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Investigation of the carbon monoxide gas sensing characteristics of tin oxide mixed cerium oxide thin films.

Durrani SM, Al-Kuhaili MF, Bakhtiari IA, Haider MB - Sensors (Basel) (2012)

Bottom Line: The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive.We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm.Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

View Article: PubMed Central - PubMed

Affiliation: Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia. smayub@kfupm.edu.sa

ABSTRACT
Thin films of tin oxide mixed cerium oxide were grown on unheated substrates by physical vapor deposition. The films were annealed in air at 500 °C for two hours, and were characterized using X-ray photoelectron spectroscopy, atomic force microscopy and optical spectrophotometry. X-ray photoelectron spectroscopy and atomic force microscopy results reveal that the films were highly porous and porosity of our films was found to be in the range of 11.6-21.7%. The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive. We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm. Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

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Sensitivity as a function of biasing voltage for SnO2 mixed CeO2 sensor of thickness 220 nm, CO concentration of 500 ppm and temperature of 430 °C.
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f6-sensors-12-02598: Sensitivity as a function of biasing voltage for SnO2 mixed CeO2 sensor of thickness 220 nm, CO concentration of 500 ppm and temperature of 430 °C.

Mentions: Interaction of gaseous species with a thin film includes two steps [22]. First, oxygen from the ambient adsorbs on the surface of the film, and extracts electrons from the material, ionizes to O2−, O− or O2− depending on the operating temperature of the sensor (Top) [23–25]. The second step involves the reaction of the tested gas (CO in present case) with the adsorbed oxygen species. The introduction of a reducing gas (such as CO) decreases the resistance of the sensing film. For reducing gases, the sensitivity S is defined as (ΔR/RCO) × 100 where ΔR = (Rair − RCO) [4], where Rair is the resistance of the film in air, and RCO is the resistance of the film in the presence of CO. The sensitivity was measured as a function of sensor temperature and biasing voltages for different CO concentrations. Figure 6 shows the dependence of the sensitivity on the sensor bias voltage for SnO2 mixed CeO2 sensor at the optimum temperature of 430 °C, with a CO concentration of 500 ppm. Figure 6 depicts that there was significant variation in response for SnO2 mixed CeO2 sensor as the biasing voltages were increased.


Investigation of the carbon monoxide gas sensing characteristics of tin oxide mixed cerium oxide thin films.

Durrani SM, Al-Kuhaili MF, Bakhtiari IA, Haider MB - Sensors (Basel) (2012)

Sensitivity as a function of biasing voltage for SnO2 mixed CeO2 sensor of thickness 220 nm, CO concentration of 500 ppm and temperature of 430 °C.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376601&req=5

f6-sensors-12-02598: Sensitivity as a function of biasing voltage for SnO2 mixed CeO2 sensor of thickness 220 nm, CO concentration of 500 ppm and temperature of 430 °C.
Mentions: Interaction of gaseous species with a thin film includes two steps [22]. First, oxygen from the ambient adsorbs on the surface of the film, and extracts electrons from the material, ionizes to O2−, O− or O2− depending on the operating temperature of the sensor (Top) [23–25]. The second step involves the reaction of the tested gas (CO in present case) with the adsorbed oxygen species. The introduction of a reducing gas (such as CO) decreases the resistance of the sensing film. For reducing gases, the sensitivity S is defined as (ΔR/RCO) × 100 where ΔR = (Rair − RCO) [4], where Rair is the resistance of the film in air, and RCO is the resistance of the film in the presence of CO. The sensitivity was measured as a function of sensor temperature and biasing voltages for different CO concentrations. Figure 6 shows the dependence of the sensitivity on the sensor bias voltage for SnO2 mixed CeO2 sensor at the optimum temperature of 430 °C, with a CO concentration of 500 ppm. Figure 6 depicts that there was significant variation in response for SnO2 mixed CeO2 sensor as the biasing voltages were increased.

Bottom Line: The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive.We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm.Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

View Article: PubMed Central - PubMed

Affiliation: Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia. smayub@kfupm.edu.sa

ABSTRACT
Thin films of tin oxide mixed cerium oxide were grown on unheated substrates by physical vapor deposition. The films were annealed in air at 500 °C for two hours, and were characterized using X-ray photoelectron spectroscopy, atomic force microscopy and optical spectrophotometry. X-ray photoelectron spectroscopy and atomic force microscopy results reveal that the films were highly porous and porosity of our films was found to be in the range of 11.6-21.7%. The films were investigated for the detection of carbon monoxide, and were found to be highly sensitive. We found that 430 °C was the optimum operating temperature for sensing CO gas at concentrations as low as 5 ppm. Our sensors exhibited fast response and recovery times of 26 s and 30 s, respectively.

Show MeSH