关键词: 石墨烯, 吸附, 膜, 测量, 甲醛, 曝气

Abstract:

Gas sensors play a significant role in the fields of environmental monitoring, industrial production, safety, medical diagnosis, military and aerospace. Solid state gas sensors possess advantages of small size, low power, high sensitivity and low cost. They can detect very low concentrations of a wide range of gases in the range of parts-per-million (mg·L^-1). Graphene is a promising material for solid state gas sensors with high sensitivity due to its high carrier mobility, maximum surface-to-volume ratio, and low noise level. In this work, nano-grain graphene is grown on sapphire substrate by plasma enhanced chemical vapor deposition at a relative low temperature at 950℃ and a short time of 15 min. The as-prepared graphene shows bilayer structure with large amount of defects, which brings advantages for graphene gas sensors. The nano-grain graphene gas sensor on sapphire shows good response and recovery characteristics for formaldehyde gas, and exhibits good sensitivity of 3% response toward a concentration of formaldehyde gas of 20 mg·L^-1 at room temperature with a response time of 9.92 min. The recovery time of the nano-grain graphene sensor for formaldehyde gas of 20 mg·L^-1 is 17 min. Low energy barrier of the gas adsorption and desorption induced by large numbers of grain boundaries and wrinkles in the nano-grain graphene is the main reason for its good gas sense characteristics.

Key words: graphene, adsorption, membranes, measurement, formaldehyde, aeration