Pt/TiO_2表面状态对气敏特性的影响

Influence of Surface States on Gas Response Properties of Pt/TiO_2

通过浸渍法用H2PtCl6溶液修饰TiO2厚膜,经过不同的处理工艺,获得表面负载Pt粒子的Pt/TiO2厚膜.采用XRD和SEM分析了Pt/TiO2的物相结构和表面形貌,并通过电阻氧分压关系计算Pt/TiO2厚膜活化能.然后分别通过静态和动态测试法,表征了Pt/TiO2厚膜在H2/O2中的稳态阻值和动态响应时间.结果表明:受"spill-over"机制影响,Pt/TiO2厚膜在H2/O2气氛下的稳态电阻与Pt的散布状态有关.而样品响应时间不仅与Pt粒子的分布有关,还受表面活化能的影响,在Pt散布基本相同情况下,活化能越低,样品响应速度越快.

Pt/TiO2 thick film gas sensors were modified by dipping method in H2PtCl6 contained solution. In order to get different Pt/TiO2 surface states, the thick films were treated with different process. Microstructural and morphological characteristics were investigated by XRD and SEM. The resistance-oxygen partial pressure relationship was used to calculate activation energy （E） of this film. Steady-state resistance and dynamic response of the sensor exposed to H2/O2 were tested, separately. The results indicated that the steady-state resistance which affected by ＂spill-over＂ effect arose from the Pt distribution states. However, the response time was associated with the activation energy （E）. Sensors with lower activation energy exhibited a faster rate of response when the magnitude of response was approximately uniform.