【作者】 史勇；

【导师】 余海湖；

【作者基本信息】 武汉理工大学 ， 光电子及信息材料， 2010， 硕士

【摘要】 氢能是可再生而又洁净的新能源,氢能大规模应用的瓶颈之一是缺乏可靠、廉价的探测氢气泄漏的氢气传感器。研制氢气传感器的关键问题之一是氢气敏感材料的选择及其敏感元件的制备。V2O5薄膜是一种重要的气体敏感材料,但有关V2O5/Pd薄膜氢气敏感性质的研究不多,为此,本文采用磁控溅射法在玻璃基片上和多模光纤端面上制备了不同厚度的V2O5/Pd薄膜,对V2O5/Pd薄膜结构进行了表征,利用紫外-可见光分光光度计原位检测V2O5/Pd薄膜的氢气敏感特性,采用端面反射型光纤传感系统研究了V2O5/Pd薄膜的氢敏特性,分析了V2O5/Pd薄膜对氢气的敏感机理,论文的主要内容和研究结果如下：(1)XRD分析结果表明,磁控溅射法制备的V2O5薄膜及V2O5/Pd薄膜为非晶态。AFM观察表面形貌结果表明,V2O5/Pd薄膜的粗糙度较小；(2)在玻璃衬底上制备了不同厚度的V2O5/Pd薄膜,采用紫外-可见光分光光度计原位测试V2O5薄膜及V2O5/Pd薄膜的氢敏性能。发现V2O5薄膜在室温下对氢气几乎不具敏感性,室温下V2O5/Pd薄膜对氢气具有敏感特性,且不同厚度的薄膜在通氢气前后光的透过率的变化有较大差别。当Pd膜厚度一定时,随着V2O5膜厚的增加,V2O5/Pd薄膜的相对透过率的变化值逐渐增大,当V2O5膜厚度一定时,随着Pd膜厚度的增加,V2O5/Pd薄膜的相对透过率的变化值也逐渐增大。所制备的薄膜样品中,V2O5 (280 nm)/Pd (30nm)薄膜的相对透过率的变化值较大。V2O5 (280 nm)/Pd (30nm)薄膜在4%的氢气浓度下,在波长560 nm处,相对透过率的变化值达到25%左右,且该薄膜对0.01%的氢气也有响应。实验还发现,V2O5/Pd薄膜的相对透过率的变化值与氢气浓度在一定范围内存在着较好的线性关系；(3)在光纤端面上制备了不同厚度的V2O5/Pd薄膜,利用端面反射型光纤传感系统研究了V2O5/Pd薄膜的氢敏特性。结果表明,对于V2O5/Pd薄膜,当Pd膜厚度为20 nm时,V2O5薄膜的厚度对V2O5/Pd薄膜在通氢气前后反射光强的变化值有很大影响。V2O5薄膜厚度越大,其传感器的响应时间变长,但光纤端面相对反射光强变化值增大。当V2O5膜厚为280 nm时,相对反射光强的变化达到约20%,而40 nm的V2O5薄膜,相对反射光强的变化仅为3%。实验结果还显示,在V2O5薄膜表面溅射不同的催化层,对薄膜的氢敏特性有明显影响,Pd-Pt双层催化膜比单一的Pd催化膜效果好；(4)采用拉曼光谱仪原位测试V205和V2O5/Pd薄膜在氢气环境中的拉曼光谱,并分析了薄膜的氢敏机理。结果表明,V2O5/Pd薄膜在与氢气作用过程中,Pd膜主要起催化作用,氢原子扩散到V205层,V5+转变为V4+,导致V2O5/Pd薄膜的透过率发生变化。更多还原

【Abstract】 Hydrogen is renewable and clean new energy. However, one of the major bottlenecks in the applications of hydrogen energy is a lack of reliable and inexpensive hydrogen sensors that can detect possible hydrogen leakage. One of the key issues in developing hydrogen sensors is the synthesis of hydrogen sensitive materials and the preparation of sensitive components. V2O5 thin film is an important gas sensitive material. But hydrogen sensing properties of V2O5/Pd thin films were rarely studied. In this thesis, V2O5/Pd films with different thickness were prepared on glass substrates and the end faces of multimode optic fibers with magnetron sputtering method. V2O5/Pd films were characterized with XRD, AFM, SEM and so on. Hydrogen sensing properties of V2O5/Pd films were tested using a UV-Vis spectrophotometer, the sensitivity of V2O5/Pd films to hydrogen gas was also studied through an optical fiber sensing system, and the sensitive mechanisms were discussed on basis of in situ Raman spectra. The main contents of this thesis and experimental results are as follows:(1) XRD data show that V2O5 and V2O5/Pd films prepared with magnetron sputtering method are amorphous, and the AFM images show that V2O5/Pd thin films possess low surface roughness.(2) V2O5/Pd films with different thickness were deposited on glass substrates, the sensitivity of V2O5 and V2O5/Pd films to hydrogen gas were studied by a UV-Vis spectrophotometer. The results indicate that V2O5 thin film has low sensitivity to hydrogen gas at room temperature and that the V2O5/Pd films are more sensitive to hydrogen gas. After exposed to hydrogen gas, obviously changes in the relative transmittance of the V2O5/Pd films can be observed. When the thickness of Pd thin film is constant, as the thickness of V2O5 thin film increases, the relative transmittance gradually increase; when the thickness of V2O5 thin film is constant, the relative transmittance also increase gradually. By testing the V2O5/Pd films with different thickness, the highest change in relative transmittance can be achieved with the V2O5 (280 nm)/Pd (30 nm) thin film. At the wavelength of 560 nm and 4% hydrogen/nitrogen, the change of the relative transmittance of the film is about 25%, and respondence of this film to 0.01% H2 can be observed. The results also show that there is a good linear relationship between the relative transmittance and hydrogen concentration in a certain hydrogen concentration range.(3) V2O5/Pd films with different thickness were coated on the end faces of multimode optic fibers, the sensitivity of V2O5/Pd films to hydrogen gas was also studied through an optical fiber sensing system. For the V2O5/Pd films, when the thickness of palladium film is 20 nm, different thicknesses of V2O5 thin films have an important effect on the reflected light intensity. When the V2O5 thickness of V2O5/Pd film increase, the response times of the sensor become longer, but the relative reflected light intensity gradually increase. When the V2O5 (280 nm)/Pd (20 nm) exposed to 4% H2, a change of 20% in relative reflected light intensity can be observed. However, for the V2O5 (40 nm)/Pd (20 nm) film, the relative reflected light intensity change only 3%. The results also show that the sensitivity of V2O5 thin film to hydrogen gas is significantly influenced by different catalysts coated onto the V2O5 thin films. The experimental results show that the catalyst effect of the Pd-Pt films is better than that of the Pd films.(4) The sensing mechanism of the V2O5/Pd thin films are discussed on basis of the in situ Raman spectra. The results suggest that Pd thin film mainly palys a role of catalyzer. The insertion of hydrogen atoms into the interlayers of V2O5 causes the transformation of V5+to V4+, and as a result, causes the changes in the transmitance of the films.更多还原