Herein, a supermolecular‐scale cage‐confinement pyrolysis strategy is proposed to build two dielectric electromagnetic wave absorbents, in which MoO2 nanoparticles are sandwiched uniformly between porous carbon shells and reduced graphene oxide (RGO). Both sandwich structures are derived from hybrid hydrogels doped by two different crosslinkers (with/without oxygen bridge), which can precisely confine Mo source (e.g., PMo12). Without adding magnetic components, both absorbents exhibit excellent low frequency absorption performance in combination with electrically tunable ability and enhanced reflection loss value, which is superior over other relative 2D dielectric absorbers and satisfies the requirements of portable electronics. Notably, introducing oxygen bridges in the crosslinker generates a more stable confining configuration, which in turn renders its corresponding derivative exhibiting an extra multifrequency electromagnetic wave absorption trait. The intrinsic electromagnetic wave adjustment mechanism of the ternary hybrid absorbent is also explored. The result reveals that the elevated electromagnetic wave absorbing property is attributed to moderate attenuation constant and glorious impendence matching. The cage‐confinement pyrolysis route to fabricate 2D MoO2‐based dielectric electromagnetic wave absorbents opens a new path for the design of electromagnetic wave absorbents used in multi/low frequency.

Porous three-dimensional SiC/melamine-derived carbon foam (3D-SiC/MDCF) composite with an original open pore structure was fabricated by the heat treatment of the commercial melamine foam (MF), carbonization of the stable MF, and chemical vapor deposition of the ultra-thin SiC coating. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to detect the microstructure and morphology of the as-prepared composites. The results indicated that the 3D-SiC/MDCF composites with the coating structure were prepared successfully. The obtained minimum reflection loss was-29.50 dB when the frequency and absorption thickness were 11.36 GHz and 1.75 mm, respectively. Further, a novel strategy was put forward to state that the best microwave absorption property with a thin thickness of 1.65 mm was gained, where the minimum reflection loss was-24.51 dB and the frequency bandwidth was 3.08 GHz. The excellent electromagnetic wave absorption ability resulted from the specific cladding structure, which could change the raw dielectric property to acquire excellent impedance matching. This present work had a certain extend reference meaning for the potential applications of the lightweight wave absorption materials with target functionalities.

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Three underlying root causes for ultrahigh initial coulombic efficiency (99.4%) of Na-storage cobalt sulfide nanoarrays.