  van der Waals (vdW) interaction plays a fundamental role in the
surface-molecules related phenomena. Tuning of the correlated charge
fluctuation in the vdW complex is a plausible way to modulate the molecules
interaction at the atomic surface. We report vdW interaction tunability of the
graphene-CO$_2$ complex by combining the first principle calculations with the
vdW exchange correlation density functionals and the time evaluation
measurements of CO$_2$ molecules adsorption/desorption on graphene under an
external electric field. The field-dependent charge transfer within the complex
unveils the controllable tuning of CO$_2$ from acceptor to donor. Meanwhile the
configuration of the adsorbed molecule - the equilibrium distance from graphene
and O-C-O bonding angle - is modified accordingly. The range of electrical
tunability is a unique feature for each type of molecules.
