Abstract
CeO2/ZnO-heterojunction-nanorod-array-based chemiresistive sensors were studied for their low-operating-temperature and gas-detecting characteristics. Arrays of CeO2/ZnO heterojunction nanorods were synthesized using anodic electrodeposition coating followed by hydrothermal treatment. The sensor based on this CeO2/ZnO heterojunction demonstrated a much higher sensitivity to NO2 at a low operating temperature (120 °C) than the pure-ZnO-based sensor. Moreover, even at room temperature (RT, 25 °C) the CeO2/ZnO-heterojunction-based sensor responds linearly and rapidly to NO2. This sensor’s reaction to interfering gases was substantially less than that of NO2, suggesting exceptional selectivity. Experimental results revealed that the enhanced gas-sensing performance at the low operating temperature of the CeO2/ZnO heterojunction due to the built-in field formed after the construction of heterojunctions provides additional carriers for ZnO. Thanks to more carriers in the ZnO conduction band, more oxygen and target gases can be adsorbed. This explains the enhanced gas sensitivity of the CeO2/ZnO heterojunction at low operating temperatures.
Highlights
Nitrogen dioxide (NO2 ) is a harmful gas that threatens human survival [1]
The sensor’s response changed slightly after long-term stability testing (10 days). These experimental results show that sensors based on CeO2 /ZnO-2 composites provide the possibility of NO2 gas detection at low temperatures
We successfully synthesized a NO2 gas sensor based on a CeO2 /ZnO
Summary
Nitrogen dioxide (NO2 ) is a harmful gas that threatens human survival [1]. Vehicle exhaust fumes and boiler exhaust emissions are among the principal sources of man-made. The rapid and accurate detection of NO2 is critical for human health and environmental protection; research on nitrogen dioxide sensors is very important. The disadvantages of MOS-based gas-sensing materials include excessively high operating temperatures and low selectivity, which limit their use in practical engineering applications. Different material morphologies have a noticeable influence on the gas-detecting performance of MOS-based gas sensors. Several researchers have paired ZnO with other MOSs to make heterojunctions in order to enhance ZnO’s gas-detection performance, which has proven beneficial. Compared to the pure ZnO operating temperature of 300 ◦ C, the modified sample exhibits better gas-sensing performance at room temperature (RT), possesses a faster response recovery time, and achieves the best response to NO2 at 120 ◦ C, demonstrating the practical potential of the sensor for use at low operating temperatures
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