Graphene is ideal filler in nanocomposites due to its unique mechanical, electrical and thermal properties. However, it is challenging to uniformly distribute the large fraction of graphene fillers into a polymer matrix because graphene is not easily functionalized. We report a novel method to introduce a large fraction of graphene into a styrene–butadiene rubber (SBR) matrix. The obtained graphene/rubber nanocomposites were mechanically enhanced, acoustically absorptive under water, and electrically and thermally conductive. The Young's modulus of the nanocomposites was enhanced by over 30 times over that for rubber. The electrical conductivity of nanocomposites was ≤219 S m⁻¹ with 15% volume fraction of graphene content, and exhibited remarkable electromagnetic shielding efficiency of 45 dB at 8–12 GHz. The thermal conductivity of the nanocomposites was ≤2.922 W m⁻¹ k⁻¹, which was superior to the values of thermally conductive silicone rubber thermal interface materials. Moreover, the nanocomposites exhibited excellent underwater sound absorption (average absorption coefficient >0.8 at 6–30 kHz). Notably, the absorption performance of graphene/SBR nanocomposites increased with increasing water pressure. These multifunctional graphene/SBR nanocomposites have promising applications in electronics, thermal management and marine engineering.

A designable electromagnetic and acoustic double-shielding graphene-based metastructure exhibits not only excellent electromagnetic interference shielding property but also robust acoustic shielding efficiency.

The explode development of global automation and digitization brings increasing electromagnetic radiation, threatening information security and health. Biomass wave-absorbing materials stand out among massive absorbers due to their green and environmentally friendly features, yet remains severe challenge in equilibration between impedance matching and efficient loss ability. Herein, this work innovatively used waste bark which amounts up to 400 million cubic meters generated from forest as carbon precursor. The FeCo@C nanocomposites derived from FeCo-MOF precursor are introduced on the surface of bark-derived carbon pore using vacuum impregnation and carbonization methods, and tree bark-derived porous carbon (TPC)/FeCo@C composites are successfully fabricated. The unique hierarchical structure composed of three-dimensional (3D) parallel pore structure of bark-derived carbon and yolk-shell structure of FeCo@C favors to optimizing impedance matching and prolonging attenuation paths of microwaves. Additionally, the introduction of FeCo@C can promote interface polarization loss, as well as enhance synergistic effects of dielectric-magnetic losses. Multiple synergistic effects of structural coupling and dielectric-magnetic loss endow TPC/FeCo@C composite attractive absorbing ability. The optimized TPC/FeCo@C-5 exhibits a minimum reflection loss (RL_min) of − 61.04 dB and the effective bandwidth (EAB) of 7.25 GHz at a matching thickness of 2.64 mm, which is superior to most biomass-based absorbers. Apparently, this work presents a valuable concept for the secondary utilization of discarded bark in the domain of microwave absorption, which is significant for achieving energy saving and environmental protection and addressing electromagnetic pollution.