Ultrasensitive Detection of Volatile Organic Compounds by a Pore Tuning Approach Using Anisotropically Shaped SnO2 Nanocrystals
Ultrasensitive Detection of Volatile Organic Compounds by a Pore Tuning Approach Using Anisotropically Shaped SnO2 Nanocrystals
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DOI：
10.1021/acsami.6b13006
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发表时间：
2016-12-28
影响因子：
9.5
通讯作者：
Muramatsu, Atsushi
中科院分区：
文献类型：
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作者：
Kida, Tetsuya;Suematsu, Koichi;Muramatsu, Atsushi
具有氧化物纳米结构的气体传感在检测气体化合物的安全监测、过程控制和医疗诊断方面越来越重要。对于此类应用，传感器灵敏度是一个主要标准。在本研究中，为了在极低浓度下灵敏地检测挥发性有机化合物（VOCs），我们使用水热法合成的SnO2纳米立方（13 nm）和不同棒长（50-500 nm）的纳米棒制备了多孔膜。传感器对H-2的响应随晶体尺寸的减小而增大；由最小的纳米立方体制成的薄膜显示出最好的灵敏度，这表明对H-2的传感是由晶体尺寸控制的。相反，对乙醇和丙酮的响应随晶体尺寸和孔径的增大而增大；使用最长纳米棒的多孔膜具有最高的灵敏度。利用Knudsen扩散面反应方程，模拟了气体传感器对乙醇和丙酮的反应，并与实验数据进行了比较。模拟结果表明，乙醇和丙酮的检测受孔径控制。最后，我们实现了对乙醇的超高灵敏度；传感器响应(S)超过S = 100,000，这对应于响应于100 ppm乙醇在250℃下的电阻变化5个数量级。本文基于孔径控制的方法为设计高灵敏度薄膜提供了基础，以满足可检测ppb浓度下各种VOCs的实用传感器的标准。
Gas sensing with oxide nanostructures is increasingly important to detect gaseous compounds for safety monitoring, process controls, and medical diagnostics. For such applications, sensor sensitivity is one major criterion. In this study, to sensitively detect volatile organic compounds (VOCs) at very low concentrations, we fabricated porous films using SnO2 nanocubes (13 nm) and nanorods with different rod lengths (50-500 nm) that were synthesized by a hydrothermal method. The sensor response to H-2 increased with decreasing crystal size; the film made of the smallest nanocubes showed the best sensitivity, which suggested that the H-2 sensing is controlled by crystal size. In contrast, the responses to ethanol and acetone increased with increasing crystal size and resultant pore size; the highest sensitivity was observed for a porous film using the longest nanorods. Using the Knudsen diffusion surface reaction equation, the gas sensor responses to ethanol and acetone were simulated and compared with experimental data. The simulation results proved that the detection of ethanol and acetone was controlled by pore size. Finally, we achieved ultrahigh sensitivity to ethanol; the sensor response (S) exceeded S = 100 000, which corresponds to an electrical resistance change of 5 orders of magnitude in response to 100 ppm of ethanol at 250 degrees C. The present approach based on pore size control provides a basis for designing highly sensitive films to meet the criterion for practical sensors that can detect a wide variety of VOCs at ppb concentrations.