Effect of Humid Aging on the Oxygen Adsorption in SnO2 Gas Sensors

Abstract

To investigate the effect of aging at 580 °C in wet air (humid aging) on the oxygen adsorption on the surface of SnO2 particles, the electric properties and the sensor response to hydrogen in dry and humid atmospheres for SnO2 resistive-type gas sensors were evaluated. The electric resistance in dry and wet atmospheres at 350 °C was strongly increased by humid aging. From the results of oxygen partial pressure dependence of the electric resistance, the oxygen adsorption equilibrium constants (K1; for O− adsorption, K2; for O2− adsorption) were estimated on the basis of the theoretical model of oxygen adsorption. The K1 and K2 in dry and wet atmospheres at 350 °C were increased by humid aging at 580 °C, indicating an increase in the adsorption amount of both O− and O2−. These results suggest that hydroxyl poisoning on the oxygen adsorption is suppressed by humid aging. The sensor response to hydrogen in dry and wet atmosphere at 350 °C was clearly improved by humid aging. Such an improvement of the sensor response seems to be caused by increasing the oxygen adsorption amount. Thus, the humid aging offers an effective way to improve the sensor response of SnO2 resistive-type gas sensors in dry and wet atmospheres.

Advancements in Microfabricated Gas Sensors and Microanalytical Tools for the Sensitive and Selective Detection of Odors

“…Moreover, due to the simple and compact design of chemiresistors, these devices can be easily miniaturized and implemented onto flexible substrates, which shows great potential for their implementation in wearable applications [ 106 , 107 ]. On the other hand, similar to potentiometric gas sensors, main concerns of chemiresistors are their sensitivity to environmental factors (i.e., especially humidity), as well as their lack of selectivity, which might lead to the sensor’s baseline drift or ineffective performance in complex gas mixtures [ 108 ].…”

Acetone Sensing Properties and Mechanism of SnO2 Thick-Films

“…Among the semiconductor metal oxides used in gas sensors, SnO 2 has received considerable attention in science and technology for many years. SnO 2 with a wide band gap of 3.6 eV is a significant functional material applicable for solar cells, catalysis, transparent electrodes, and, particularly, in gas sensor devices because of its unique optical, catalytic, and electrical properties [ 1 , 2 , 3 , 4 , 5 , 6 ]. It has been widely used to detect toxic chemicals such as CH 4 , H 2 , C 2 H 5 OH, gasoline, CO, C 2 H 2 , NO 2 , NO, and H 2 S [ 7 ].…”

“…Acetone can be used as a breath marker for the diagnosis of diabetes because the concentration of acetone in healthy individuals’ breath varies from 0.3 to 0.9 ppm and in the exhaled air of diabetic patients exceeds 1.8 ppm [ 18 ]. A chemiresistive type sensor using SnO 2 is considered as an exhalation gas sensor because of its excellent reactivity with volatile organic compounds (VOCs), easy fabrication processes, and the possibility of miniaturization of portable integration [ 3 , 4 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. For example, L. Cheng et al [ 3 ] have developed Y-doped SnO 2 hollow nanofibers for the detection of acetone.…”

“…For example, L. Cheng et al [ 3 ] have developed Y-doped SnO 2 hollow nanofibers for the detection of acetone. L.P. Qin et al [ 4 ] reported the effect of temperature on the acetone-sensing properties of SnO 2 nanowires. Also, J. Zhao et al [ 19 ] reported the acetone vapor sensing performance of SnO 2 thin films prepared by dip-coating.…”

Features of water vapor adsorption and desorption on the surface of non-stoichiometric tin dioxide films

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