Graphene Synthesis and Application for Gas Sensor

학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2012. 2. 김용협.Gas sensing application of graphene utilizes a charge transfer from adsorbed molecules to graphene or a local electrostatic gating effect resulting in conductance change of graphene, which is quite similar to other solid-state gas sensors. However, graphene is a fascinating material for sensing due to its large specific surface area for molecular adsorption and outstanding electrical properties such as low noise level and high carrier mobility. In addition, an electrostatic gating effect by local depletion at active sites can be maximized due to the extremely thin thickness of graphene. In this paper, graphene was used as sensing material which was synthesized by chemical vapor deposition method. It can be transferred to any substrates in large scale with a single layer atomic thickness. As-grown graphene is appropriate material for sensor application due to outstanding electrical properties as well. In the present study, we report a simple and reproducible method to improve the sensing performance of a graphene gas sensor using ozone treatment and demonstrate it with nitrogen dioxide (NO2) gas. And we represent the fabrication and hydrogen sensing properties of palladium (Pd) decorated graphene sensor as well. Summarizing the essentials of this paper, we successfully fabricated the highly sensitive graphene gas sensor by surface modification. By controlling ozone treatment time, optimized density of the oxygen functional groups can be readily introduced on the graphene surface, leading to the remarkable enhancement of the NO2 sensing performances such as sensitivity, detection limit and response time. And, optimized density of the Pd nanoparticles by controlling the deposition thickness improved the sensitivity of the hydrogen sensor.Maste