Thermal Property Modulation Of Titanium Carbide Thin Film For Flexible Humidity Sensor Design

Two-dimensional transition metal carbides（MXene）,such as titanium carbide,possess a layered structure and unique properties similar to graphene.The excellent characteristics of titanium carbide,including high electrical conductivity,outstanding mechanical performance,good chemical stability,and relatively high specific surface area,have led to its widespread application in energy storage,flexible electronics,reinforced materials,sensors,and other fields.While the hydrophilicity of titanium carbide films has received attention,less research has focused on the adsorption and desorption processes of water molecules on the film surface and their impact on the thermal properties.In this study,transient electrothermal methods were used to investigate the physical property changes of Ti₃C₂T_x during the dehydration process,and molecular dynamics simulations were employed to further explore the titanium carbide property change process.Ultimately,a flexible humidity sensor based on titanium carbide film was successfully fabricated,providing a reference for its property research and application.The specific research is as follows:（1）To address the issue of physical property changes during the dehydration process of titanium carbide films,titanium carbide film samples were prepared by an etching method,and the thermal and electrical properties of the samples during the dehydration process were studied in-depth using transient electrothermal methods.The thermal diffusivity of the sample before dehydration was approximately 1.75×10-6 m²s^-1,while after dehydration,the thermal diffusivity was approximately 1.47×10-6 m²s^-1.Dehydration caused a decrease in the thermal diffusivity of the titanium carbide film,and the value of the thermal diffusivity of the titanium carbide sample increased with increasing temperature after dehydration.Further investigation of the response of the physical properties of the titanium carbide film to environmental humidity revealed that the titanium carbide film has significant humidity-sensitive properties,laying the foundation for its application in the field of humidity sensing.（2）To study the physical mechanism of the influence of the water molecule desorption process on the surface of titanium carbide films on their properties,molecular dynamics simulations were used to investigate the desorption behavior of water molecules on the surface of titanium carbide.This simulation method allowed for the observation of the desorption process between water molecules and titanium carbide at the microscopic scale,understanding the interactions between water molecules and titanium carbide,and calculating the thermal conductivity of dehydrated titanium carbide,which decreased from 11.7 W·m^-1K^-1 at 200K to 8.8 W·m^-1K^-1 at 400K.The simulation results contribute to a deeper understanding of the dehydration process of titanium carbide and the changes in its heat transfer characteristics after dehydration.（3）Based on the in-depth study and achievements of titanium carbide properties,a flexible humidity sensor based on titanium carbide film was successfully fabricated and tested for sensitivity,response,recovery,repeatability,and stability.Polyimide（PI）was used as the substrate,with a forked electrode structure prepared by sputtering,followed by coating with titanium carbide solution and high-temperature drying.The sensor’s sensitivity,repeatability,and stability were tested,with a correlation coefficient of 0.98 between the resistance and humidity,a response time of approximately 2.2seconds,and a recovery time of approximately 12 seconds.The effectiveness,repeatability,and stability of the fabricated sensor were fully verified,providing an important reference for the further application of two-dimensional transition metal carbides in sensors.In conclusion,this study used transient electrothermal methods and molecular dynamics to conduct detailed research on the thermal properties of titanium carbide films before and after dehydration.Based on experimental and simulation results,a flexible humidity sensor based on titanium carbide...