Study On The Sensing Properties Of Graphene-based Gas Sensor

With the rapid development of modern society, as people gradually increase the awareness of environmental protection, the detection of toxic gases, and the monitoring of industrial waste gas have put forward higher requirements, which needs to study a novel gas sensor with high sensitivity and fast response. The sensing materials play an important role in the performances of gas sensors. Since the discovery of graphene in 2004, the unique two-dimensional structure is composed of a single layer of sp2 carbon atoms packed into a honeycomb lattice, its fascinating electrical, thermal and mechanical properties show great application prospects, the properties of large surface ratio, high carrier mobility and high signal to noise ratio make graphene anticipate in the field of gas sensor. Compared with common semiconductor metal oxide gas sensors with higher operating temperature, graphene can be carried out at room temperature for gas detection, however, the graphene gas sensor show low sensitivity, slow response and recovery in detecting gas, which limits the practical application of graphene. In order to solve the above problems, we study the sensitivity,response and recovery of graphene gas sensor, the main work includes:(1) We study the gas sensing properties of graphene by CVD method. Monolayer graphene was successfully prepared on copper substrate by atmospheric pressure chemical vapor deposition(APCVD) method, and transfer the graphene to the insulation substrate by direct contact transfer method in a simple and effective way, then make micro operation into sensor element Under the conditions of room temperature, we study the response of graphene to N02,NH3,andCO2. In the study of the gas sensing properties of CO2, after the transfer of graphene, we make it in carbon dioxide environment for drying treatment, compared to the graphene without CO2 gas treatment, the sensitivity of the gas is improved, and main reason is analyzed briefly.(2) We study the gas sensing properties of graphene oxide(rGO).Using hydrothermal synthesis method to prepare reduced graphene oxide-tungsten oxide(rGO-WO3),and the XRD, Raman, and SEM characterization prove that the material was successfully synthesized. On the performance test of gas sensitivity, under the conditions of room temperature, rGO-WO3 nano composite material gas sensor is better than rGO gas sensor towards to NH3, including higher response sensitivity, faster response and recovery, this is due to the reduced graphene oxide surface loaded of tungsten oxide particles, improving the surface properties of graphene, increasing the types and quantities of the active site of graphene surface, further regulating the electron transport capacity in graphene, enhancing the sensing properties.