▎ 摘　　要

Ammonia sensing behavior of graphene synthesized by a chemical vapor deposition on a copper substrate using a methane and hydrogen gas mixture has been investigated. The Raman spectroscopy is used to monitor the quality of graphene films transferred onto SiO2/Si substrates. The sensitivity and the recovery time of the device are enhanced by the decoration of platinum nanoparticles on the surface of graphene. The effects of the operating temperature on the sensing response have been studied. The adsorption and desorption curves have been analyzed using Langmuir kinetic theory for the adsorption of ammonia, and the influence of surface inhomogeneity was analyzed by Freundlich isotherm. The activation energy of adsorption and the heat of adsorption estimated from the above theories indicate that the platinum decorated surface has two different adsorption sites whereas bare graphene has only one adsorption site. This effect caused 80%-85% enhancement of sensor response for platinum decorated surface compared with the bare graphene surface throughout the measured temperature range for ammonia concentrations of 15-58 ppm. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4714552]