过渡金属掺杂的半导体表面甲烷吸附机理与探测研究

Due to the advantage of fast response time, low cost, simple manufacturing process and so on ,the semiconductor sensor is used for methane gas sensor. However, low sensitivity and poor stability are the important factors that restrict the wide application of semiconductor methane sensors. There are some oxygen defects on the surface of semiconductor sensor, the density of oxygen defects is directly related to the sensitivity and stability of the sensor. The high oxygen defect density can not only increase the sensitivity of the sensor and also reduce the stability of the sensor. Fe, Co and Ni are important catalysts for catalytic conversion of methane, They are easy to adsorb methane molecules and make methane molecules diffuse and activate on their surface. So this project used Fe, Co and Ni transition metal doped semiconductor surface, and make the methane transferred to the semiconductor surface by the phenomenon of spillover to increase the adsorption capacity of methane. To enhance the surface stability, the concentration of oxygen defects on semiconductor surface is designed to be reduced. The concentration of surface oxygen vacancies were mastered by experiment to balance with the oxygen content in surrounding gas. The requirements and preparation methods for the methane sensor were formed to achieve high sensitivity and high stability , and it could be used to guide the actual production of semiconductor methane sensor.

半导体式传感器在响应时间快、成本低、制作工艺简单等方面具有明显的优势而应用于甲烷气体传感器，然而灵敏度低、稳定性差等是制约半导体式甲烷传感器广泛应用的重要因素。在半导体传感器表面存在着一定的氧缺陷，氧缺陷的密度与传感器的灵敏度和稳定性直接相关。过高的氧缺陷密度可以增加传感器的灵敏度，但降低了传感器的稳定性。Fe、Co和Ni是甲烷催化转化重要的催化剂，比较容易吸附甲烷分子又能够让甲烷分子在其表面扩散完成转移和活化.因此，本项目通过Fe、Co和Ni等过渡金属掺杂到半导体表面，再运用“溢流”现象将金属表面吸附的甲烷转移到半导体表面，增加其甲烷吸附能力；同时通过降低半导体表面氧缺陷的浓度的方法增强半导体表面的稳定性。并设计利用实验掌握表面氧缺陷与周围气相氧气维持平衡的浓度。形成一套制备高灵敏度和高稳定性的过渡金属-氧化物复合材料的性能要求和制备方法，为实际半导体甲烷传感器生产提供技术指导。

半导体式传感器在响应时间快、成本低、制作工艺简单等方面具有明显的优势而应用于甲 烷气体传感器，然而灵敏度低、稳定性差等是制约半导体式甲烷传感器广泛应用的重要因素。 在半导体传感器表面存在着一定的氧缺陷，氧缺陷的密度与传感器的灵敏度和稳定性直接相关。过高的氧缺陷密度可以增加传感器的灵敏度，但降低了传感器的稳定性。Fe、Co和Ni是甲烷 催化转化重要的催化剂，比较容易吸附甲烷分子又能够让甲烷分子在其表面扩散完成转移和活化。本项目研究了小分子在过渡金属和氧化物表面吸附和反应的机理，制备了氧缺陷，发现氧缺陷能够活化分子的吸附，但氧化物表面氧缺陷不稳定，通过H2O和O2的吸附，能够将氧缺陷还原，揭示了半导体甲烷传感器在实际运行过程中检测基线飘移的原因。通过机理研究提出实际传感器材料改进方法。应用于甲烷传感器的制备工艺，研发了甲烷传感器，使用寿命延长了50%以上，最低检出浓度检由5%体积分数降至4%，数据准确率和稳定性提高30%以上，并在地下空间防爆探测和地下管网监测中测试应用。实现从基础研究到应用研究的贯通，为实际半导体甲烷传感器生产提供技术指导，为其他应用型基础研究提供了参考。