Tuning Infrared Emissivity of Graphene Aerogel Through Ion Intercalation

Dynamically modulating the infrared emissivity of materials is of great importance in various applications (e.g., thermal camouflage and radiative cooling). Even though graphene-based materials (such as multilayer graphene, MLG) have shown great potential in active control of emissivity, the device lifetime is rather short, while low-cost large-scale production is difficult to achieve. Herein, graphene aerogels (GAs) with high porosity are prepared by a simple hydrothermal method, and used as electrode in an infrared emissivity modulator with a sandwiched structure. It is demonstrated that the emissivity of GA can be tuned through ion intercalation by electrostatic gating. The modulation depth of GA is comparable to that of MLG, but device lifetime is much longer. This is likely due to the porous structure of GA formed by a continuous three-dimensional MLG network, which makes it easier for ion transport, while allowing effective charge transfer from anions adsorbed on or intercalated into MLG to carbons. Due to a change in surface roughness of GA upon compressing, the emissivity of GA can be further tuned by compressive strain, which provides additional freedom in control of emissivity. The observations offer a promising avenue for the preparation of large-scale emissivity modulators at low cost, which is beneficial for practical applications.