Co系钙钛矿化合物的CO催化氧化与气敏性能

考察了La_(1-x)Sr_xCoO_3(X=0,0.2,0.4)系列钙钛矿型化合物对CO氧化的催化性能及气敏性能,发现其催化及气敏性能均很好,Co系钙钛矿在还原气氛中呈高电阻,在氧化气氛中为低电阻,电阻电子跃迁幅值很大达2个数量级,可望作为燃料的空气燃料(A/F)比传质材料,机理分析研究表明,Co系钙钛矿的催化及气敏作用机理为晶格氧反应机理。A位Sr~(2+)含量越多,B位Co离子价态越高,晶格氧活泼性越大,CO催化活性越好与之密切相关的气敏性能也越好。     

粉末溅射SnO2／CeO2薄膜酒敏元件

介绍粉末溅射SnO2/CeO2酒敏薄膜特性的研究和气敏元件及气敏层参数的设计。介绍元件热功耗的规律,反应温度的规律,测试电压对灵敏度的影响的规律。讨论了用相对灵敏度消除湿度影响的设想,以及对低功耗元件,简单气敏元件集成电路研制等问题。     

纳米CuO-SnO2 气敏粉体的制备及气敏特性研究

用So l-Ge l 法制备了纳米级的CuO -SnO₂ 气敏粉体, 所得粉体制作的气敏元件有较好的气敏性能。在不同的加热电压下进行实验研究, 对不用浓度配比制成的气敏元件进行气敏性能测试。通过对所得粉体的表征可知, 用So l-Gel 法制备出的CuO-SnO₂ 气敏粉体是纳米级的, 比表面积大, 活性好, 其最佳热处理温度为650 ℃, 测试结果得出CuO 摩尔分数为4 %的CuO-SnO₂ 气敏元件有较好的灵敏度和较高的选择性, 并且对CO₂ 的灵敏度和选择性比较突出。     

氧化钛锡复合纳米粉的制备及其气敏性

TiO2和SnO2都是n型半导体,广泛应用于检测H2、CO、醇类等气体的气敏传感器的研究中.本文以钛酸丁脂Ti(OC4H9)4和结晶四氯化锡SnCl4.5H2O为原料,采用共沉淀法,制备出氧化钛、氧化锡复合纳米粉.通过XRD、AFM对制备的复合材料进行了表征.以二氧化锡和二氧化钛摩尔比分别为2∶1;4∶1;6∶1;8∶1;10∶1的5种复合纳米粉体为基体材料,制成旁热式气敏传感器;采用静态配气法测试了各元件对乙醇气体的气敏性能;对元件的灵敏度、响应及恢复特性进行了研究;并分析了乙醇浓度、加热温度等对气敏元件气敏性能的影响.结果表明,复合材料由纳米晶粒组成,复合材料中TiO2含量低于12.5%时,钛离子取代锡离子形成固溶体,其气敏性能较高;TiO2含量大于12.5%,TiO2独立形核,形成两相复合纳米粉.复合材料对乙醇的灵敏度随浓度的增加而增大,呈现出比较好的线性关系.在273℃,乙醇体积分数为400×10-6时,n(SnO2)∶n(TiO2)=10∶1的复合粉体制备的气敏元件的灵敏度高达130.7;并且元件具有良好的响应及恢复特性.     

紫光激发对ZnO纳米线氨气气敏性能的影响

分析了ZnO基气体传感器在应用中存在灵敏度低、响应和恢复时间长的问题.以物理热蒸发法制备的ZnO纳米线为气敏基料,制作成旁热式气敏元件.采用紫光(波长为370~395 nm)激发,用静态配气法对浓度为100 mL/m3的氨气进行了气敏性能的测试.ZnO纳米线气敏元件对氨气检测的灵敏度提高了353%,响应时间和恢复时间分别缩短了4 s和1 s.     

不同模板剂对石墨烯/WO3 复合材料结构与性能的研究.

以氧化石墨烯和Na_2WO_4·2H_2O原料,在不同的模板剂条件下,通过水热合成法制备石墨烯/WO_3复合材料,采用扫描电镜和X射线衍射仪对产物的组成及形貌进行表征,将合成的复合材料制备成气敏元件,通过静态配气法对复合材料的气敏性能进行研究。结果表明,在70?C工作温度下,以K_2SO_4为模板制备的石墨烯/WO_3气敏元件对H_2S气体表现出更好的选择性,适用于制备H_2S气体传感器;在工作温度为100?C时,以(NH_4)_2SO_4为模板制备的石墨烯/WO_3气敏元件对NO_2气体具有最大的灵敏度,同时表现出很好的选择性,可以被用来制备NO_2气体传感器。     

STUDY ON THE SENSITIVE CHARACTERISTICS OF TITANIA TO A/F RATIO

By analogue experiment of exhaust gas, thesensitive characteristics of titania to air/fuelratio was investigated. The effects of some impuri-ties on the electric conductivity of TiO_2, thedeviation of (A/F)c from (A/F)s in nonequilibriumgas system and the self-catalytic oxidation of TiO_2were explained respectively. The effects of ca-talyst, porosity and thickness of sensor element onthe response time was also analyzed.     

纳米Co3O4的制备及其臭氧辅助下对乙醇的气敏性能

以CoOCl₂·6H₂O为钴源,NaOH为沉降剂,通过水热法制备出Co₃O₄纳米粉末,并以Co₃O₄纳米粉末为敏感材料制作了旁热式气敏元件。X射线衍射和透射电子显微镜表征显示Co₃O₄纳米粉晶粒平均粒径15.6 nm。气敏测试结果表明元件在80 ℃、臭氧质量浓度为4.280×10^-8 g/mL的条件下,对2.009×10^-7 g/mL乙醇的灵敏度达到29,而空气中时元件对乙醇的灵敏度仅为4,O₃的加入提高了Co₃O₄气敏元件在80 ℃的灵敏度,并将对乙醇气敏的最佳工作温度由100 ℃降低至80 ℃,实现了Co₃O₄在低温下（80 ℃）的气敏性能检测。     

SnO2气敏元件敏感性能的研究

为了探讨具有优良性能的SnO2气敏元件的研制方法,依据半导体晶界气敏理论．以SnO2为基体材料,采用烧结型工艺和溶胶一凝胶方法制备出了气敏器件,并对该元件的气敏特性进行了测试,结果表明,采用溶胶一凝胶方法制备的气敏元件具有较高的灵敏度和低电阻等特点,对氢气响应时间可以达到5s.     

掺镍多孔纳米SnO2材料的制备及其气敏性能

以SnCl4·5H2O为原料,聚乙二醇(PEG-1000)作为分散剂,利用沉淀法制备出SnO2纳米粉体,采用扫描电镜(SEM)和X-射线衍射(XRD)对其形貌和微观结构进行表征.并以其作为基底材料以离子的形式掺杂摩尔比为1%的Ni2+作为气敏材料,制作掺杂和未掺杂两种旁热式气敏元件,测试其对乙醇、甲醇和丙酮的气敏特性.发现在较低的工作温度下两种元件对三种气体都有较高的敏感性,同时Ni离子的掺杂对三种气体的灵敏度有不同的影响,对乙醇表现出很好的选择性.     

碳纳米管/TiO2电极光电催化测定耐兰方法探讨

自合成二氧化钛-碳纳米管（TiO2一CNT）复合催化剂，用Nafion溶液把CNT—TiO2固定到玻碳电极上制成CNT—TiO2／GC修饰电极，以耐兰染料为测定对象，进行光电化学响应研究．结果表明，在pH7．2的磷酸盐缓冲液中，示差脉冲伏安法（DPV）测定，分散兰1于-0．4V（vs Ag／AgCl）处产生良好的阴极还原峰，电极对耐兰染料的吸附过程符合Langmuir吸附，其光电响应值高于碳糊／TiO2电极．高光电响应意味着复合材料制成电极后，对有机染料废水的检测限更低，灵敏度更高。     

管载二氧化钛凝胶镀膜光催化清除乙烯气体

报道了用sol gel方法在玻璃管上制备二氧化钛薄膜对清除乙烯气体的光催化实验,研究了二氧化钛一次镀膜对乙烯浓度随催化反应时间的变化关系。结果发现,二氧化钛镀膜有较好的清除乙烯的效果,当反应进行到46h时乙烯气体的色谱峰完全消失,即乙烯气体已经被完全清除掉,对相同处理条件下的二氧化钛粉体做XRD分析知该条件下的二氧化钛为锐钛矿晶型。     

The Preparation of Porous Activated Slag Granules/TiO_2 Photocatalyst and Its De-NO_x Performance

The porous structure and honeycombed structure of granulated blast furnace slag formed by alkali activation (AGBFS) can be used as a promising photocatalysts substrate for the photocatalytic removal of atmospheric or water pollutants.In this study,photocatalytic activated slag granules were synthesized by loading TiO_2 on AGBFS with immersion method.The physicochemical properties and NO_x removal performance of activated slag granules/TiO_2 photocatalysts were studied by X-ray diffraction (XRD),scanning electron microscope (SEM) and photocatalytic performance test.The effects of slag particle sizes and nano-TiO_2 loading concentrations on photocatalytic efficiencies of NO_x removal were also investigated.It was found that the De-NO_x performance of activated slag granules/TiO_2 photocatalyst increased with the increasing of slag particle size in low TiO_2 loading concentration situation,while increasing the TiO_2 loading concentration would result in the opposite De-NO_x performance as slag size increased.Nevertheless,for the same size activated slag,the photocatalytic efficiency of activated slag granules/TiO_2 photocatalyst gradually improved with the increase of loading concentration of TiO_2.     

Detection of Methanol by a Sensor Based on Rare-earth Doped TiO_2 Nanoparticles

The rare earth doped TiO_(2) was prepared and characterized with Nd,Ho and Y as the doping agents,which have obvious absorption in visible light area.The particle size of the glomeration was about 200-400 nm.TiO_2 sensor performed a significant change in resistance when exposed to methanol vapor.By comparison,the Nd,Ho and Yb doped TiO_2 sensors exhibited a response of 2.22,4.05 and 3.78,and lowered response and recovery times of 91,56 and 67 s,respectively.The Ho doped TiO_2 showed the best methanolsensing properties,which exhibited high selectivity and response to methanol compared with the other tested vapors.In concentration of 0-10 ppm,the sensor exhibited excellent stability for detecting methanol at various concentrations.     

溶胶-凝胶法制备纳米TiO2/SnO2复合微粒的研究

以有机、无机盐为原料，通过加入稳定剂、催化剂，采用溶胶-凝胶法制备TiO2、SnO2、TiO2／SnO2纳米微粒，采用XRD、SEM和XPS等技术对粒子性能进行分析．结果表明：TiO2／SnO2粒子主要由锐钛矿型TiO2和金红石型SnO2组成，与纯TiO2、SnO2相比，TiO2／SnO2微粒的粒度小，分布均匀，不团聚。     

TiO2/SiO2复合气凝胶的制备研究

采用溶胶-凝胶方法制备TiO2/SiO2复合气凝胶,利用低表面积的溶剂进行替代、分级陈化和干燥,形成较为完善的网络结构,使得TiO2/SiO2复合气凝胶能够非超临界制备.所制得的复合气凝胶孔径20~40 nm,比表面积200~400 m2/g,孔体积1~2 cm3/g.     

光催化微O3氧化饮用水中腐殖质研究

研究了以光催化微臭氧氧化为主体的光化学激发氧化技术,以粉末状二氧化钛(TiO2)为催化剂,对水中腐殖酸进行了光催化氧化研究.探讨了微量O3对腐殖酸的氧化作用,结果表明利用光催化微臭氧氧化法能有效地去除水中腐殖酸.同时对UV/O3、UV/TiO2/空气、UV/TiO2/O3、UV/TiO2/微O34种不同工艺处理微污染水中腐殖酸的结果进行了比较,结果表明UV/TiO2/空气工艺对微污染水中腐殖酸的去除率最低,UV/TiO2/微O3工艺经2 h处理去除率可达70%以上,接近光催化臭氧氧化处理结果.     

陶瓷填料与光催化剂对反应器效率的影响

目的了解陶瓷填料与光催化剂对气体放电-光催化反应器净化效率的影响.方法通过理论计算、吸附实验和电容测试等方法对气体放电-光催化反应器所用的A、B两种陶瓷填料以及附着纳米TiO2光催化剂的B类陶瓷填料物理特性进行了分析.结果A类陶瓷的介电常数计算值大于B类陶瓷的计算值;介电常数的实验值为A类陶瓷相似文献   

Degradation of Formaldehyde and Benzene by TiO_2 Photocatalytic Cement Based Materials

A novel photocatalytic cement based material was prepared. The distribution of TiO_2 on the surface of cement was characterized by scanning electron microscope(SEM) and X-ray diffraction(XRD), which showed the relationship of photocatalysis and presence of TiO_2. TiO_2 also had an impact on cement hydration, which was studied by thermal analysis. With 300 W UV illuminations, formaldehyde and benzene were degraded efficiently by the prepared photocatalytic cement based materials. 15wt% TiO_2/cement showed the highest degradation efficiency and capability. The results show that formaldehyde and benzene can be degraded within 4 and 9 hours, respectively. Besides, inorganic ions can induce TiO_2 agglomeration. As a result, the presence of inorganic ions in cement is unfavorable for degradation. The photocatalytic cement based materials were fabricated and the degradation efficiency of formaldehyde was measured on building roof under sunlight illumination. Formaldehyde in glass chamber can be degraded thoroughly within 10 days.