基于紫外吸收光谱技术的混合气体SO2和H2S浓度的实时监测

采用紫外波段吸收光谱检测技术,实现了SO₂和H₂S混合气体各组分浓度的实时监测。在实验中选用氘灯为测试光源,MAYA2000Pro光谱仪用于采集数据。基于光谱的峰谷特性,选择吸收光谱上波长非常接近的两个来推导SO₂气体的浓度公式,该方法可以忽略其他气体散射和吸收的影响。H₂S气体的吸收光谱可以通过减去混合气体中相应的SO₂气体吸收光谱获得。在常温常压下,H₂S气体的浓度可以从H₂S气体的吸收光谱的吸收峰获得。混合气体的测量精度约为1×10^-6(1 ppm)。基于上述方法,实现了混合气体SO₂和H₂S浓度的实时监测。     

五角石墨烯吸附H2S的第一性原理计算

硫化氢作为一种神经毒物和腐蚀性气体污染物,严重威胁人体健康并限制工业的发展.本文采用第一性原理计算的方法,研究了H₂S气体分子在原始五角石墨烯、非金属掺杂及金属掺杂五角石墨烯上的吸附行为.详细计算了H₂S气体分子与五角石墨烯之间的吸附构型、吸附能及电荷转移.结果表明:1)原始五角石墨烯和非金属元素掺杂五角石墨烯与H₂S气体分子间仅为微弱的物理吸附,无法直接用于吸附H₂S气体;2) Co、Ni、Cu及Ti掺杂的五角石墨烯对H₂S气体的吸附作用显著增强.当金属掺杂在sp~2C位置时,掺杂五角石墨烯对H₂S气体的吸附效果较好,此时的吸附均为化学吸附;3) Co、Ni、Cu及Ti掺杂的五角石墨烯均可作为H₂S气体的传感/捕获材料.其中Cu掺杂五角石墨烯吸附H₂S气体的效果最好.本文的研究结果对设计开发基于五角石墨烯的H₂S气体传感/捕获材料提供了理论指导.     

H2对Ar稀释SiH4等离子体CVD制备多晶硅薄膜的影响

以SiH₄，Ar和H₂为反应气体，采用射频等离子体化学气相沉积方法在300℃下制备了低温多晶Si薄膜.实验发现，反应气体中H₂的比例是影响薄膜结晶质量的重要因素，在适量的H₂比例下制备的多晶Si薄膜具有结晶相体积分数高，氢含量低，生长速率快、抗杂质污染等特性. 关键词： 低温多晶Si薄膜 等离子体CVD 4')" href="#">Ar稀释SiH₄ 2比例')" href="#">H₂比例     

低温制备SnO2电子传输层用于钙钛矿太阳能电池

SnO₂具有光稳定性优异、可低温溶液制备等优点被视为电子传输层的优异材料之一,广泛应用于高效稳定的平面异质结钙钛矿太阳能电池.本文在低温(150℃)下采用旋涂工艺制备SnO₂电子传输层,探究了SnO₂前驱体溶液不同浓度(SnO₂质量分数为2.5%—10.0%)下制备的SnO₂电子传输层对钙钛矿太阳能电池性能的影响.通过对SnO₂薄膜进行扫描电子显微镜(SEM)、紫外-可见光(UV-Vis)吸收光谱和透射光谱分析,发现基底的覆盖率、透光率和SnO₂薄膜的带隙随SnO₂前驱液浓度的增加而增大;通过对SnO₂/钙钛矿(MAPbI₃)薄膜进行SEM、UV-Vis、X-射线衍射(XRD)、稳态光致发光(PL)光谱分析,发现SnO₂胶体分散液浓度为7.5%制备的SnO₂层上沉积的MAPbI₃的粒径最大,结晶度最好,具...     

In2O3/SnO2薄膜的制备及光谱反射性能研究

开展了在伪装网基布上镀In₂O₃/SnO₂薄膜的性能研究,系统分析了薄膜厚度对其光谱反射性能的影响;总结了薄膜厚度对In₂O₃/SnO₂薄膜表面形貌、光谱反射辐射性能的影响规律,为In₂O₃/SnO₂薄膜的红外伪装应用奠定了基础理论和实验依据. 关键词： 2O₃/SnO₂薄膜')" href="#">In₂O₃/SnO₂薄膜 红外反射特性 红外发射率 可见光—近红外透过率     

CO2/CO干扰下基于腔衰荡吸收光谱的痕量H2S浓度测量

H₂S作为一种有毒且腐蚀性较强的气体污染物,实现其浓度的准确测量意义重大.实际工业过程中,H₂S测量常受其他排放产物的干扰,本文基于腔衰荡吸收光谱技术(CRDS)通过扫描6336—6339 cm^-1范围内的吸收光谱,实现了H₂S/CO₂/CO三组分物质浓度的同步测量,为实际工业过程中物质干扰下的H₂S浓度测量提供新思路.首先,对不同采样长度下提取衰荡时间的准确性进行分析,发现衰荡信号的采样长度约为衰荡时间的8倍时,衰荡时间提取效果最好;通过不同压力对比实验确定最佳实验压力工况为50 kPa,并将最佳采样长度与压力工况应用于H₂S浓度测量.随后,改变H₂S浓度对CO₂/CO干扰下系统对痕量H₂S浓度的测量效果进行检验,并对不同稀释比例下浓度测量结果的线性度进行分析.最后,对本文CRDS系统的检测限进行分析,通过对4组低浓度H₂S光谱的信噪比进行分析,...     

基于第一性原理计算Mn掺杂MoS2对油中溶解气体的吸附性能

CO、C₂H₂、CH₄是溶解在变压器油中的典型故障特征气体,其种类和浓度能够反映油浸式变压器绝缘故障的不同类型和严重程度,进行油中溶解气体分析是在线检测变压器运行状态的重要方法.基于第一性原理,通过Mn-MoS₂单层对三种气体的吸附能、转移电荷、态密度和形变电荷密度等参数以及解吸性能分析和灵敏度计算,提出了一种基于Mn-MoS₂材料的气敏传感器对油中溶解气体进行分析的方法.结果表明Mn-MoS₂对CH₄是物理吸附,对CO和C₂H₂是化学吸附.对于Mn-MoS₂来说,CH₄在常温下吸附能力差且灵敏度低,CO在不同温度下均有较强的吸附能力,而C₂H₂在常温下吸附稳定,高温下易解吸且响应灵敏度高.因此,Mn掺杂的MoS₂体系可预期作为CO的气体吸附剂和检测C₂H     

ZnO纳米薄膜及其声表面波传感器的制备与特性研究

结合RF磁控溅射和水热合成法制备ZnO纳米结构薄膜,利用XRD及SEM分析ZnO薄膜的晶体结构和形貌、XPS分析薄膜的化学组分。结果表明,在适当的条件下,所制备的ZnO薄膜为具有良好c轴取向的纳米棒状结构,且ZnO纳米棒薄膜表面吸附的氧原子及晶格的氧空位缺陷增多。利用所制备ZnO纳米棒薄膜的上述特性,将其作为气体敏感材料。分别沉积于128°YX-LiNbO₃和36°YX-LiTaO₃基片,研制多层结构的声表面波(Rayleigh波和Love波)氢气传感器,并进行室温条件下氢气的实时传感检测,结果显示所研制的Love波传感器具有更高的灵敏度,性能更优化。      

LaNi5的硫化物中毒及其再生的表面研究

本文概括了氢气中的硫化物(如H₂S,SO₂和CS₂)对LaNi₅的表面中毒和再生。AES,XPS的分析表明,三种硫化物的中毒性质不同:H₂S中毒产生La₂S₃和NiS这样的表面化合物;SO₂和CS₂中毒分别发生化学吸附和物理吸附。此外,从Ni(2P_3/2)谱峰强度变化,表明了在LaNi关键词：     

Nb/SnO2复合薄膜的制备、结构及光电性能

用溶胶-凝胶旋涂法在玻璃基底上制备出Nb/SnO₂复合透明导电薄膜,利用XRD,SEM,紫外—可见分光光度计,四探针电阻仪等测试方法对Nb/SnO₂复合薄膜的结构和物性进行了研究.结果表明: 当Nb含量小于0.99at%时,Nb/SnO₂复合薄膜为较纯的四方金红石结构;复合薄膜中晶粒分布均匀,平均尺寸在5—7 nm.当Nb含量小于0.99at%时,Nb/SnO₂复合薄膜的电阻率先减小后增大,当Nb含量为0.37at%时 关键词： 溶胶-凝胶法 2复合薄膜')" href="#">Nb/SnO₂复合薄膜 结构表征 光电性能     

多孔ZnO微米球的制备及其优异的丙酮敏感特性

以六水合硝酸锌、尿素为原料,以六亚甲基四胺为表面活性剂,利用水热法合成了多孔氧化锌微米球.通过X射线衍射仪、扫描电子显微镜和吸附仪对样品的结构、形貌、比表面积和孔径进行了表征.利用所得多孔微米球氧化锌制备了气敏元件,并对其气敏特性进行了测试.结果表明:在280℃的工作温度下,表面多孔氧化锌微米球气敏元件对50 ppm的丙酮气体的灵敏度为26.8,响应时间和恢复时间分别约为4 s和10 s,并具有良好的选择性.     

Adsorption and decomposition of H2S on the Ge(100) surface

The adsorption and decomposition of H₂S on the Ge(100) surface is investigated. H₂S is a simple sulfur containing molecule that eventually decomposes to yield hydrogen gas and deposits sulfur on the germanium surface. The surface reactions of H₂S are investigated by ultraviolet photoelectron spectroscopy, Auger electron spectroscopy, and temperature programmed desorption. Room temperature exposure of H₂S to Ge(100) results in dissociative adsorption which can be followed easily by ultraviolet photoelectron spectroscopy. Warming the H₂S exposed surface results in some molecular desorption and further decomposition of the adsorbed species. At saturation, 0.25 ML of H₂S decomposes generating 0.5 ML of atomic hydrogen. Above the hydrogen desorption temperature some etching of the germanium surface is observed by sulfur. The etch product, GeS, is subsequently observed in temperature programmed desorption experiments. Exposure of H₂S to the Ge surface at elevated temperatures leads to higher sulfur coverages. A sulfur coverage approaching 0.5 ML can be deposited at the higher exposure temperatures.     

H2S硫化CuInSe2生成CuIn(SxSe1-x)2薄膜的XRD及Raman分析

将CuInSe₂薄膜在H₂S与Ar的混合气体中硫化是制备CuIn(S_xSe_1-x)₂薄膜的一种常用方法。硫化所用到的CuInSe₂薄膜是用溶剂热法生成的CuInSe₂纳米颗粒旋涂而成。不同于其他真空条件下制备CuInSe₂薄膜的方法.溶剂热法的优点是其相对简单的制备工艺和较低廉的成本。对硫化过程进行研究后发现,硫化温度和时间直接影响CuIn(S_xSe_1-x)₂薄膜的质量,诸如薄膜成分、结晶度、均匀性和带隙宽度都可以通过改变这些实验条件来进行控制。     

Yb-In_2O_3纳米管的制备及其对甲醛的优异气敏性能

采用单管静电纺丝的方法成功制备了纯的与Yb掺杂的In_2O_3纳米管(Yb-In_2O_3).利用扫描电子显微镜和X射线衍射对样品的结构和形貌进行了表征,制作了基于纯In_2O_3和Yb-In_2O_3纳米管的气敏元件.研究表明,Yb-In_2O_3纳米管气敏元件在230℃下对100 ppm甲醛的灵敏度为69.8,是纯In_2O_3纳米管气敏元件对同浓度甲醛灵敏度(18.4)的3.8倍,其对100 ppm甲醛的响应恢复时间分别为4 s和84 s.并且,基于Yb-In_2O_3纳米管的气敏元件对100 ppb甲醛的灵敏度达到2.5.此外,该气敏元件还具有出色的选择性及稳定性,具备良好的实际应用前景.     

氧化钨纳米线气敏传感器的制备及其室温NO_2敏感特性

纳米结构的氧化钨有高比表面积和气体吸附能力,在气体传感器领域得到了广泛研究.本文采用磁控溅射金属钨薄膜和两步热氧化工艺在二氧化硅衬底上生长出氧化钨纳米线.通过改变第二步氧化温度,研究退火温度对氧化钨纳米线气敏特性的影响.采用扫描电子显微镜、X射线衍射仪、X射线光电子能谱分析仪和透射射电子显微镜表征材料的微观特性和晶体结构,利用静态配气法测试气敏性能.研究结果表明,经过退火处理后氧化钨纳米线密度略微降低,300℃比400℃退火后的氧化钨结晶性差,对应的表面态含量多,有利于室温气体敏感性.测试NO_2的气敏性能,经过对比得出300℃退火温度下制备的氧化钨纳米线在室温下表现出较很好的气敏响应,对6 ppm(1 ppm=10~(-6))NO_2达到2.5,对检测极限0.5 ppm NO_2响应达1.37.氧化钨纳米线在室温下表现出反常的P型响应,是因为氧化钨纳米线表面被氧气吸附形成反型层,空穴取代电子成为主要载流子所致.     

Effects of surface treatments and annealing on carbon-based molecular sieve membranes for gas separation

A new method in preparing carbon-based molecular sieve (CMS) membranes for gas separation has been proposed. Carbon-based films are deposited on porous Al₂O₃ disks using hexamethyldisiloxane (HMDSO) by remote inductively coupled plasma (ICP) chemical vapor deposition (CVD). After treating the film with ion bombardment and subsequent pyrolysis at a high temperature, carbon-based molecule sieve membranes can be obtained, exhibiting a very high H₂/N₂ selectivity around 100 and an extremely high permeance of H₂ around 1.5 × 10⁻⁶ mol m⁻² s⁻¹ Pa⁻¹ at 298 K. The O₂/N₂ selectivity could reach 5.4 with the O₂ permeance of 2 × 10⁻⁷ mol m⁻² s⁻¹ Pa⁻¹ at 423 K.

During surface treatments, HMDSO ions were found to be more effective than CH₄, Ar, O₂ and N₂ ions to improve the selectivity and permeance. Short and optimized surface treatment periods were required for high efficiency. Without pyrolysis, surface treatments alone greatly reduced the H₂ and N₂ permeances and had no effect on the selectivity. Besides, without any surface treatment, pyrolysis alone greatly increased the H₂ and N₂ permeances, but had no improvement on the selectivity, owing to the creation of large pores by desorption of carbon. A combination of surface treatment and pyrolysis is necessary for simultaneously enhancing the permeance and the selectivity of CMS membranes, very different from the conventional pore-plugging mechanism in typical CVD.     

Synthesis of ternary compound in H-S-Se system at high pressures

The chemical reaction products of elemental sulfur (S), selenium (Se), and molecular hydrogen (H₂) at high pressures and room temperature are probed by Raman spectroscopy. Two known compounds H₂S and H₂Se can be synthesized after laser heating at pressures lower than 1 GPa. Under further compression at room temperature, an H₂S-H₂Se and an H₂S-H₂Se-H₂ van der Waals compounds are synthesized at 4 GPa and 6 GPa, respectively. The later is of guest-host structure and can be identified as (H₂S)_x(H₂Se)_(2-x)H₂. It can be maintained up to 37 GPa at least, and the stability of its H₂Se molecules is extended:the H-Se stretching mode can be detected at least to 36 GPa but disappears at 22 GPa in (H₂Se)₂H₂. The pressure dependence of S-H and Se-H stretching modes of this ternary compound is in line with that of (H₂S)₂H₂ and (H₂Se)₂H₂, respectively. However, its hydrogen subsystem only shows the relevance to (H₂S)₂H₂, indicating that this ternary compound can be viewed as H₂Se-replaced partial H₂S of (H₂S)₂H₂.     

Glycine on Pt(111): a TDS and XPS study

The adsorption and desorption of in situ deposited glycine on Pt(111) were investigated with thermal desorption spectroscopy (TDS) and X-ray photoelectron spectroscopy (XPS). Glycine adsorbs intact on Pt(111) at all coverages at temperatures below 250 K. The collected results suggest that the glycine molecules adsorb predominantly in the zwitterionic state both in the first monolayer and in multilayers. Upon heating, intact molecules start to desorb from multilayers around 325 K. The second (and possibly third) layer(s) are somewhat more strongly bound than the subsequent layers. The multilayer desorption follows zero order kinetics with an activation energy of 0.87 eV molecule⁻¹. From the first saturated monolayer approximately half of the molecules desorbs intact with a desorption peak at 360 K, while the other half dissociates before desorption. Below 0.25 monolayer all molecules dissociate upon heating. The dissociation reactions lead to H₂, CO₂, and H₂O desorption around 375 K and CO desorption around 450 K. This is well below the reported gas phase decomposition temperature of glycine, but well above the thermal desorption temperatures of the individual H₂, CO₂, and H₂O species on Pt(111), i.e. the dissociation is catalyzed by the surface and H₂, CO₂, and H₂O immediately desorb upon dissociation. For temperatures above 500 K the remaining residues of the dissociated molecules undergo a series of reactions leading to desorption of, for example, H₂CN, N₂ and C₂N₂, leaving only carbon left on the surface at 900 K. Comparison with previously reported studies of this system show substantial agreement but also distinct differences.     

钒掺杂W18O49纳米线的室温p型电导与NO2敏感性能

钨氧化物纳米线在高灵敏度低功耗气体传感器中极具应用潜力, 且通过掺杂改性可进一步显著改善其敏感性能. 本文以WCl₆为钨源, NH₄VO₃为掺杂剂, 采用溶剂热法合成了钒掺杂的W₁₈O₄₉纳米线. 利用扫描电镜、透射电镜、X射线衍射、X射线光电子能谱仪表征了纳米线的微结构, 并利用静态气敏性能测试系统评价了掺杂纳米线的NO₂敏感性能. 研究结果表明: 五价钒离子受主掺杂进入氧化钨晶格结构, 抑制了纳米线沿轴向的生长并导致了纳米线束的二次集聚; 室温下, 钒掺杂W₁₈O₄₉纳米线接触NO₂气体后表现出反常的p型响应特性; 随工作温度逐渐升高至约110 ℃时, 发生从p型到n型的电导特性转变; 该掺杂纳米线气敏元件对浓度低至80 ppb (1 ppb=10^-9) 的NO₂气体具有明显的室温敏感响应和良好的响应稳定性. 分析并探讨了钒掺杂W₁₈O₄₉纳米线的高室温敏感特性及其p-n电导转型机理, 认为钒掺杂W₁₈O₄₉纳米线在室温下的良好敏感响应及反常p型导电性与掺杂纳米线表面高密度非稳表面态诱导的低温气体强吸附有关. 关键词： 氧化钨 纳米线 气体传感器 室温灵敏度