Two-way actuation of graphene oxide arising from quantum mechanical effects

Using density functional theory (DFT) calculations, two stable phases were found for several graphene oxide (GO) crystals with linearly aligned epoxy groups. Upon electron injection, they exhibit two-way actuation behavior. This two-way actuation is named by the observations that one piece of monolayer GO crystal is able to expand or contract upon electron injection, namely, contraction of the stable phase, and expansion of the meta-stable phase. The obtained maximum in-plane strains are as high as 8% and −5%. Such large deformation in opposite directions obtained from a single piece GO material offers unique opportunities in designing highly tunable and integrated actuators for microelectromechanical or nanoelectromechanical systems.