钴掺杂二氧化锡基氢气传感器气敏特性研究

Research on Hydrogen Sensing Properties of Cobalt Doped SnO_2 Based Chemical Gas Sensor

氢气(H_2)是溶解在变压器油中的重要故障特征气体,对油中溶解的H_2气体浓度进行在线监测能实时有效反映变压器的运行状况。针对传统的二氧化锡基气体传感器检测油中溶解气体存在工作温度较高,气体响应较低的问题,提出一种用金属钴Co掺杂纳米二氧化锡SnO_2基传感器检测变压器油中溶解气体的方法,介绍其制备方法研制气体传感器并测试H2气敏特性,同时基于第一性原理对其敏感机理进行了探讨。结果表明:金属Co掺杂SnO_2后传感器的最佳工作温度降低至300℃,对50μL/L H_2的灵敏度增到12.16,Co掺杂后SnO_2的导带负移,在费米能级附近出现了新的掺杂能级,增大了SnO_2表面的导电性能,H2吸附在Co-SnO_2表面时,价带顶附近区域出现了新的表面态,有利于载流子在价带和导带间的转移,从而改善传感器的气敏性能。

Hydrogen（ H2） is one of the most important fault gases dissolved in power transformer oil,and on-line monitoring the concentration of H2 in oil could reflect the operational state of transformer timely and effectively. Considering the limitations of higher operating temperature and lower gas response,the paper proposed a cobalt-doped nano-SnO2 based gas sensor to detect fault gas H2 dissolved in transformer oil. The gas sensor was prepared with the side heated preparation process and H2 sensing properties were measured. Furthermore,based on the first principles calculations,an atomic level understanding of adsorption process and the sensing mechanism were investigated. Results indicate that the optimum working temperature of SnO2 based gas sensor decreases and its sensing response increases obviously after Co dopant. New doping levels and surface states appear near the Fermi level of SnO2 crystal,which could promote the electrical conductivity and the charge transfer between H2 and SnO2 in gas sensing process.