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

Abstract

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.