Constructing interfaces in heterostructures is effective for modulating the electronic properties of electrocatalysts. The hollow CoMoO₄–Co₃O₄ heterostructure (HCMCH) was prepared as a bifunctional electrocatalyst for Li-O₂ battery. The different components in CoMoO₄–Co₃O₄ heterostructure presented the efficient coupling and enhanced the electrocatalytic activity for aprotic oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), in which it improved the obviously reduced overpotential of 300 mV (compared with the pure Ketjen black (KB) electrode), enhanced reversibility of 80% capacity retention after 6 full cycles and the superior cyclability of more than 200 cycles with an optimized strategy. The battery performance of the HCMCH was not only associated with the unique hollow structure and rich active sites but also with coupling interface constructions synergetic effects attaching to the improving conductivity and optimized the discharge conversion. These results suggested that this HCMCH electrocatalyst was a promising candidate for the Li-O₂ battery and it gave a novel insight for high performance electrocatalyst designing.

The escalating electromagnetic (EM) pollution issues and the demand to elevate military stealth technology make it imperative to develop cost-effective and high-performance electromagnetic wave (EMW) absorbing materials. In this paper, the flower-like CuS/γ-Fe₂O₃ van der Waals (vdW) heterostructures have been synthesized via a facile two-step solvothermal approach. The flower-like CuS skeleton increases the attenuation path of EMW while reducing the material density. Different contents of γ-Fe₂O₃ nanoparticles anchor between the flower-like CuS nanosheets to constitute a heterogeneous structure, which enables dielectric and magnetic loss synergistically to optimize impedance matching and remarkably improve the EMW absorption performance. The minimum reflection loss (RL_min) is −49.36 dB with a thickness of only 1.6 mm and the effective absorption bandwidth (EAB) reaches 4.64 GHz (13.36–18 GHz). By adjusting the thickness of the absorber, the EAB can cover 96% of the GHz band. Notably, the superior absorption of −61.53 dB at middle frequency band can be obtained by adjusting the amount of Fe₂O₃ addition. In this study, the adjustment of EM parameters and the optimization of impedance matching have been achieved by constructing a novel vdW heterogeneous structure, which provides fresh ideas and references for the design of high-performance EMW absorbing materials.

Electromagnetic wave absorption materials are widely used in electronic equipment and military fields. However, high cost and complex preparation processes become a major obstacle in promoting popularization in the civil field. To solve the problems above, researchers have made great efforts to develop Fe-based carbon composites. However, most of the typical composites require a high filling ratio while achieving excellent properties. Therefore, in this study, carbon nanofibers (CNFs) combined with the hollow rice-grained α-Fe₂O₃ nanoparticles were prepared by the in-situ transformation method. The rational microstructure design provided a solution for reducing the filling ratio, optimizing impedance matching, and improving electromagnetic wave absorption performance. The strong reflection loss value (−38.1 dB) and broad effective absorption bandwidth (4.6 GHz) for Fe₂O₃/CNFs composites were achieved with a low filling ratio (20 wt.%), and the analysis of electromagnetic parameters validated that the microstructure of Fe₂O₃/CNFs plays a crucial role in the performance improvement. With the optimized impedance matching and simple preparation method, Fe₂O₃/CNFs have broad application prospects in electromagnetic wave absorption.

Reasonably regulating electronic coupling to promote charge transfer and exciton separation has been regarded a promising approach in catalysis. The material engineering of van der Waals heterojunction (vdWsH) based on two-dimensional (2D) materials would be a potential way to optimize the as-prepared extrinsic physicochemical characteristics. However, it was still an almost uncultivated land waiting for exploration in catalysis. Herein, we introduced the inert h-boron nitride (h-BN) in non-metal reduced graphene oxide (GN) catalysts and constructed BN-GN vdWsH. The theoretical calculation demonstrated that the h-BN can effectively modify the electronic properties of graphene. With the introduction of h-BN, the BN-GN vdWsH can obviously enhance the catalytic activity of Li-CO₂ battery. The existence of BN-GN vdWsH can reduce the overpotential more than 700 mV compared with reduced graphene oxide during the CO₂ reduction reaction (CO₂RR) and CO₂ evolution reaction (CO₂ER), and it extended cyclic stability more than three times, which was one of the most outstanding non-metallic catalysts. The reasonable structure design made it work as a high efficient electrocatalyst, which shed light on the development for functional treatment of catalytic materials.