With the widespread adoption of communication technology, the potential hazards of electromagnetic (EM) radiation to human health and electronic devices operation have also emerged. Therefore, microwave absorption (MA) materials are becoming increasingly vital in the current electronic information age. Currently, extensive researches have been conducted on the MA mechanisms and optimized strategies, leading to significant advancements in improving MA performance. However, there is a lack of systematic summary of various innovative engineering strategies from nano-micro scale to metamaterial. Typically, nano-micro engineering techniques readily introduce heterointerfaces, components, or defects, etc. to boost dielectric loss and/or magnetic loss. And macroscopic strategy focuses on crafting more porous three-dimensional structures (foams, aerogels, films, etc.), which are beneficial for fine-tuning intrinsic impedance and triggering multiple reflections/scattering of EM wave (EMW). While metamaterial design featuring periodic layouts and sub-wavelength scales can also lead to energy loss via EMW resonances. Hence, in this review, we aim to provide a detailed overview of various engineering strategies for enhancing MA performance from nano-micro engineering to macroscopic strategies to metamaterial design. Furthermore, we elaborate the present challenges faced by MA technology and discuss potential future development opportunities and trends. It is our hope that this paper will offer insights and direction for the ongoing improvement of MA performance and achieving practical applications.

Modulation of metal sites coordination can significantly refine the electronic architecture of catalysts, thereby improving their catalytic performance. This work successfully developed a core–shell Co@N-doped porous carbon (Co@NC) catalyst by pyrolyzing the COF/MOF (IISERP-COF3/ZIF-67) composite in an inert atmosphere. The Co@NC catalyst exhibited impressive oxygen evolution reaction (OER) performance, with a small overpotential of 304 mV and a modest Tafel slope of 88.6 mV·dec⁻¹ in a 1 M KOH, alongside remarkable stability, maintaining 98.5% of its activity over 13 h. The role of IISERP-COF3 was pivotal in preventing Co atom aggregation during the ZIF-67 pyrolysis, which facilitated the creation of mesopores for enhanced mass transport and conductivity. Moreover, it effectively modulated the Co-N coordination to fine-tune the electronic structure, thereby optimizing the catalyst's capacity for adsorption of intermediates and boosting its intrinsic activity. Density functional theory (DFT) studies corroborate that the exceptional OER efficiency of Co@NC can be linked to the enhanced Co-N coordination, optimizing the localized electronic structure at the Co active sites. This study not only proposes an innovative approach for optimizing COF/MOF as effective electrocatalysts but also clears the path for the emergence of affordable, high-performance alternatives to precious metal-based catalysts, marking a significant advancement in sustainable energy technologies.

To adapt the practical demand, designing and constructing the multifunctional microwave absorbers (MAs) is the key future direction of research and development. However, effective integrating the multiple functions into a single material remains a huge challenge. Herein, cellular carbon foams (CCFs) with different porous structures were elaborately designed and fabricated in high efficiency through a facile continuous freeze-drying and carbonization processes using a sustainable biomass chitosan as the precursor. The obtained results revealed that the thermal treated temperature and g-C₃N₄ amount played a great impact on the carbonization degrees, pore sizes, and morphologies of CCFs, which led to their tunable electromagnetic (EM) parameters, improved conduction loss, and polarization loss abilities. Owing to the special cellular structure, the designed CCFs samples simultaneously displayed the strong absorption capabilities, broad absorption bandwidths, and thin matching thicknesses. Meanwhile, the as-prepared CCFs exhibited the strong hydrophobicity and good thermal insulation, endowing its attractive functions of self-cleaning and thermal insulation. Therefore, our findings not only presented a facile approach to produce different porous structures of CCFs, but also provided an effective strategy to develop multifunctional high-performance MAs on basis of three-dimensional CCFs.

Due to the good manipulation of electronic structure and defect, anion regulating should be a promising strategy to regulate the electromagnetic (EM) parameters and optimize the EM wave absorption performances (EMWAPs). In this work, we proposed a facile route for the large-scale production of core@shell structured hollow carbon spheres@MoS_xSe_2−x (x = 0.2, 0.6, and 1.0) multicomponent nanocomposites (MCNCs) through a mild template method followed by hydrothermal process. The obtained results revealed that the designed hollow carbon spheres@MoS_xSe_2−x MCNCs presented the improved sulfur vacancy concentration by regulating the x value from 0.2 to 1.0. The obtained hollow carbon spheres@MoS_xSe_2−x MCNCs displayed the extraordinary comprehensive EMWAPs because of the introduced abundant defects and excellent interfacial effects. Furthermore, the as-prepared hollow carbon spheres@MoS_xSe_2−x MCNCs presented the progressively improved comprehensive EMWAPs with the x value increasing from 0.2 to 1.0, which could be explained by their boosted polarization loss abilities and impedance matching characteristics originating from the enhanced sulfur vacancy concentration. Therefore, our findings not only demonstrated that the anion regulating was a promising method to optimize EM parameters and EMWAPs, but also provided a facile route to design the transition metal dichalcogenides-based MCNCs as the much more attractive candidates for high-performance microwave absorbers.

All inorganic CsPbI₃ perovskite solar cells (PSCs) have emerged as disruptive photovoltaic technology owing to their admirable photoelectric properties and the non-volatile active layer. However, the phase instability against moisture severely limits the fabrication environment for the high-efficiency devices, breaking through the confinement region to achieve scalable manufacturing has been the primary issue for future commercialization. Here, we develop a curing-anti-solvent strategy for fabricating high-quality and stable black-phase CsPbI₃ perovskite films in ambient air by introducing an inorganic polymer perhydropolysilazane (PHPS) into methyl acetate to form anti-template agent. The cross-linked PHPS reduces moisture erosions while the hydrolyzate silanol network (–Si(OH)₄–) controls the perovskite crystal growth by forming Lewis adducts with PbI₂ during the fabrication. The polycondensation adduct of Si–O–Si/Si–O–Pb strongly binds to CsPbI₃ grains as a shield layer to hamper phase transition. Using the inorganic CsPbI₃ perovskite thin-film with PHPS-modified anti-solvent processing as the light absorber, the n–i–p planar solar cell achieved an efficiency of 19.17% under standard illumination test conditions. More importantly, the devices showed excellent moisture stability, retaining about 90% of the initial efficiency after 1000 h under 30% RH.

Defect and interface engineering are efficient approaches to adjust the physical and chemical properties of nanomaterials. In order to effectively utilize these strategies for the improvement of microwave absorption properties (MAPs), in this study, we reported the synthesis of hollow carbon shells and hollow carbon@MoS₂ nanocomposites by the template-etching and template-etching-hydrothermal methods, respectively. The obtained results indicated that the degree of defect for hollow carbon shells and hollow carbon@MoS₂ could be modulated by the thickness of hollow carbon shell, which effectively fulfilled the optimization of electromagnetic parameters and improvement of MAPs. Furthermore, the microstructure investigations revealed that the precursor of hollow carbon shells was encapsulated by the sheet-like MoS₂ in high efficiency. And the introduction of MoS₂ nanosheets acting as the shell effectively improved the interfacial effects and boosted the polarization loss capabilities, which resulted in the improvement of comprehensive MAPs. The elaborately designed hollow carbon@MoS₂ samples displayed very outstanding MAPs including strong absorption capabilities, broad absorption bandwidth, and thin matching thicknesses. Therefore, this work provided a viable strategy to improve the MAPs of microwave absorbers by taking full advantage of their defect and interface engineering.

In order to effectively utilize the magnetic-dielectric synergy and interfacial engineering, in this paper, yolk–shell structured magnetic multicomponent nanocomposites (MCNCs) including CoNi@void@C and CoNi@void@C@MoS₂ were produced in large scale by in-situ pyrolysis of cubic CoNi Prussian blue analogs (PBAs) followed by the hydrothermal process, respectively. Because of their unique structures, excellent synergistic effect between dielectric and magnetic loss, the as-prepared CoNi@void@C and CoNi@void@C@MoS₂ MCNCs displayed very outstanding electromagnetic wave absorption performances (EMWAPs) including strong absorption capabilities, broad absorption bandwidth and thin matching thicknesses. Furthermore, the as-prepared CoNi@void@C and CoNi@void@C@MoS₂ MCNCs well maintained the cubic configuration of CoNi PBAs even after the thermal treatment and hydrothermal processes. The unique structure and formed carbon layers effectively prevented the corrosion of internal CoNi alloy during the formation of MoS₂, and CoNi@void@C@MoS₂ MCNCs with different MoS₂ contents could be synthesized by controlling the hydrothermal temperature. The obtained results revealed that the EM parameters, dielectric and magnetic loss capabilities of CoNi@void@C@MoS₂ MCNCs could be tuned by controlling hydrothermal temperature and filler loading, which made their outstanding EMWAPs could be achieved in different frequency regions. Taking account of simple process, low density and high chemical stability, our findings provided a new and effective pathway to develop the strong wideband microwave absorbers.