A Hierarchical 3D Graphene Nanocomposite Foam for Extremely Tough, Non‐Wettable, and Elastic Conductor

Abstract Recently, stretchable conductors and electrodes with hierarchically 3D foams have been highlighted for the development of simple and cost‐effective systems with enhanced performance in sensors, absorbents, energy storage devices, medical devices, and catalysts. For better versatility, additional properties such as mechanical robustness, water repellency, and thermal resistance are required for stable operation in tough, dry/wet conditions. Herein, a novel strategy is reported to fabricate highly robust and large‐area foam‐type conductor with a multiscale 3D matrix of a graphene/polymer nanocomposite (GNC) using a nickel‐based template. The 3D foam conductor with hierarchically porous GNC structures presents excellent stretchability (<160%), water repellency (contact angle > 126°), fire retardancy (>400 °C), and shock‐absorbing ability (>300 kPa), enabling potential application as versatile conductors working under extreme environments. In addition, it is demonstrated that the 3D GNC foam conductor can be used for healthcare electrode operating in wet environments under mechanical bending strain. It is believed that this work overcomes the lack of versatility of conventional bulk or 3D conductive polymer composites and can pave the way for the development of high‐performance, tough, and non‐wettable conductor that can operate under extreme environments.