Gas sensing properties of graphene synthesized by chemical vapor deposition

The gas sensing properties of graphene synthesized by a chemical vapor deposition (CVD) method are investigated. Synthesis of graphene is carried out on a copper substrate using a methane and hydrogen gas mixture by a CVD process at the atmospheric pressure. The graphene films are transferred to different substrates after wet etching of the copper substrates. The Raman spectra reveal that the graphene films made on SiO2/Si substrates are of high quality. The reflectance spectra of graphene were measured in UV/Visible region of the spectrum. Theoretically calculated reflectance spectra based on Fresnelʹs approach indicates that the CVD graphene has a single layer. The gas sensing properties of graphene were tested for different reducing gasses as a function of measurement temperature and gas concentration. It is found that the gas sensing characteristics such as response time, recovery time, and sensitivity depend on the target gas, gas concentration, test temperature, and the ambient gas composition. The cross sensitivity of few combinations of reducing gasses such as, NH3, CH4, and H2 was also investigated.