▎ 摘　　要

Understanding the influences of defect states on gas adsorption on graphene is at the heart of developing graphene based gas sensors for practical applications. However, it has been challenging to experimentally discriminate the gas adsorptions induced by the defects on graphene, especially the charged impurities commonly found on the transferred graphene samples. Here, using a graphene transistor biased with the quasistatic gate voltage, this study experimentally measures the charge density and the scattering strength of the gas adsorbents on graphene and directly resolves the defect-induced versus intrinsic gas adsorption processes on graphene for the first time. Furthermore, the elimination and the tuning of the defect-induced gas adsorptions on graphene are also demonstrated via the chemical compensation process and the gate voltage technique, respectively. These findings provide critical experimental proofs and a versatile platform for understanding and manipulating the defect-gas interactions on graphene, and could advance the developments of defect-free and label-free gas sensing applications using graphene transistors.