MXenes gas sensor for air pollutant detection

已传文件：photo/20204993437814.png

【Research Background】

The pursuit of miniaturization of devices has greatly promoted research in the field of two-dimensional nanomaterials. The discovery of graphene with extraordinary physical and electronic properties has inspired people‘s enthusiasm to find other two-dimensional nanostructures. Large specific surface area, excellent mobility of charge carriers, massless Dirac fermions, robust mechanical properties and thermal stability are some of the exciting characteristics of graphene, these characteristics make it promising in energy storage, Plays a role in catalysis, spintronics and gas sensing applications. Based on a large number of theoretical and experimental studies, researchers believe that two-dimensional nanostructures have great potential for technical application in the future development direction of nanodevices.

A layered material commonly referred to as "MXene" has recently appeared in the field of two-dimensional nanostructures. So far, more than 20 experimental synthesis of MXene system have been reported, and dozens of theoretical predictions have been made. The excellent physical, mechanical and chemical properties make it play a huge role in various technical applications such as water purification, energy storage and hazardous gas detection. Carbide MXenes (Ti 2 C, Ti 3 C 2 ) are the most widely studied candidate products of the MXene family, and their excellent performance in gas sensing and energy storage has been reported. Due to its high surface area, adjustable electronic and chemical properties, and its ability to work at room temperature, MXenes is attractive for gas sensing applications.

【Achievement Introduction】

Recently, Professor Naresh Kumar Jena Uppsala University (Uppsala University) and Professor Wei Luo in internationally renowned academic journal Applied Materials Today published an article on the subject is: Exploring TWO-dimensional M 2 NS 2 MXenes (M = Ti, V) Based on the research paper of gas sensors for air pollutants , they explored the sensing tendency of M 2 N MXene sheets (M = Ti, V) containing S functional groups to various gas polymers. The selected gas molecules, including CO 2 , CO, CH 4 , NH 3 , NO, NO 2 , H 2 S and SO 2 , have adverse effects on the climate, especially on human health. The greenhouse effect is one of the many reasons for controlling and monitoring these gases in the atmosphere. Therefore, it is inevitable to monitor the leakage of these gases in the atmosphere to avoid serious health hazards. The MXenes nitride with S functional group has not been used for sensing applications. Therefore, the recent work of this paper is a step towards the development of nano-scale sensing devices.

【Graphic introduction】

Figure 1.  Model diagram and state density diagram of  Ti 2 NS 2 and V 2 NS 2 MXene sheets.

Figure 2.  Schematic diagram of various gas sensing principles.

Figure 3. The  surface density of the charge of theadsorbed gas on the Ti 2 NS 2 sheet.

Figure 4.  Total state density (TDOS) graphof gas-adsorbed Ti 2 NS 2 MXene sheet.

Figure 5. The surface density of the charge of the adsorbed gas on the V 2 NS 2 sheet.

Figure 6.  Total state density (TDOS) graph of gas-adsorbed V 2 NS 2 MXene sheet.

Figure 7. Schematic diagram of the nanodevice setup with Ti 2 NS 2 sheets on the top and sides.

Figure 8. Zero deviation transmission of Ti 2 NS 2 and V 2 NS 2  MXene sheets before and after adsorbing gas molecules.

Figure 9. Sensitivity of different gas molecules on Ti 2 NS 2 and V 2 NS 2 surfaces.

【Summary of this article】

     In this paper , the sensing capability of the M 2 N (M = Ti, V) MXene sheet on the S surface functional group has been studied. This material has not been previously developed to detect toxic gases. The results show that Ti 2 NS 2 can be used as sensing materials for NO, NO 2 , H 2 S and SO 2 gases. Similarly, V 2 NS 2 tablets have a similar trend, in fact, it shows a higher sensitivity to these gas molecules. Charge transfer analysis confirmed that NO molecules share a considerable portion of the charge with Ti 2 NS 2 sheets, which leads to changes in the molecular structure. DOS analysis showed that the magnetic molecules NO and NO 2 pair of of Ti 2 the NS 2 and V2NS 2 generate a magnetic adsorption. The adsorption energy of NO and NO 2 molecules on the MXene surface is ideal for reversible adsorption / desorption, because M 2 NS 2 tablets can easily maintain their original state after detecting gas molecules. To further confirm this finding, the transfer function of the MXene sheet was calculated based on the MXene-based nanodevice sensor based on resistance measurement, thereby estimating the effect of gas adsorption. All our results show that this device is feasible, S-functionalized sensors can optimize the function, especially NO and NO 2. The discovery is timely and can immediately attract the attention of the experimenter.

Literature link:

https://dx.doi.org/10.1016/j.apmt.2020.100574.

Source: MXene Frontier