  We investigate the chemisorptions of oxygen molecules on bilayer graphene
(BLG) and its electrically modified charge-doping effect using conductivity
measurement of the field effect transistor channeled with BLG. We demonstrate
that the change of the Fermi level by manipulating the gate electric field
significantly affects not only the rate of molecular adsorption but also the
carrier-scattering strength of adsorbed molecules. Exploration of the charge
transfer kinetics reveals the electrochemical nature of the oxygen adsorption
on BLG. [This document is the unedited Author's version of a Submitted Work
that was subsequently accepted for publication in Nano Letters, {\copyright}
American Chemical Society after peer review. To access the final edited and
published work see http://dx.doi.org/10.1021/nl202002p.]
