Abstract
This study used a gold-nanoparticle-decorated graphene foam composite as a sensor for detecting low concentration ammonia gas. Few-layer graphene was grown on the nickel foam by CVD. Then the nickel foam was removed by a etching process to fabricate a three-dimensional graphene foam structure. Graphene foam was then adhered to a PET film to prevent the graphene foam structure from collapse during handling. Gold nanoparticles with different sizes were deposited on the surface of the graphene foam by sputtering. The results showed that the sensitivity, recovery time, and response time of the sensor were enhanced attributing to the deposition of gold nanoparticles on the surface of graphene foam. Size effects of gold nanoparticles on the performance of the sensor were studied and it was found that smaller gold nanoparticles enhance the sensitivity of the device significantly due to the increase of the specific surface area. In addition, the sensor possessing high sensitivity in the range of 50 to 1000 ppm for NH3 and having reversible behavior were detected. The dependence of the sensing ability in the operating temperature was also investigated. In high operating temperature, the ability of adsorption and desorption of the ammonia molecules was remarkable enhanced owing to the fully desorption of the NH3 at elevated temperature.