Lightweight 3D interconnected porous carbon with robust cavity skeleton derived from petroleum pitch for effective multi-band electromagnetic wave absorption

Ingenious porous skeleton design is highly desired for advanced carbonaceous electromagnetic wave absorbers (EWAs) to address the issues of impedance mismatch and enhance attenuation ability. Herein, a controllable structure of petroleum pitch-derived coral-like 3D interconnected porous carbon (PC) framework is constructed in one step by a hard-template method. The well-designed air-filled 3D interconnected cavity structure provides ideal impedance matching for absorbers and facilitates the multiple scattering of electromagnetic waves, while continuous robust carbon skeleton exhibits a satisfied electrical conductivity (≈553 S/m), greatly boosting the electrical energy loss capability of PCs. Therefore, even under an ultralow filler loading of only 6 wt%, the corresponding minimum reflection loss (RL) values of multiple thicknesses are all below −20 dB in the range of 1.5–5.0 mm, and the strongest RL of PCs reaches −50.04 dB (matching thickness is 2.37 mm), the widest effective absorption bandwidth is up to 4.4 GHz. The overall performance outperforms most of previously reported carbon-based EWAs. This synthetic strategy presents a broad application prospect due to its simple preparation method and lost-cost raw materials, and provides a new route for the design of advanced lightweight absorbers from abundant inferior heavy oil. Lightweight 3D interconnected porous carbon material with robust cavities skeleton is prepared by a facile template method and yields excellent multi-band electromagnetic wave absorption at an ultralow filler loading. • 3D porous carbon framework with robust cavity skeleton is prepared by a facile salt template strategy. • 3D interconnected cavity structure endows porous carbon with strong conduction loss and excellent impedance matching. • Porous carbon yields a high electromagnetic wave absorption property (−50.04 dB) at an ultralow filler loading of 6 wt%. • Highly-efficient multi-band electromagnetic wave absorption has been achieved by simply tuning the thickness. • This work offers a new route for the design of advanced carbon-based absorbers from low-cost petroleum pitch.