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Highlights NiCo-LDHs successfully grow in situ on rod-like ZnO with unique structures.The interface of NiCo@C and rod-like ZnO result in interfacial polarization.The RLmin of NiCo@C/ZnO reaches − 60.97 dB with the EABmax of 6.08 GHz.The excellent performance comes from the effect of dielectric loss and magnetic loss. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00704-5., Layered double hydroxides (LDHs) have a special structure and atom composition, which are expected to be an excellent electromagnetic wave (EMW) absorber. However, it is still a problem that obtaining excellent EMW-absorbing materials from LDHs. Herein, we designed heterostructure NiCo-LDHs@ZnO nanorod and then subsequent heat treating to derive NiCo@C/ZnO composites. Finally, with the synergy of excellent dielectric loss and magnetic loss, an outstanding absorption performance could be achieved with the reflection loss of − 60.97 dB at the matching thickness of 2.3 mm, and the widest absorption bandwidth of 6.08 GHz was realized at 2.0 mm. Moreover, this research work provides a reference for the development and utilization of LDHs materials in the field of microwave absorption materials and can also provide ideas for the design of layered structural absorbers. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00704-5.

In recent years, metal oxides, especially ZnO, have received extensive attention for non-enzyme biosensors. Au-ZnO composite nanofibers were prepared by one-pot electrospinning a dimethylformamide solution of chloroauric acid and zinc acetate containing polyacrylonitrile and polyvinylpyrrolidone followed by calcination. The morphology, composition, and crystal structure of the prepared Au-ZnO nanofibers were investigated by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction methods. The Au nanoparticles with a face-centered cubic structure were uniformly distributed on the fine ZnO nanofibers. The ZnO fiber with the diameter of 100 ± 20 nm consisted of hexagonal wurtzite structural ZnO particle. Compared to the individual ZnO sample, the presence of Au nanoparticles retains the fibrous structure and enhances the electrical conductivity of the fibers, proved by cyclic voltammetry and electrochemical impedance analysis. By fine-tuning the molar ratio of Au/Zn in the precursor solution, the morphology of Au-ZnO can be controlled. The Au-ZnO composite fiber was used as an enzyme-like catalyst for the sensitive detection of H2O2 based on synergetic catalytic effect of Au nanoparticles and ZnO. Au-ZnO electrode with the Au/Zn atomic ratio of 0.24 shows the highest activity for H2O2 reduction. There was a good linear relationship between catalytic current and H2O2 concentration in the range of 1 × 10−6–6 × 10−3 M (R2 = 0.9994). The detection limit is calculated to be 0.1 × 10−6 M (S/N>3). This Au-ZnO composite fiber can be used as a non-enzyme sensing material for the high sensitive and selective determination of H2O2.

The nitrogen-rich carbon nanotubes doped with well-dispersed fine silver nanoparticles (AgNPs-NCNTs) were fabricated by carbonization of the silver-polydopamine (AgNPs-PDA) multilayers. The wall thickness of the nanotube is tunable by varying the numbers of the layer-by-layer alternate deposition of Ag and PDA on electrospun polystyrene (PS) fibers. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrate the tunable tubular structure by various AgNPs-PDA layers and the uniform distribution of fine silver nanoparticles with the size of about 6 nm in the nanotube. The composition of the nanocomposites was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrate that the electrochemical properties of AgNPs-NCNTs depend on the numbers of AgNPs-PDA layers. The composite material shows excellent electrocatalytic activity to H2O2 reduction, with a low limit of detection (LOD) of 0.03 μM (S/N ≥ 3) and a sensitivity of 1004.9 μA mM−1 cm−2. Meanwhile, the AgNPs-NCNTs present a high catalytic activity to O2 reduction reaction with near 4-electron transfer process. The related catalysis mechanisms were proposed and validated by rotating disk electrode and dissolved oxygen analysis. This catalyst shows high stability for oxygen reduction over 500 cycles.

Co/ZnO/Ti3C2Tx composites were successfully prepared by using metal organic framework (MOF) and two-dimensional titanium carbide composites as precursors via a simple self-assembly process and subsequent annealing treatment. The influence of carbonization temperature on microwave absorption properties was studied in detail. Multiple scattering and reflection and polarization behaviors produced by its unique laminated structure endow the material with excellent performance. When the annealing temperature was 750 °C, the best reflection loss value could reach −44.22 dB at 2.4 mm, and the maximum effective absorption bandwidth was 5.28 GHz at the thickness of 2.4 mm. The microwave absorption mechanism is attributed to dielectric loss, magnetic loss, multiple reflections and scattering. Therefore, Co/ZnO/Ti3C2Tx composites can be used as an idea choice for lightweight and efficient microwave absorbers.