Observation of Electrically Tunable van der Waals Interaction in Graphene-Molecule Complex

TL;DR

This study demonstrates that the van der Waals interaction between graphene and CO₂ molecules can be electrically tuned, affecting charge transfer and molecular configuration, which could enable controlled surface-molecule interactions.

Contribution

It provides the first combined theoretical and experimental evidence of electric field-controlled vdW interaction in graphene-molecule complexes.

Findings

Charge transfer can be switched from acceptor to donor with electric field.

Molecular configuration, including distance and bonding angle, is tunable by electric field.

The tunability range varies for different molecules.

Abstract

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.