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Improving the interfacial impedance matching and attenuation ability of a microwave absorber is an important strategy to obtain excellent microwave absorbing performance. Here, we prepared an ultralight, hierarchical porous single-atom Co–N–C microwave absorber, in which evenly distributed single-atom Co is anchored in a porous N-doped carbon framework by N–Co bond via a facile bio-inspired method. These doped single atoms provide abundant highly active atomic absorption sites on the carbon skeleton, and considerable defects including pyridinic-N, pyrrolic-N, oxidized N, and so forth are introduced into the carbon framework owing to single Co atom doping. These doped single Co atoms and introduced defects act together as strong dipolar/interfacial polarization units, which lead to better impedance matching and a significant increase in attenuation capability of the absorber. The metal Co exists in form of a single atom, benefiting light weight of the absorber. Therefore, an extremely strong reflection loss (RL) value of − 60.9 dB is achieved at a lower filler content of 10 wt% with the absorber thickness of 2.5 mm, and the effective frequency bandwidth covered from 10.4 to 15.1 GHz with a thickness of 2.0 mm at a low filler content of 10 wt%. This research offers a novel route for designing a microwave absorber to improve microwave absorption performance and is expected to a wider range of absorbing materials with different structures.

Ferroelectric polymers are the mainstay of advanced flexible electronic devices. How to tailor the ferroelectric polymer films for various applications via simple processing approaches is challenging. Here we demonstrate the tuning of ferroelectric responses can be achieved in polymer blends of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) and polymethyl methacrylate (PMMA) prepared via a simple two-step process. The proposed two-step process endows the polymer blends with a random distribution of P(VDF-TrFE) crystalline phase, hence decoupling the coherent ferroelectric domain interactions between continuous ordered crystalline phases that ubiquitously existed in common P(VDF-TrFE) film. The incorporation of the miscible non-crystalline PMMA chains with low-polarity results in reversal dipoles and a transition from ferroelectric to antiferroelectric-like behavior, overcoming the trade-off between the polarization and depolarization fields. In particular, resultant excellent mechanical and electrical properties of the polymer blend films give rise to remarkably improved breakdown strength and energy storage performance, surpassing P(VDF-TrFE) and commercial biaxial-oriented polypropylene films. This work provides a simple and effective strategy to tailor the ferroelectric response of polymeric materials with great potential for flexible electrical energy storage applications.

The present work demonstrated the tunable negative permittivity and permeability properties of a two-phase composite material consisting of conductive matrix [polyaniline (PANI)] and magnetic filler [yttrium iron garnet (YIG)]. The negative permittivity observed in the YIG/PANI composites is accompanied by the formation of conductive PANI network, which induced the plasma oscillation of carriers in PANI obeying the Drude model. Through theoretical calculation, negative permeability can be realized and further adjusted by external magnetic field via the domain wall and spin resonances of YIG.

An excellent ternary composite photocatalyst consisting of silver orthophosphate (Ag3PO4), attapulgite (ATP), and TiO2 was synthesized, in which heterojunction was formed between dissimilar semiconductors to promote the separation of photo-generated charges. The ATP/TiO2/Ag3PO4 composite was characterized by SEM, XRD, and UV-vis diffuse reflectance spectroscopy. The co-deposition of Ag3PO4 and TiO2 nanoparticles onto the surface of ATP forms a lath-particle structure. Compared with composite photocatalysts consisting of two phases, ATP/TiO2/Ag3PO4 ternary composite exhibits greatly improved photocatalytic activity for degradation of rhodamine B under simulated solar irradiation. Such ternary composite not only improves the stability of Ag3PO4, but also lowers the cost by reducing application amount of Ag3PO4, which provides guidance for the design of Ag3PO4- and Ag-based composites for photocatalytic applications.