Sensing Properties In MXene/Graphene Composite Structure

Two-dimensional materials(graphene,MXene,metal oxides et al.),due to their unique properties,have a wide range of applications in the field of electronic sensing,such as biosensors,temperature/humidity sensors,gas sensors.These sensors,which can be integrated on a wearable wristband or breathing mask,are often used for non-invasive blood glucose detection,lactic acid detection,and nitrogen detection.In recent years,researchers have focused on improving the performance of sensors,while little investigation has been made into the internal microstructure of materials and the transport behaviour of sensors.However,the internal microstructure(e.g.nanopores,nanochannels)influences the transport of electrons/ions to some extent,which further affects the sensor's sensing performance.Therefore,it is necessary to investigate the internal microstructure of materials and the internal transport behavior of sensors.Graphene has excellent mechanical,electrical,thermal and optical properties as a two-dimensional carbon material.However,graphene is easy to agglomerate,resulting in poor electrochemical activity,which limits its application in biosensing.MXene,which has excellent electrochemical activity and biocompatibility,interacts with graphene to form two-dimensional composite materials in order to reduce self-stacking.At present,researchers have carried out studies on the applications of MXene and graphene nanomaterials in the non-invasive detection of diabetes,including the detection of glucose concentration in human extracorporeal fluid and the detection of acetone content in exhaled breath.This thesis takes MXene/graphene composite material as the starting point,focusing on its application in the non-invasive detection of diabetes.The main research contents and results are as follows:(1)Research on glucose sensor based on Ti₃C₂-rGO composite structure.First,the Ti₃C₂-rGO hybrid film was prepared by electrostatic self-assembly technology,and the relationship between the structure and performance of the hybrid film was explored.The good electrostatic interaction between MXene and rGO nanosheets reduces the self-stacking of the two,forms porous intercalation structures,expands the interlayer spacing and obtains the effective nanoscale transport channels,thereby increasing active sites,shortening the ion diffusion path,and improving the electrochemical performance of the hybrids,making it better used in sensing elements.Then we designed and prepared a glucose sensor based on Ti₃C₂-rGO composite membrane and explored its sensing performance and internal transport behavior(charge transfer and ion diffusion).The device has good stability,repeatability and selection specificity.By exploring the diffusion of H⁺ions at different frequencies,it is proved that the diffusion in the low-frequency range plays an important role in the sensing mechanism of the glucose sensor.In addition,the inter-layer spacing,H⁺ions diffusion and the interrelationship of sensitivity further reveal that H⁺ion diffusion is the main source of enhanced glucose sensitivity.This work provides further help for the applications of Ti₃C₂-rGO composite structure and other two-dimensional materials in glucose sensors.(2)Research on acetone gas sensor based on Ti₃C₂-rGO composite structure.In this work,the designed Ti₃C₂-rGO gas sensor compared with the pure MXene gas sensors,obtained a higher gas sensitivity response at room temperature,and also had good selection specificity,stability and repeatability.Through the investigation of the response mechanism of the device,it is confirmed that the composite Ti₃C₂-rGO as a sensitive material has more advantages in the adsorption of gas molecules,indicating that the Ti₃C₂-rGO composite material has potential application prospects in gas sensors,and it also provides a new method for designing gas sensors for testing at room temperature.In summary,the Ti₃C₂-rGO composite material we prepared shows a good application prospect in the non-invasive detection of diabetes.It not only provides an experimental basis for exploring Ti₃C₂-rGO composite materials in enzyme-based glucose sensors,but also enriches the understanding of glucose sensing mechanisms,and at the same time provides an experimental basis for the design of gas sensor devices working at room temperature.