Preparation And Gas Sensitive Properties Of MXene Aerogel

Gas sensors are an important tool for obtaining gas information and play an important role in different fields such as industrial production,aerospace,medical and health care and daily life.Currently,the more widely used metal oxide semiconductor gas sensors have defects such as high operating temperature,short lifetime,and low sensitivity,which limit their application scope.Therefore,it is important to develop gas sensors that can operate at room temperature with high sensitivity,selectivity and stability.And with the development of flexible wearable devices,the performance of gas sensors has put forward higher requirements.MXene is a general term for two-dimensional transition metal carbides,nitrides and carbonitrides,which have high electrical conductivity,large specific surface area,narrow band gap,strong electron transfer capability and easy functionalization.However,two-dimensional MXene has the disadvantage that the material is easy to stack and cannot make effective contact between the surface active groups and the detection gas.Therefore,this paper focuses on the study of three-dimensional（3D）MXene aerogel sensors and investigates the gas-sensitive performance of the sensors to methanol and triethylamine by preparing different composite aerogel sensors.The details are as follows:（1）Fe²⁺/Mxene/BC aerogel was obtained by introducing Fe Cl₂ and bacterial cellulose（BC）in composite preparation.The Fe²⁺/MXene/BC aerogel sensor exhibited excellent sensing performance for methanol at room temperature.The sensor achieved a response value of 2.66for 10 ppm methanol gas,a short response time（15 s）,and excellent bending and humidity detection capabilities.The Fe²⁺/MXene/BC aerogel sensor has excellent methanol detection capabilities mainly because the introduction of Fe²⁺disrupts the electrostatic repulsion between MXene lamellae,while the composite with BC forms a stable three-dimensional honeycomb-like This prevents the stacking of MXene layers and allows the surface functional groups to play a better role in gas adsorption.（2）Zn O was formed on MXene nanosheets by employing a mild method,and later compounded with BC to form Zn O/MXene/BC aerogel.The prepared Zn O/MXene/BC aerogel gas sensor can be used to detect methanol gas at room temperature.The response value for methanol gas at 5 ppm is 1.12,the response time is 50 s,and the recovery time is 20 s.Meanwhile,the detection capability of the sensor for methanol gas in high humidity is significantly improved,and the response value for methanol gas at 5 ppm is 1.41 at a humidity of 79.3%.The good methanol sensing performance of the Zn O/MXene/BC aerogel sensor is due to following factors:Firstly,the aerogel has a three-dimensional porous structure,which can give full play to the sensing ability of MXene,secondly,Zn O is attached to the surface of MXene sheet layer,which can provide more gas adsorption sites and surface defects,while forming heterojunctions to enhance the synergistic effect of adsorbents on the material surface.（3）Co²⁺/PANI/MXene/BC aerogel was prepared by adding Co Cl₂,BC compounded with MXene,followed by the addition of conducting polymer polyaniline（PANI）.A Co²⁺/PANI/MXene/BC aerogel gas sensor was constructed with good selectivity for triethylamine gas.The sensor can be used to detect very low concentrations of triethylamine gas with a response value of 1.16 for 50 ppb triethylamine gas,while detecting a wide concentration range of triethylamine gas in the range of 50 ppb-30 ppm.The good triethylamine gas detection performance of the sensor can be attributed to the fact that the introduction of Co²⁺promotes the linkage between MXene sheets and the-OH linkage with the MXene surface,so that the material maintains the sheet structure and prevents stacking,while the PANI/BC coupling forms an aerogel,which enhances the electron transfer capability with the detection gas,and enables the functional groups on the MXene surface to be in full contact with the test gas.Improve the sensor gas sensitivity performance.Overall,by preparing MXene aerogel sensors with three-dimensional structure,the stacked extrusion of nanosheet layers is effectively avoided,so that the gas adsorption sites of the material can be fully contacted with the detection gas and the gas adsorption capacity is improved.Meanwhile,the three-dimensional structure of the aerogel sensor has good room temperature detection capability,high mechanical strength and bendability,which provides a reference for exploring its application in flexible wearable devices.