Graphene-based Janus film with improved sensitive response capacity for smart actuators

A flexible graphene-based Janus film composed of two sides, a graphene oxides (GO) layer and a reduced GO (RGO) layer, has been successfully fabricated via sequential vacuum filtration, chemical reduction with hydroiodic acid (referred to as HI-reduction), and evaporation-induced self-assembly. The resultant GO/RGO Janus film exhibited excellent mechanical stability and rapid response to humidity and temperature, accompanied by reversible crimping and bending actuations. The Janus film rolled up on the short-side in response to moisture stimulation due to the hygroscopic expansion of the GO layer, while the film rolled up in the opposite direction under thermal stimulation, which occurred due to the negative thermal expansion of the RGO layer. The structure optimization provided the GO/RGO Janus film with an improved sensitive response capacity to intelligent actuating behavior, which could be triggered by a sweaty or warm hand. Since the obtained RGO layer created with HI-reduction exhibited favorable electrical conductivity, a smart perceptual switch based on the GO/RGO Janus film was developed to control a circuit and switch a bulb on/off triggered by the moist-air supply or a sweaty hand. (c) 2018 Elsevier B.V. All rights reserved.