中空碳纳米纤维的制备及电化学性能

以葡萄糖为碳源,硝酸铈为铈源,去离子水做溶剂合成前体,使用实验室自制阳极氧化铝模板（anodized aluminum oxide,AAO）作为硬模板,采用真空压力诱导技术将前体注入到AAO的纳米孔道内,热分解合成二氧化铈纳米粒子（CeO₂-NPs）掺杂的中空碳纳米纤维（CeO₂/HCFs）。使用拉曼光谱、电感耦合等离子体质谱（ICP-MS）、透射电镜（TEM）、X射线衍射仪（XRD）、X射线光电子能谱（XPS）对样品进行表征,结果表明,CeO₂/HCFs具有平均直径约为200nm的中空管状结构,具有较好的碳化程度,CeO₂-NPs均匀分布在HCFs中,其晶型为面心立方晶系。通过循环伏安法（CV）与安倍电流-时间法（I-t曲线）技术,研究了支持电解质的pH对检测结果的影响以及CeO₂/HCFs对抗坏血酸的电化学催化性能,实验结果表明支持电解质在pH=4.18时具有最稳定的检测电流,CeO₂/HCFs对抗坏血酸有较高的电化学活性,修饰电极的灵敏度为505.4μA/(cm²·mmol),检出限为0.55μmol/L,线性范围为2.5~8.4mmol/L,具有良好的选择性、稳定性和重现性。该方法快捷、灵敏、稳定、操作简便,具有较大的应用潜力。     

Template-free synthesis of Cu2O hollow nanospheres and their conversion into Cu hollow nanospheres

In this paper, Cu₂O hollow nanospheres were first generated through a template free process, and then Cu hollow nanospheres were prepared using Cu₂O hollow nanospheres as precursor and H₂ as reductant. Phase identification and morphology observation of the products were carried out by X-ray diffraction(XRD), Transmission electron microscopy (TEM) and Field scanning electron microscopy (FSEM). The results show that Cu₂O nanospheres generated at reflux are porous and hollow both in absolute alcohol and tert-butyl alcohol. It is feasible to fabricate well-dispersed Cu hollow nanospheres from Cu₂O hollow nanospheres at 170 °C. Moreover, a remarkable blue shift effect was found in the ultraviolet-visible light (UV-visible) absorption spectra for both Cu₂O and Cu hollow nanospheres.     

固体酸SO4^2-/SnO2催化合成DOP的研究

采用自制的固体酸SO4^2-/SnO2为催化剂合成DOP，分别考察了催化剂用量、醇酐比、反应时间等对合成DOP的影响。实验表明，在DOP的合成中最佳的合成条件是：采用14g的SO4^2-/SnO2催化剂／mol（苯酐），醇酐比为2.35：1，反应时间为3．5h，其酯化率可达91％以上。SO4^2-/SnO2作为该反应的催化剂具有催化活性高、寿命长、可多次重复使用、产物易纯化分离、且产品色泽浅等优点，可望代替传统浓硫酸作催化剂应用于DOP的合成。     

Semi shield driven p-n heterostructures and their role in enhancing the room temperature ethanol gas sensing performance of NiO/SnO2 nanocomposites

The demand for the development of gas sensors operable at room temperature is increasing due to the uncountable drawbacks of high temperature gas sensors. This contribution describes the fabrication of room temperature ethanol sensor. The synthesis of NiO semi shielded SnO₂ (NiO/SnO₂) nanocomposites (NCs) was done via a simple two-step process, started with co-precipitation technique and then followed by sol-gel method. High resolution electron microscope (HRTEM) results indicated the semi shielding of NiO on SnO₂ nanoparticles (NPs). Surface morphological studies of the fabricated sensors show the porous nature of the samples which further helps in enhanced sensing response. X-ray photoelectron spectroscope (XPS) results of NiO/SnO₂ NCs revealed the valence states of Ni (+2) and Sn (+4). Excellent gas sensing response of the NiO/SnO₂ sensor towards ethanol at room temperature was observed from the gas sensing studies. The response of NiO/SnO₂ (∼140) was nearly 9 times higher than SnO₂ sensor (∼15) and nearly 11 times higher than NiO sensor (12.98) towards 100 ppm ethanol at room temperature. The observed response and recovery times of NiO/SnO₂ were 23 s and 13 s respectively. The p-n heterostructure formed between p-NiO and n-SnO₂, and high chemical sensitization and catalytic activity of the NiO are the main contributors for the excellent sensing performance of NiO/SnO₂ sensor.     

纳米SnO2微粒的制备及其表征

以SnCl4.5H2O为原料,用水热合成法制备粒度均匀的纳米SnO2微粒。研究了反应物浓度、反应时间、反应温度等因素对SnO2微粒尺寸的影响。用DSC研究SnO2微粒的热性能,用激光光散射仪和透射电镜分析和观察SnO2微粒尺寸的影响。用DSC研究SnO2微粒的热性能,用激光光散射仪和透射电镜分析和观察SnO2微粒的形态和尺寸。     

Facile fabrication of polyaniline/polypyrrole copolymer nanofibers with a rough surface and their electrorheological activities

Hierarchical polyaniline/polypyrrole (PANI/PPy) copolymer nanofiber was prepared via a two‐step method and adopted as dispersing materials for electrorheological (ER) fluids. The first step was used to synthesize PANI nanofibers by a rapid mixing method. Subsequently, the PANI/PPy copolymer nanofibers with a rough surface were obtained using an in situ polymerization method continuously. The morphology of the resultant PANI/PPy copolymer nanofibers can be controlled by varying the amount of Py monomer in the secondary in situ polymerization method. The rough surface of PANI/PPy copolymer nanofibers were confirmed by scanning electron microscopy and transmission electron microscopy. The diameter of PANI/PPy nanofiber is within the range 100–200 nm. The obtained PANI/PPy copolymer particles all exhibit amorphous structure through X‐ray diffraction measurement. We also demonstrated that the hierarchical PANI/PPy copolymer nanofibers exhibited characteristic ER behaviors, which were investigated using a Haake rotational rheometer at various electric field strengths. The ER efficiency e for PANI‐1mLPPy and PANI‐2mLPPy ER fluids at shear rate 0.1 s⁻¹ is 36.6 and 28.5 under electric field strength E = 3 kV/mm, respectively. Low leaking current density is observed even at high electric field strength and wide plateau region appeared, which show a strong ER activity for the PANI/PPy composite nanofibers. The results also indicate that the PANI/PPy composite particles have distinctly enhanced ER effect compared with the pure PANI and PPy particles under electric stimuli. The significantly improved ER property of PANI/PPy‐based ER fluid is ascribed to the enhanced interfacial polarization. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46289.     

二氧化锡纳米薄膜和纳米线制备技术

SnO2是一种重要的金属氧化物材料,在气敏传感器、透明导电薄膜、电池电极等方面应用广泛。按照纳米薄膜、纳米线的顺序,对SnO2纳米材料的制备技术及最新研究进展进行了详细的综述,报道了一种由高温自蔓延合成引发的制备纳米线的新方法——燃烧合成喷射法,并对未来研究方向进行了展望,认为SnO2纳米薄膜仍是今后一段时间内研究的重点,而SnO2纳米线制备方法的改进与创新将成为该领域的研究难点与前沿。     

The role of water in ethanol oxidation over SnO2-supported molybdenum oxides

The role of water in the oxidation of ethanol to acetic acid on Sn–Mo–O catalysts was studied by catalytic test and FTIR spectroscopy of adsorbed species. The reaction showed a typical behavior of series reactions involving oxidation of ethanol to acetaldehyde and of the latter to acetic acid and CO₂. Addition of water to the feed gas decreased the oxidation rate and significantly increased the selectivity to acetic acid, strongly contributing to decreasing the number of secondary products. FTIR analyses showed that water promotes desorption of ethanol and carboxylates, present as bridging and monodentate species. Decreasing catalytic rate values and increasing selectivity to acetic acid in the presence of water follow from site blocking by hydroxyl groups. This revised version was published online in July 2006 with corrections to the Cover Date.     

SnO_2-高岭土负载硫酸镓催化合成己酸己酯

SnC l4.5H2O和高岭土的质量比1∶3,饱和Ga2(SO4)3溶液浸渍4 h,300℃焙烧2 h,制备了以Ga2(SO4)3为活性组分、SnO2-高岭土为载体的负载型酯化催化剂。用于正己酸与正己醇合成己酸己酯酯化反应,考察了催化剂用量、n(正己醇)∶n(正己酸)、反应时间、带水剂种类及用量等因素对酯化率的影响。结果表明,合成己酸己酯的适宜反应条件为:n(正己醇)∶n(正己酸)=1.4,苯15 mL,催化剂用量为反应物总质量的3.0%,反应时间100 min,酯化率为98.8%。该催化剂催化活性高、成本低、制备方法简单,并且易分离回收。