Sensors B. Chemical: Three-dimensional wrinkled MXene Ti3C2Tx/ZnO spheres for room temperature flexible resistive NO2 gas sensor

MXene is a two-dimensional star material that is even hotter than graphene. As an advanced MXene manufacturer, North Konami offers special offers, 10% off mxene and other materials, and North Konami launches new mesoporous material products with more preferential prices , waiting for you to spike! picture


MXenes are an emerging class of 2D materials, including 2D transition metal carbides, nitrides, and carbonitrides. MXenes have shown potential applications in gas/humidity sensing, energy storage systems, water purification, and electromagnetic interference shielding. According to the reported gas sensing work, the signal-to-noise ratio of gas sensors based on pure 2D MXene nanosheets is higher than that of other 2D gas sensing materials, such as graphene, transition metal dichalcogenides, and black phosphorus. However, MXene can cause severe aggregation after drying and lose a large specific surface area. Therefore, the response and selectivity of gas sensors based on pure 2D MXene nanosheets are very poor and further improvements are needed to improve their practicality.


Recently, Professor Lu Geyu of Jilin University published a research paper titled: Flexible resistive NO2 gas sensor of three-dimensional crumpled MXene Ti3C2Tx/ZnO spheres for room temperature application in the internationally renowned academic journal Sensors and Actuators: B. Chemical. The method of ultrasonic spray pyrolysis demonstrates aggregation-resistant 3D wrinkled MXene Ti3C2Tx spheres, providing MXenes with high specific surface area, enabling a large adsorption surface for the target gas. Furthermore, we composite ZnO nanoparticles with 3D wrinkled MXene Ti3C2Tx spheres to create more activated adsorption sites. The above improvements greatly improve the NO2 sensitivity, selectivity, responsiveness, and recovery of the MXene sensor. In addition, room temperature sensing of NO2 in flexible devices was realized using polyimide (PI) substrates, and the sensing process between MXene and NO2 was deeply explored. Based on the above sensing performance, new sensing strategies and flexible gas sensing devices are proposed.



Figure 1. Schematic diagram of the fabrication and flexible gas sensing device of 3D MXene wrinkled spheres and 3D MXene wrinkled spheres/ZnO.



Figure 2. Morphology and elemental distribution of MXene 3D wrinkled spheres.


Figure 3. Morphology and elemental distribution of 3D MXene spheres/ZnO.

Figure 4. The structure, phase characterization, and surface analysis of MXene sheets, 3D wrinkled MXene spheres, and 3D wrinkled MXene spheres/ZnO were investigated.


Figure 5. The selectivity, concentration sensitivity, and recovery properties of flexible gas sensors based on MXene flakes, 3D MXene spheres, and 3D MXene spheres/ZnO were investigated.



Figure 6. Flexible NO sensing performance of the wrinkled MXene/ZnO-based flexible gas sensor, the effect of humidity on NO sensing, and the difference between ammonia sensing and NO sensing.


Figure 7. Schematic diagram of gas adsorption.


Figure 8. Density functional theory (DFT) simulations of NO molecular adsorption on different materials.


     In summary, this paper introduces the preparation and modification of MXene Ti3C2Tx 3D wrinkled spheres by a reliable and effective ultrasonic spray pyrolysis method, and other 2D materials can also be modified by a similar method. The three-dimensionally wrinkled MXene not only maintains the high specific surface area of the MXene sheet, but also provides a stable and uniform pathway for compounding with other materials. The high specific surface area, the possibility of increasing the response sites, and the high gas-sensing material enable this paper to apply 3D wrinkled MXene spheres to gas sensors. Compared with MXene flakes and 3D wrinkled MXene spheres, the 3D wrinkled MXene spheres/ZnO achieved reversible sensing of NO2 while significantly improving the selectivity and response to NO2. The response to 100 ppm NO2 increased from 27.27% to 41.93%, and the recovery increased substantially from 30% to ~100%. MXene spheres/ZnO exhibit high NO sensing performance due to the folding of their surfaces and the appearance of pn heterojunctions resulting in defective MXene spheres and ZnO nanoparticles. The three-dimensional wrinkled MXene sphere structure provides a new idea for the chemical sensing of MXenes, further promotes the application of MXenes in gas sensors, and thus provides a reference for exploring the gas sensing mechanism of MXenes.