Mesoporous tin oxide nanospheres for a NO_x in air sensor

Mesoporous tin oxide（SnO_2/ with a high surface area of 147.5 m^2/g has been successfully synthesized via self-assembly process, combining the driven forces of water-evaporation and molecular interactions. Scanning electron microscope, X-ray diffraction, transmission electron micrograph, Fourier transform infrared and BrunauerEmmett-Teller were employed to analyze the morphology and crystal structure of the as-synthesized mesoporous materials. As a gas sensor, mesoporous SnO_2 shows impressive performances towards NOx gas with high selectivity and stability as well as ultra high sensitivity about 94.3 to 10 ppm NO_x gas at 300 ℃. The best response time of the sample S-500 is about 3.4 s to 10 ppm NO_x at 450℃.

In situ sulfur-doped mesoporous tungsten oxides for gas sensing toward benzene series

Benzene series as highly toxic gases have inevitably entered human life and produce great threat to human health and ecological environment,and thus it is distinctly meaningful to monitor benzene series with quickly,real-time and efficient technique.Herein,novel sulfur-doped mesoporous WO_(3)materials were synthesized via classical in-situ solvent evaporation induced co-assembly strategy combined with doping engineering,which possessed highly crystallized frameworks,high specific surface area(40.9–63.8 m^(2)/g)and uniform pore size(~18 nm).Benefitting from abundant oxygen vacancy and defects via S-doping,the tailored mesoporous S/m WO_(3)exhibited excellent benzene sensing performance,including high sensitivity(50 ppm vs.48),low detection limit(ca.500 ppb),outstanding selectivity and favorable stability.In addition,the reduction of band gap resulted from S-doping promotes the carrier migration in the sensing materials and the reaction at the gas–solid sensing interfaces.It provides brand-new approach to design sensitive materials with multiple reaction sites.

Toward High Capacity and Stable SnO_(2)Hollow Nanosphere Electrode Materials:A Case Study of Ni-substituted Modification

To develop the urgent requirement for high-rate electrodes in next-generation lithium-ion batteries,SnO_(2)-based negative materials have been spotlighted as potential alternatives.However,the intrinsic problems,such as conspicuous volume variation and unremarkable conductivity,make the rate capability behave badly at a high-current density.Here,to solve these issues,this work demonstrate a new and facile strategy for synergistically enhancing their cyclic stability by combining the advantages of Ni doping and the fabrication of hollow nanosphere.Specifically,the incorporation of Ni^(2+)ions into the tetragonal rutile-type SnO_(2)shellsimproves the charge transfer kinetics effectively,leading to an excellent cycling stability.In addition,the growth of surface grains on the hollow nanospheres are restrained after Ni doping,which also reduces theunexpected polarization of negative electrodes.As a result,the as-prepared Ni doped electrode delivers a remarkable reversible capacity of 712 mAh g^(-1)at 0.1 A g^(-1)and exhibits outstanding capacity of 340 mAh g^(-1)at 1.6 A g^(-1),about 2.58 times higher than that of the pure SnO_(2)hollow sample.

A versatile ligand-assisted cooperative template method to synthesize multi-shelled mesoporous hollow metal hydroxide and oxide nanospheres as catalytic reactors

Nowadays,multi-shelled mesoporous hollow metal oxide nanospheres have drawn a lot of attention due to their large internal space,nanometer scaled shell thickness,high specific surface area and well-defined mesopores,of which unique nanostructure endows metallic oxides with enhanced properties.In this thesis,we have studied and proposed a versatile ligand-assisted cooperative template method to synthesize multi-shelled mesoporous hollow metal hydroxides and oxides nanospheres,in which silica nanospheres act as sacrificial templates and the coordination interaction between metal ions and surfactant can be cooperatively amplified by using chelating ligand(ascorbic acid)as a co-template.The synthesized metal hydroxides and oxides nanospheres possess stable hollow structure,uniform spherical morphology and tunable diameter from 270 to 690 nm.All the multi-shelled mesoporous hollow metal hydroxide and metal oxide nanospheres exhibit high surface areas(up to 640 m^(2)/g).The obtained Au nanoparticles loaded composited nanospheres exhibit excellent reactivity for solvent-free aerobic oxidation of ethylbenzene with high activity(28.2%)and selectivity(87%).

Gadolinium-doped mesoporous tungsten oxides:Rational synthesis,gas sensing performance,and mechanism investigation

As a typical family of volatile toxic compounds,benzene derivatives are massive emission in industrial production and the automobile field,causing serious threat to human and environment.The reliable and convenient detection of low concentration benzene derivatives based on intelligent gas sensor is urgent and of great significance for environmental protection.Herein,through heteroatomic doping engineering,rare-earth gadolinium(Gd)doped mesoporous WO_(3)with uniform mesopores(15.7–18.1 nm),tunable high specific surface area(52–55 m^(2)·g^(−1)),customized crystalline pore walls,was designed and utilized to fabricate highly sensitive gas sensors toward benzene derivatives,such as ethylbenzene.Thanks to the high-density oxygen vacancies(OV)and significantly increased defects(W^(5+))produced by Gd atoms doping into the lattice of WO_(3)octahedron,Gd-doped mesoporous WO_(3)exhibited excellent ethylbenzene sensing performance,including high response(237 vs.50 ppm),rapid response–recovery dynamic(13 s/25 s vs.50 ppm),extremely low theoretical detection limit of 24 ppb.The in-situ diffuse reflectance infrared Fourier transform and gas chromatograph-mass spectrometry results revealed the gas sensing process underwent a catalytic oxidation conversion of ethylbenzene into alcohol species,benzaldehyde,acetophenone,and carboxylate species along with the resistance change of the Gd-doped mesoporous WO_(3)based sensor.Moreover,a portable smart gas sensing module was fabricated and demonstrated for real-time detecting ethylbenzene,which provided new ideas to design heteroatom doped mesoporous materials for intelligent sensors.

聚吡咯/二氧化锡杂化材料的制备及气敏性研究

化学氧化法制备了聚吡咯(PPy),并进行了元素分析、TG-DTA分析、FTIR测试。讨论了氧化剂用量对PPy气敏性的影响。用机械共混法制备了含不同聚吡咯的聚吡咯/二氧化锡杂化材料,研究其低温下对有毒气体NH3、H2S、NO的敏感性。结果表明,相同条件下聚吡咯/二氧化锡杂化材料的气敏性和稳定性均优于聚吡咯、二氧化锡。60℃时,当聚吡咯/二氧化锡杂化材料中聚吡咯的质量分数为5%时,其对体积分数为0.05%的H2S的灵敏度(Vg/Va)达到了104.52,且响应恢复时间短。文章讨论了气体与敏感元件的相互作用机制。这一研究有助于开发低能耗、灵敏度高的气敏元件。

硝酸氧化法氧化锡陶瓷材料的制备、掺杂与气敏性能

采用正交试验法研究了硝酸氧化法ＳｎＯ２陶瓷材料的工艺条件对ＳｎＯ２收率和环境的影响。用Ｘ射线衍射法测得了不同热处理温度下陶瓷材料的晶体结构，并计算了平均晶粒尺寸。研究了晶粒尺寸和贵金属掺杂对ＳｎＯ２气敏性能的影响，得到了ＳｎＯ２气敏陶瓷的优化工艺条件。

氧化锡气敏传感器动态响应特性用于农药残留检测的研究(英文)

本文介绍了氧化锡气敏传感器参杂金属(Sb,Ca,Sr)的制备及检测农药残留检测装置的原理,通过对氧化锡气敏传感器,在动态与静态条件下,检测农药残留的响应特征及影响因素进行了研究,如采用电压、占空比、电压波形(矩形波、正弦波、锯齿波、脉冲波)的变化,比较研究了农药残留检测的动态与静态响应特征,结果表明动态的测量方法比静态方法可以得到更多的信息,用这种动态测量方法检测对硫磷等有机磷类农药残留具有良好效果。

金属硝酸氧化法制备的SnO_2微粉的气敏特性研究

本文研究采用金属锡硝酸氧化法制备的SnO_2微粉的气敏性能,发现该方法制得的SnO_2微粉具有良好的气敏特性,掺杂后做成的气敏元件对可燃气体具有很高的灵敏度,可抵抗高浓度可燃气体的冲击,长期稳定性好。

弱酸性介质中介孔Sn-SiO_2的合成以及形貌控制

采用原位一步合成的方法,成功地在弱酸性水溶液中合成出具有介孔结构的Sn-SiO2材料。小角X-射线衍射(XRD)的结果表明,当合成母液中Sn/Si的摩尔比为0.05时,所得样品具有高度有序的介孔结构;继续增加Sn的掺杂量会使得有序介孔的规整性下降。同时,广角XRD和紫外-可见漫反射谱的结果显示,Sn物种在介孔SiO2中以四配位骨架掺杂和六配位氧化物纳米粒子两种形式存在。扫描电子显微镜(SEM)结果表明,随着Sn掺杂量的变化,样品的形貌会发生明显的改变。