Recyclable magnetic carbon foams possessing voltage-controllable electromagnetic shielding and oil/water separation

Lightweight carbon foams with high-performance electromagnetic interference (EMI) shielding have attracted extensive attentions. However, it is challenging for researchers to effectively regulate the EMI shielding of carbon foams independent on shield's thickness. Herein, we proposed a macroscopic magnetic carbon foams through a chemical engineering strategy under the synergies of nickel ion reduction and in-situ growth of carbon nanotubes on carbon frameworks derived from carbonized woods. The macroscopic magnetic carbon foams present high-performance EMI shielding with absorption-dominant mechanism, and the removal of oil pollutants for water purification. Magnetic properties favor the manipulation of oil absorption without direct mechanic contact. After burning, the magnetic carbon foams can be re-used in EMI shielding and oil absorbency. Furthermore, we used a novel electric voltage-driven strategy to upgrade EMI shielding performances of magnetic carbon foams. By the increase in applied voltages, the enhanced absorption-dominant EMI shielding and fast oil absorbency due to the decrease viscosity of crude oil could be simultaneously obtained. The strategy developed here may lead a new avenue toward the design of porous magnetic carbon foams with the enhanced voltage-driven multifunctionalities for practical applications.