NO2 Sensing Properties of Cr2WO6 Gas Sensor in Air and N2 Atmospheres.

Yi Wu,Chen Tian,Yuhang Liu,Meng Yan,Zhongqiu Hua

doi:10.3389/fchem.2019.00907

Abstract

Gas sensors were fabricated from Cr2WO6 nanoparticles for NO2 detection. Low dimensional materials Cr2WO6 were prepared by a wet chemistry method followed by hydrothermal treatment. The morphology of the nanoparticles and their sensing properties to NO2 were investigated in both dry and humid conditions. Additionally, the sensing response was also characterized in a non-oxygen condition. It was concluded that the sensor responses in N2 conditions were higher than that in air conditions at 200°C. Moreover, the sensing characteristics were inhibited by water vapor at 200°C. The oxygen adsorption behavior was also investigated to verify the basic sensing mechanism of Cr2WO6 in the absence and presence of NO2 and water vapor separately. Based on the power law response, it was indicated that both NO2 and water vapor have a strong adsorption ability than oxygen ions of Cr2WO6 sensors.

Highlights

National nitrogen oxide (NOx) emissions were 20.6 million metric tons (Mt) in 2015, with annual growth rates of 5.9% since 1949 in China (Richter et al, 2005; Sun et al, 2018)
In order to obtain a high purity of Cr2WO6 phase, a high sintering temperature of 1,000◦C was used and the crystal structure was characterized by X-ray diffraction (XRD)
The morphology of Cr2WO6 powders was characterized by SEM and transmission electron microscopy (TEM)

Summary

INTRODUCTION

National nitrogen oxide (NOx) emissions were 20.6 million metric tons (Mt) in 2015, with annual growth rates of 5.9% since 1949 in China (Richter et al, 2005; Sun et al, 2018). Gas sensors based on P-type MOS materials have been reported to have a sensitive and selective response to NO2 with a low cross-sensitivity to humidity (Nguyen and El-Safty, 2011; Stanoiu et al, 2012). It was reported that the NO2 sensors based on Cr2O3 showed a selectivity relative to CO and low crosssensitivity to humidity, which was due to the higher surface reactivity toward NO2 than CO through the electrical resistance and work function changes both in dry and humid air (Stanoiu et al, 2012). It was found that sensors based on P-type Cr2WO6 were very sensitive to NO2 even with a high humid condition.

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT