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.%在蓝宝石衬底上,利用PECVD在相对较低的温度和相对短的时间制备石墨烯.实验发现,在950℃,生长15 min,可制备纳米晶石墨烯.所制备的石墨烯为双层结构,存在较多的缺陷,使得其适合用于制作气敏传感器.制作的纳米晶石墨烯气敏传感器对甲醛气体显示出良好的响应和恢复特性.分析发现纳米晶石墨烯中大量的晶界和褶皱使气体的吸附和解吸附能垒降低是其表现出良好气敏特性的主要原因.
展开▼
