Development of nanocrystalline TiO2–Er2O3 and TiO2–Ta2O5 thin film gas sensors: Controlling the physical and sensing properties
Development of nanocrystalline TiO2–Er2O3 and TiO2–Ta2O5 thin film gas sensors: Controlling the physical and sensing properties
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DOI：
10.1016/j.snb.2009.05.026
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发表时间：
2009-08
影响因子：
8.4
通讯作者：
M. Mohammadi;D. Fray
中科院分区：
文献类型：
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作者：
M. Mohammadi;D. Fray
对溶胶-凝胶法制备的纳米结构和介孔结构的单、二元金属氧化物TiO2、TiO2 - er2o3和TiO2 - ta2o5薄膜气体传感器进行了系统比较。在tio2薄膜中引入二次相可以通过两种机制提高气敏性，首先是由于锐钛矿相可以容纳更多的吸附氧，从而抑制锐钛矿向金红石的转化；其次是由于更高的表面积为气体分子吸附提供了更多的活性位点，从而延缓了晶粒的生长。在200℃的低温下，二元金属氧化物气体传感器对低浓度的CO和no2气体表现出了显著的响应，从而提高了传感膜的热稳定性，降低了传感膜的功耗。当TiO2:Ta2O5的摩尔比为50:50 （TT11）时，TiO2 - Ta2O5传感器对200℃下所有CO浓度的响应都最高；当TiO2:Er2O3的摩尔比为75:25 （TE31）时，TiO2 - Er2O3传感器对相同温度下所有no2浓度的响应都最高。对于400ppm CO， TE31和TT11传感器的响应幅度分别为10.5和11.7。此外，TE31和TT11传感器对10ppm NO2的响应幅度分别为4.5和3.8。校准曲线显示，两种气体的所有传感器都遵循幂律（S=A[gas]B）（其中S为传感器响应，系数A和B为常数，[gas]为气体浓度）。本研究中获得的传感器的响应幅度优于以往研究中报道的基于二氧化钛的传感器。
A systematic comparison of single and binary metal oxide TiO2, TiO2–Er2O3and TiO2–Ta2O5thin film gas sensors with nanocrystalline and mesoporous microstructure, prepared by sol–gel route, was conducted. The gas sensitivity was increased by secondary phase introduction into TiO2film via two mechanisms, firstly due to the inhibition of anatase-to-rutile transformation, since the anatase phase accommodates larger amounts of adsorbed oxygen, and secondly due to the retardation of grain growth, since the higher surface area provides more active sites for gas molecule adsorption. The binary metal oxide gas sensors exhibited a remarkable response towards low concentrations of CO and NO2gases at low operating temperature of 200°C, resulting in improving the thermal stability of sensing films as well as reducing their power consumption. TiO2–Ta2O5sensor with molar ratio of TiO2:Ta2O5=50:50 (TT11) showed the highest response towards all CO concentrations operated at 200°C, whereas TiO2–Er2O3sensor with molar ratio of TiO2:Er2O3=75:25 (TE31) had the highest response towards all NO2concentrations at the same operating temperature. The response magnitude of 10.5 and 11.7 was achieved for TE31 and TT11 sensors towards 400ppm CO, respectively. In addition, the response magnitude of 4.5 and 3.8 was achieved for TE31 and TT11 sensors towards 10ppm NO2, respectively. The calibration curves revealed that all sensors followed the power law (S=A[gas]B) (where S is sensor response, coefficients A and B are constants and [gas] is gas concentration) for the two kinds of gases. The response magnitude of the sensors obtained in this work is superior to TiO2-based sensors reported in previous studies.