Supramolecular Fabrication And Gas/Humidity Sensing Properties Of Graphene-based Gas Sensors

With the continuous advancement of economic globalization and industrialization,the comprehensive performance of sensors have attracted great attention due to their extensive market demand and potential application in various fields.However,the poor stability and dissatisfied selectivity of sensor materials are two major problems that restrict their development.Therefore,the key challenge is conquering two major problems for fabricating a highly sensitive and selective sensing materials,which lays the foundation and guarantee for the preparation of high-performance sensors.As we all known,graphene is a p-type semiconductor.It have been considered as promising materials for gas sensing applications due to its unique and outstanding characteristics such as high surface area,excellent electrical conductivity.However,pristine graphene materials usually exhibit unsatisfactory gas-sensing properties.It is known that such properties of graphene can be tailored through non-covalent bonded chemical modifications and then efficiently enhance the electrical conductivity.Based on the above mentioned idea,this study reports the fabrication of high-performance graphene-based gas/humidity sensing materials that is based on different functional molecules supramolecular modification of graphene.?1?Here,the D-?-A molecule 4-aminoquinoline and 4-hydroxyquinoline supramolecularly assembled on the graphene through strong?-?stacking interaction.The gas-sensing experiments and density functional theory analysis show that the larger dipole moment modified graphene exhibits superior selectivity.The 4AQ-r GO sensing material exhibits fast response towards 10 ppm NO₂ within 200 s and the prepared supramolecular assembly exhibited an outstanding linear response over the large concentration range from 1 ppm to 10ppm.Hence,the obtained results demonstrate that the prepared supramolecular assembly holds great potential in the fabrication of efficient and effective low-concentration NO₂ gas sensors for practical applications.?2?On the basis of previous studies,the response time of the 4HQ-rGO/Cu²⁺sensor is 5 s and the recovery time is 6 s,and it has excellent recoverability,superior reversibility and outstanding selectivity.Based on such facts,herein,we report the formation of novel graphene based supramolecular assembly of 4-hydroxyquinoline modified reduced graphene oxide?4HQ-rGO?for acetic acid sensing.To increase the response time and recovery time,copper catalysts were introduced copper?II?ions could be promising candidates to enhance the charge transfer capability of materials.?3?The facile one-step supramolecular assembly method is adopted to modify reduced graphene oxide?rGO?with strong electron-withdrawing groups functional organic molecule pyranine for achieving comprehensive humidity sensing performance.The fabricated humidity sensor based on pyranine modified-reduced graphene oxide?Pyr-rGO?exhibits excellent sensing performance with ultrafast?2 s?,ultrahigh response?IL/IH=6000?and super good repeatability.The prepare Pyr-rGO provides a new insight into developing novel functional humidity sensing materials with enhanced device performance.