Abstract
Monitoring and detecting carbon monoxide (CO) are critical because this gas is toxic and harmful to the ecosystem. In this respect, designing high-performance gas sensors for CO detection is necessary. Zinc oxide-based materials are promising for use as CO sensors, owing to their good sensing response, electrical performance, cost-effectiveness, long-term stability, low power consumption, ease of manufacturing, chemical stability, and non-toxicity. Nevertheless, further progress in gas sensing requires improving the selectivity and sensitivity, and lowering the operating temperature. Recently, different strategies have been implemented to improve the sensitivity and selectivity of ZnO to CO, highlighting the doping of ZnO. Many studies concluded that doped ZnO demonstrates better sensing properties than those of undoped ZnO in detecting CO. Therefore, in this review, we analyze and discuss, in detail, the recent advances in doped ZnO for CO sensing applications. First, experimental studies on ZnO doped with transition metals, boron group elements, and alkaline earth metals as CO sensors are comprehensively reviewed. We then focused on analyzing theoretical and combined experimental–theoretical studies. Finally, we present the conclusions and some perspectives for future investigations in the context of advancements in CO sensing using doped ZnO, which include room-temperature gas sensing.
Highlights
Carbon monoxide (CO) is a pollutant gas that can be toxic if inhaled in large amounts, and its release outdoors contributes to air pollution [1,2,3]
In some cases, various hazardous gases are detected successfully and efficiently via the parameters shown in Table 1 [22,23]. It is defined as a change in some physical properties when the device is exposed to target species. It is the ability of a gas sensor to detect high sensitivity to a specific gas among various types of gases at the same concentration level
A higher CO response for the Al-doped zinc oxide (ZnO) sensors was observed at 80 ppm and 250 ◦ C, with response and recovery times of 15 and 7 s, respectively
Summary
Carbon monoxide (CO) is a pollutant gas that can be toxic if inhaled in large amounts, and its release outdoors contributes to air pollution [1,2,3]. It is defined as a change in some physical properties when the device is exposed to target species It is the ability of a gas sensor to detect high sensitivity to a specific gas among various types of gases at the same concentration level. Among various MOSs, those based on ZnO have become widely manufactured and utilized because of their outstanding characteristics, such as a bandgap around 3.4 eV at room temperature [31,32,33], high optical transparency in the visible region (>80%), n-type conductivity, and high exciton binding energy in the order of 60 meV [31,34] They have a versatile morphology, rendering them suitable for usage in different industrial applications, including gas sensor devices, by their potential to detect various toxic gases. We present conclusions, and the current challenges are outlined
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