CO sensing mechanism with WO3 based gas sensors (original) (raw)

Abstract

The interaction between CO and WO 3 based gas sensors was investigated in operando conditions by using resistance, catalytic conversion and DRIFTS measurements. The experimental results are showing that the sensing involves the reduction of the metal oxide, which is the opposite of the case of SnO 2 , the other extremely relevant material for semiconducting oxides based gas sensors.

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What explains the mechanism of CO detection by WO3 sensors?add

The study reveals that the CO detection in WO3 sensors likely involves the reduction of the material, utilizing lattice oxygen to produce CO2. This reduction reaction distinguishes its sensing mechanism from that of SnO2-based materials.

How does oxygen concentration affect WO3 sensor performance with CO exposure?add

The paper finds that increasing oxygen concentration to 150 ppm decreases sensor signals while increasing CO2 production. This indicates an equilibrium between oxygen vacancies' generation and cancellation influenced by the surrounding oxygen levels.

What experimental methods were used to analyze CO sensing in WO3?add

Conductance, catalytic conversion, and DRIFTS measurements were employed to investigate CO sensing performance in WO3. The study particularly assessed sensor responses under various oxygen background conditions, including almost total absence of oxygen.

What role do oxygen vacancies play in the sensing mechanism of WO3?add

The findings suggest that oxygen vacancies in WO3 are crucial for sensing, as their ionization decreases resistance during CO interaction. This interaction is essential in understanding the gas sensing mechanisms compared to SnO2 materials.

What are the unique contributions of WO3 compared to SnO2 in gas sensing?add

Unlike SnO2, WO3 sensors can produce CO2 even in low oxygen conditions, indicating a direct material reduction. This significant deviation in sensing behavior necessitates re-evaluating existing understanding of reducing gas interactions.

Figures (2)

Fig. 1. Time dependence of the resistance during CO exposure (10, 30, 70, 100 ppm) in the absence of oxygen at 300°C. The amount of CO and CO; in the exhaust is shown in the upper part. Fig. 2. Time dependence of the resistance during CO exposure (10, 30, 70, 100 ppm) in the presence of 150 ppm of oxygen. The amount of CO and CO in the exhaust is shown in the upper part.

Fig. 1. Time dependence of the resistance during CO exposure (10, 30, 70, 100 ppm) in the absence of oxygen at 300°C. The amount of CO and CO; in the exhaust is shown in the upper part. Fig. 2. Time dependence of the resistance during CO exposure (10, 30, 70, 100 ppm) in the presence of 150 ppm of oxygen. The amount of CO and CO in the exhaust is shown in the upper part.

Fig. 3. DRIFT absorbance spectra for WO3 sensor in the absence of oxygen, in the upper part (red), and in dry synthetic air, in the lower part (blue), at 300°C during exposure to 250 ppm of CO. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

Fig. 3. DRIFT absorbance spectra for WO3 sensor in the absence of oxygen, in the upper part (red), and in dry synthetic air, in the lower part (blue), at 300°C during exposure to 250 ppm of CO. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of the article.)

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