Transformation of 2D Flakes to 3D Hollow Bowls: Matthew Effect Enables Defects to Prevail in Electromagnetic Wave Absorption of Hollow rGO Bowls.

High-efficiency electromagnetic (EM) wave (EMW)-absorbing materials have attracted extensive scientific and technical interest. Although identifying the dominant EM loss mechanism in dielectric-loss materials is indispensable, it is challenging due to a complex synergism between dipole/interfacial polarization and conduction loss. Modulation of defects and microstructures can be a possible approach to determine the dominant EM loss mechanism and realize high-efficiency absorption. Herein, 2D reduced graphene oxide (rGO) flakes are integrated into a 3D hollow bowl-like structure, which increases defect sites (i.e., oxygen vacancy and lattice defect) and reduces the stacked thickness of rGO. Despite their lower stacked thicknesses, the hollow rGO bowls with more defects exhibit lower conductivities but higher permittivities. Accompanied by the transformation from 2D flakes to 3D hollow bowls, the dominant EM loss mechanism of rGO transforms from conduction loss to defect-induced polarization. Furthermore, the defect engineering and structural design endow rGO with well-matched impedance and strong EMW-absorbing capacity. A minimum reflection loss of -41.6 dB (1.3 mm) and an effective absorption bandwidth of 4.8 GHz (1.5 mm) is achieved at a filler loading of 5 wt%. This study will provide meaningful insights into the development of materials with superior EMW-absorbing performances via defect engineering and structural design.

Controllable Synthesis of Highly Symmetrical Streamlined Structure for Wideband Microwave Absorption.

Highly symmetrical and streamlined nanostructures possessing unique electron scattering, electron-phonon coupling, and electron confinement characteristics have attracted a lot of attention. However, the controllable synthesis of such a nanostructure with regulated shapes and sizes remains a huge challenge. In this work, a peanut-like MnO@C structure, assembled by two core-shell nanosphere is developed via a facile hydrogen ion concentration regulation strategy. Off-axis electron holography technique, charge reconstruction, and COMSOL Multiphysics simulation jointly reveal the unique electronic distribution and confirm its higher dielectric sensitive ability, which can be used as microwave absorption to deal with currently electromagnetic pollution. The results reveal that the peanut-like core-shell MnO@C exhibits great wideband properties with effective absorption bandwidth of 6.6 GHz, covering 10.8-17.2 GHz band. Inspired by this structure-induced sensitively dielectric behavior, promoting the development of symmetrical and streamlined nanostructure would be attractive for many other promising applications in the future, such as piezoelectric material and supercapacitor and electromagnetic shielding.

Exceptionally Bifunctional ORR/OER Performance via Synergistic Atom-Cluster Interaction.

The single-atom sites (SAs) have achieved enhanced performance toward oxygen reduction reaction (ORR) with the effective utilization of the active sites. However, the excess adsorption of the intermediates and the limited stability hinders performance improvement. Metal clusters with promising stability and weak adsorption can be used as potential substitutions, but the lack of active sites is considered undesirable for catalytic reactions. Herein, a framework of Fe nanoclusters combined with SAs on One dimensional (1D) carbon nanotubes (Fe3 C-NCNTs 90 min CC-1 ) is synthesized to confirm the synergistic atom-cluster interaction. The composite exhibits strong polarization and electron redistribution between nanocluster and SAs. The electron redistribution will significantly boost the electron transport and the desorption of the intermediates, which is confirmed by off-axis holography and DFT calculation. The electrocatalytic performance is significantly enhanced as the half-wave potential of ORR increased 75 mV and the potential of OER increased 133 mV compared with the sample without nanoclusters. Furthermore, such a bifunctional catalyst endows homemade Zn-air batteries (ZABs) with high power density and long-term stability. This work paves a facile route to design bifunctional ORR/OER electrocatalysts consisting of 0D composite structures.

Visualizing Nanoscale Interlayer Magnetic Interactions and Unconventional Low-Frequency Behaviors in Ferromagnetic Multishelled Structures.

Precise manipulation of van der Waals forces within 2D atomic layers allows for exact control over electron-phonon coupling, leading to the exceptional quantum properties. However, applying this technique to diverse structures such as 3D materials is challenging. Therefore, investigating new hierarchical structures and different interlayer forces is crucial for overcoming these limitations and discovering novel physical properties. In this work, a multishelled ferromagnetic material with controllable shell numbers is developed. By strategically regulating the magnetic interactions between these shells, the magnetic properties of each shell are fine-tuned. This approach reveals distinctive magnetic characteristics including regulated magnetic domain configurations and enhanced effective fields. The nanoscale magnetic interactions between the shells are observed and analyzed, which shed light on the modified magnetic properties of each shell, enhancing the understanding and control of ferromagnetic materials. The distinctive magnetic interaction significantly boosts electromagnetic absorption at low-frequency frequencies used by fifth-generation wireless devices, outperforming ferromagnetic materials without multilayer structures by several folds. The application of magnetic interactions in materials science reveals thrilling prospects for technological and electronic innovation.

Mixed-Dimensional Assembly Strategy to Construct Reduced Graphene Oxide/Carbon Foams Heterostructures for Microwave Absorption, Anti-Corrosion and Thermal Insulation.

Considering the serious electromagnetic wave (EMW) pollution problems and complex application condition, there is a pressing need to amalgamate multiple functionalities within a single substance. However, the effective integration of diverse functions into designed EMW absorption materials still faces the huge challenges. Herein, reduced graphene oxide/carbon foams (RGO/CFs) with two-dimensional/three-dimensional (2D/3D) van der Waals (vdWs) heterostructures were meticulously engineered and synthesized utilizing an efficient methodology involving freeze-drying, immersing absorption, secondary freeze-drying, followed by carbonization treatment. Thanks to their excellent linkage effect of amplified dielectric loss and optimized impedance matching, the designed 2D/3D RGO/CFs vdWs heterostructures demonstrated commendable EMW absorption performances, achieving a broad absorption bandwidth of 6.2 GHz and a reflection loss of - 50.58 dB with the low matching thicknesses. Furthermore, the obtained 2D/3D RGO/CFs vdWs heterostructures also displayed the significant radar stealth properties, good corrosion resistance performances as well as outstanding thermal insulation capabilities, displaying the great potential in complex and variable environments. Accordingly, this work not only demonstrated a straightforward method for fabricating 2D/3D vdWs heterostructures, but also outlined a powerful mixed-dimensional assembly strategy for engineering multifunctional foams for electromagnetic protection, aerospace and other complex conditions.

Distinct skyrmion phases at room temperature in two-dimensional ferromagnet Fe3GaTe2.

Distinct skyrmion phases at room temperature hosted by one material offer additional degree of freedom for the design of topology-based compact and energetically-efficient spintronic devices. The field has been extended to low-dimensional magnets with the discovery of magnetism in two-dimensional van der Waals magnets. However, creating multiple skyrmion phases in 2D magnets, especially above room temperature, remains a major challenge. Here, we report the experimental observation of mixed-type skyrmions, exhibiting both Bloch and hybrid characteristics, in a room-temperature ferromagnet Fe3GaTe2. Analysis of the magnetic intensities under varied imaging conditions coupled with complementary simulations reveal that spontaneous Bloch skyrmions exist as the magnetic ground state with the coexistence of hybrid stripes domain, on account of the interplay between the dipolar interaction and the Dzyaloshinskii-Moriya interaction. Moreover, hybrid skyrmions are created and their coexisting phases with Bloch skyrmions exhibit considerably high thermostability, enduring up to 328 K. The findings open perspectives for 2D spintronic devices incorporating distinct skyrmion phases at room temperature.

Functional nanoporous graphene superlattice.

Two-dimensional (2D) superlattices, formed by stacking sublattices of 2D materials, have emerged as a powerful platform for tailoring and enhancing material properties beyond their intrinsic characteristics. However, conventional synthesis methods are limited to pristine 2D material sublattices, posing a significant practical challenge when it comes to stacking chemically modified sublattices. Here we report a chemical synthesis method that overcomes this challenge by creating a unique 2D graphene superlattice, stacking graphene sublattices with monodisperse, nanometer-sized, square-shaped pores and strategically doped elements at the pore edges. The resulting graphene superlattice exhibits remarkable correlations between quantum phases at both the electron and phonon levels, leading to diverse functionalities, such as electromagnetic shielding, energy harvesting, optoelectronics, and thermoelectrics. Overall, our findings not only provide chemical design principles for synthesizing and understanding functional 2D superlattices but also expand their enhanced functionality and extensive application potential compared to their pristine counterparts.

Self-Healing Liquid Metal Magnetic Hydrogels for Smart Feedback Sensors and High-Performance Electromagnetic Shielding.

Hydrogels exhibit potential applications in smart wearable devices because of their exceptional sensitivity to various external stimuli. However, their applications are limited by challenges in terms of issues in biocompatibility, custom shape, and self-healing. Herein, a conductive, stretchable, adaptable, self-healing, and biocompatible liquid metal GaInSn/Ni-based composite hydrogel is developed by incorporating a magnetic liquid metal into the hydrogel framework through crosslinking polyvinyl alcohol (PVA) with sodium tetraborate. The excellent stretchability and fast self-healing capability of the PVA/liquid metal hydrogel are derived from its abundant hydrogen binding sites and liquid metal fusion. Significantly, owing to the magnetic constituent, the PVA/liquid metal hydrogel can be guided remotely using an external magnetic field to a specific position to repair the broken wires with no need for manual operation. The composite hydrogel also exhibits sensitive deformation responses and can be used as a strain sensor to monitor various body motions. Additionally, the multifunctional hydrogel displays absorption-dominated electromagnetic interference (EMI) shielding properties. The total shielding performance of the composite hydrogel increases to ~ 62.5 dB from ~ 31.8 dB of the pure PVA hydrogel at the thickness of 3.0 mm. The proposed bioinspired multifunctional magnetic hydrogel demonstrates substantial application potential in the field of intelligent wearable devices.

Staggered circular nanoporous graphene converts electromagnetic waves into electricity.

Harvesting largely ignored and wasted electromagnetic (EM) energy released by electronic devices and converting it into direct current (DC) electricity is an attractive strategy not only to reduce EM pollution but also address the ever-increasing energy crisis. Here we report the synthesis of nanoparticle-templated graphene with monodisperse and staggered circular nanopores enabling an EM-heat-DC conversion pathway. We experimentally and theoretically demonstrate that this staggered nanoporous structure alters graphene's electronic and phononic properties by synergistically manipulating its intralayer nanostructures and interlayer interactions. The staggered circular nanoporous graphene exhibits an anomalous combination of properties, which lead to an efficient absorption and conversion of EM waves into heat and in turn an output of DC electricity through the thermoelectric effect. Overall, our results advance the fundamental understanding of the structure-property relationships of ordered nanoporous graphene, providing an effective strategy to reduce EM pollution and generate electric energy.

One-Dimensional Magnetic FeCoNi Alloy Toward Low-Frequency Electromagnetic Wave Absorption.

Rational designing of one-dimensional (1D) magnetic alloy to facilitate electromagnetic (EM) wave attenuation capability in low-frequency (2-6 GHz) microwave absorption field is highly desired but remains a significant challenge. In this study, a composite EM wave absorber made of a FeCoNi medium-entropy alloy embedded in a 1D carbon matrix framework is rationally designed through an improved electrospinning method. The 1D-shaped FeCoNi alloy embedded composite demonstrates the high-density and continuous magnetic network using off-axis electronic holography technique, indicating the excellent magnetic loss ability under an external EM field. Then, the in-depth analysis shows that many factors, including 1D anisotropy and intrinsic physical features of the magnetic medium-entropy alloy, primarily contribute to the enhanced EM wave absorption performance. Therefore, the fabricated EM wave absorber shows an increasing effective absorption band of 1.3 GHz in the low-frequency electromagnetic field at an ultrathin thickness of 2 mm. Thus, this study opens up a new method for the design and preparation of high-performance 1D magnetic EM absorbers.

Effects of Juhongtanke oral solution on alleviating the symptoms of community-acquired pneumonia: A multicenter, prospective, randomized controlled trial.

Introduction: The timely alleviation of symptoms is essential for managing community-acquired pneumonia (CAP). Juhongtanke oral solution is a traditional marketed Chinese patent medicine believed to ease CAP symptoms. The currently available evidence is based on a few retrospective studies of patients with various types of pneumonia, whereas robust randomized controlled trials (RCTs) that support this notion are lacking. Material and methods: In this multi-center, prospective RCT, patients were randomly allocated to receive routine treatment alone or a combination of Juhongtanke oral solution (20 mL q8h) for 5 days and maintained for an additional 3-day safety observation period. The primary outcome was Breathlessness, Cough, and Sputum Scale (BCSS) score evaluated on day 5. Secondary outcomes included the evaluation of cough and dyspnea items in the Visual Analogue Scale (VAS) from days 1-5, remission rate in BCSS and VAS during the treatment course, and the length of hospitalization and in-hospital mortality. Results: Of 272 patients assessed for eligibility, 240 were enrolled in the study (n =120 per group). The mean difference in BCSS evaluated on day 5 was a median 1 point [95%CI (1.00, 2.00)], significantly lower in the treatment group compared with the control group (p < 0.001). Similar results were observed in VAS on day 5, with statistics of a median 2 points [95%CI (1.40, 2.50)] in the cough item and a median 1 point [95%CI (0.50, 2.00)] in the dyspnea item, significantly lower in the treatment group compared with the control group (both p < 0.001). The treatment group had a favorable outcome in BCSS and VAS remission rate assessments compared with the control group, with 99.50% vs. 89.17% in BCSS (p = 0.01), 98.33% vs. 75% in the cough item of VAS (p < 0.001), and 88.33% vs. 62.50% in the dyspnea item of VAS (p < 0.001), respectively. No notable adverse effects were observed during the study. No differences were observed in the length of hospitalization between groups (with a median of 7 days for both groups, p = 0.871). Conclusion: Juhongtanke oral solution may be considered to alleviate the clinical symptoms of CAP.

GABPB1-AS1 acts as a tumor suppressor and inhibits non-small cell lung cancer progression by targeting miRNA-566/F-box protein 47.

It has been certified that GABPB1-AS1 is aberrantly expressed and plays as a vital role in some kinds of cancers. However, its expression pattern and functions in non-small cell lung cancer (NSCLC) are still largely unknown. This study aims to assess GABPB1-AS1 expression and biological roles in NSCLC. The expression of GABPB1-AS1 was detected in NSCLC specimens and adjacent normal specimens. CCK8 and Transwell assays were performed to evaluate the effects of GABPB1-AS1 on NSCLC cell proliferation, migration and invasion. Bioinformatics tools and luciferase reporter assays were applied to predict and verify GABPB1-AS1's direct targets. The results revealed that GABPB1-AS1 is sharply reduced in NSCLC specimens and cell lines. CCK8 assays indicated that overexpression of GABPB1-AS1 dramatically reduced NSCLC cell growth, and Transwell assays proved that NSCLC cell migration and invasion were distinctly inhibited by GABPB1-AS1. Exploration of the mechanism uncovered that miRNA-566 (miR-566)/F-box protein 47 (FBXO47) is directly targeted by GABPB1-AS1 in NSCLC. The study demonstrated that GABPB1-AS1 inhibited NSCLC cell proliferation, migration and invasion by targeting miR-566/FBXO47.

A flexible electromagnetic wave-electricity harvester.

Developing an ultimate electromagnetic (EM)-absorbing material that can not only dissipate EM energy but also convert the generated heat into electricity is highly desired but remains a significant challenge. Here, we report a hybrid Sn@C composite with a biological cell-like splitting ability to address this challenge. The composite consisting of Sn nanoparticles embedded within porous carbon would split under a cycled annealing treatment, leading to more dispersed nanoparticles with an ultrasmall size. Benefiting from an electron-transmitting but a phonon-blocking structure created by the splitting behavior, an EM wave-electricity device constructed by the optimum Sn@C composite could achieve an efficiency of EM to heat at widely used frequency region and a maximum thermoelectric figure of merit of 0.62 at 473 K, as well as a constant output voltage and power under the condition of microwave radiation. This work provides a promising solution for solving EM interference with self-powered EM devices.

A novel prognostic model predicts overall survival in patients with nasopharyngeal carcinoma based on clinical features and blood biomarkers.

This study aims to develop and validate a novel prognostic model to estimate overall survival (OS) in nasopharyngeal carcinoma (NPC) patients based on clinical features and blood biomarkers. We assessed the model's incremental value to the TNM staging system, clinical treatment, and Epstein-Barr virus (EBV) DNA copy number for individual OS estimation. We retrospectively analyzed 519 consecutive patients with NPC. A prognostic model was generated using the Lasso regression model in the training cohort. Then we compared the predictive accuracy of the novel prognostic model with TNM staging, clinical treatment, and EBV DNA copy number using concordance index (C-index), time-dependent ROC (tdROC), and decision curve analysis (DCA). Subsequently, we built a nomogram for OS incorporating the prognostic model, TNM staging, and clinical treatment. Finally, we stratified patients into high-risk and low-risk groups according to the model risk score, and we analyzed the survival time of these two groups using Kaplan-Meier survival plots. All results were validated in the independent validation cohort. Using the Lasso regression, we established a prognostic model consisting of 13 variables with respect to patient prognosis. The C-index, tdROC, and DCA showed that the prognostic model had good predictive accuracy and discriminatory power in the training cohort than did TNM staging, clinical treatment, and EBV DNA copy number. Nomogram consisting of the prognostic model, TNM staging, clinical treatment, and EBV DNA copy number showed some superior net benefit. Based on the model risk score, we split the patients into two subgroups: low-risk (risk score ≤ -1.423) and high-risk (risk score > -1.423). There were significant differences in OS between the two subgroups of patients. Similar results were observed in the validation cohort. The proposed novel prognostic model based on clinical features and serological markers may represent a promising tool for estimating OS in NPC patients.

Biomass-Derived Carbon Heterostructures Enable Environmentally Adaptive Wideband Electromagnetic Wave Absorbers.

Although advances in wireless technologies such as miniature and wearable electronics have improved the quality of our lives, the ubiquitous use of electronics comes at the expense of increased exposure to electromagnetic (EM) radiation. Up to date, extensive efforts have been made to develop high-performance EM absorbers based on synthetic materials. However, the design of an EM absorber with both exceptional EM dissipation ability and good environmental adaptability remains a substantial challenge. Here, we report the design of a class of carbon heterostructures via hierarchical assembly of graphitized lignocellulose derived from bamboo. Specifically, the assemblies of nanofibers and nanosheets behave as a nanometer-sized antenna, which results in an enhancement of the conductive loss. In addition, we show that the composition of cellulose and lignin in the precursor significantly influences the shape of the assembly and the formation of covalent bonds, which affect the dielectric response-ability and the surface hydrophobicity (the apparent contact angle of water can reach 135°). Finally, we demonstrate that the obtained carbon heterostructure maintains its wideband EM absorption with an effective absorption frequency ranging from 12.5 to 16.7 GHz under conditions that simulate the real-world environment, including exposure to rainwater with slightly acidic/alkaline pH values. Overall, the advances reported in this work provide new design principles for the synthesis of high-performance EM absorbers that can find practical applications in real-world environments.

Low Innate Immunity and Lagged Adaptive Immune Response in the Re-Tested Viral RNA Positivity of a COVID-19 Patient.

Recent studies have highlighted observations regarding re-tested positivity (RP) of SARS-CoV-2 RNA in discharged COVID-19 patients, however, the immune mechanisms underlying SARS-CoV-2 RNA RP in immunocompetent patients remain elusive. Herein, we describe the case of an immunocompetent COVID-19 patient with moderate symptoms who was twice re-tested as positive for SARS-CoV-2 RNA, and the period between first and third viral RNA positivity was 95 days, longer than previously reported (18-25 days). The chest computed tomography findings, plasma anti-SARS-CoV-2 antibody, neutralizing antibodies (NAbs) titer, and whole blood transcriptic characteristics in the viral RNA RP patient and other COVID-19 patients were analyzed. During the SARS-CoV-2 RNA RP period, new lung lesions were observed. The COVID-19 patient with viral RNA RP had delayed seroconversion of anti-spike/receptor-binding domain (RBD) IgA antibody and NAbs and were accompanied with disappearance of the lung lesions. Further experimental data validated that NAbs titer was significantly associated with anti-RBD IgA and IgG, and anti-spike IgG. The RP patient had lower interferon-, T cells- and B cell-related genes expression than non-RP patients with mild-to-moderate symptoms, and displayed lower cytokines and chemokines gene expression than severe patients. Interestingly, the RP patient had low expression of antigen presentation-related genes and low B cell counts which might have contributed to the delayed anti-RBD specific antibody and low CD8+ cell response. Collectively, delayed antigen presentation-related gene expression was found related to delayed adaptive immune response and contributed to the SARS-CoV-2 RNA RP in this described immunocompetent patient.

Investigation and optimization of Fe/ZnFe2O4 as a Wide-band electromagnetic absorber.

In this research, a facile in-situ growth method was applied to load ZnFe2O4 nanoparticles on carbonyl iron (Fe) flakes. These loaded ZnFe2O4 exhibited cone shape with an average size of ∼200 nm. The results revealed that the frequency region with reflection loss <-10 dB (fE) was up to 6.2 GHz (d = 1.5 mm), suggesting excellent wideband electromagnetic absorption (EM) properties. The electromagnetic absorption mechanism was discussed in depth which attributed to the synergetic effect of Fe and ZnFe2O4. The loaded ZnFe2O4 played a key role on suppressing inverse electromagnetic radiation, eddy effect, simultaneous maintaining moderate magnetic loss ability. Besides, the formed interface of ZnFe2O4/Fe could induce interface polarization relaxation effect at external electromagnetic field, which greatly boosted the effective dielectric loss ability (ε''E). Meanwhile, the interface polarization intensity was controllable by tuning the weight ratio of Fe.

A Voltage-Boosting Strategy Enabling a Low-Frequency, Flexible Electromagnetic Wave Absorption Device.

Nowadays, low-frequency electromagnetic interference (<2.0 GHz) remains a key core issue that plagues the effective attenuation performance of conventional absorption devices prepared via the component-morphology method (Strategy I). According to theoretical calculations, one fundamental solution is to develop a material that possesses a high ε' but lower ε″. Thus, it is attempted to control the dielectric values via applying an external electrical field, which inducts changes in the macrostructure toward a performance improvement (Strategy II). A sandwich-structured flexible electronic absorption device is designed using a carbon film electrode to conduct an external current. Simultaneously, an absorption layer that is highly responsive to an external voltage is selected via Strategy I. Relying on the synergistic effects from Strategies I and II, this device demonstrates an absorption value of more than 85% at 1.5-2.0 GHz with an applied voltage of 16 V while reducing the thickness to ≈5 mm. In addition, the device also shows a good absorption property at 25-150 °C. The method of utilizing an external voltage to break the intrinsic dielectric feature by modifying a traditional electronic absorption device is demonstrated for the first time and has great significance in solving the low-frequency electromagnetic interference issue.

Interface Polarization Strategy to Solve Electromagnetic Wave Interference Issue.

Design of an interface to arouse interface polarization is an efficient route to attenuate high-frequency electromagnetic waves. The attenuation intensity is highly related to the contact area. To achieve stronger interface polarization, growing metal oxide granular film on graphene with a larger surface area seems to be an efficient strategy due to the high charge carrier concentration of graphene. This study is devoted to fabricating the filmlike composite by a facile thermal decomposition method and investigating the relationship among contact area, polarization intensity, and the type of metal oxide. Because of the high-frequency polarization effect, the composites presented excellent electromagnetic wave attenuation ability. It is shown that the optimal effective frequency bandwidth of graphene/metal oxide was close to 7.0 GHz at a thin coating layer of 2.0 mm. The corresponding reflection loss value was nearly -22.1 dB. Considering the attenuation mechanism, interface polarization may play a key role in the microwave-absorbing ability.

Facile Synthesis and Hierarchical Assembly of Flowerlike NiO Structures with Enhanced Dielectric and Microwave Absorption Properties.

In this work, two novel flowerlike NiO hierarchical structures, rose-flower (S1) and silk-flower (S2), were synthesized by using a facial hydrothermal method, coupled with subsequent postannealing process. Structures, morphologies, and magnetic and electromagnetic properties of two NiO structures have been systematically investigated. SEM and TEM results suggested that S1 had a hierarchical rose-flower architecture with diameters in the range of 4-7 µm, whereas S2 exhibited a porous silk-flower architecture with diameters of 0.7-1.0 µm. Electromagnetic performances indicated that the NiO hierarchical structures played a crucial role in determining their dielectric behavior and impedance matching characteristic, which further influenced the microwave attenuation property of absorbers based on them. Due to its hierarchical and porous architectures, S2 had higher microwave absorption performances than S1. The maximum RL value for sample S2 can reach -65.1 dB at 13.9 GHz, while an efficient bandwidth of 3 GHz was obtained. In addition, the mechanism of the improved microwave absorption were discussed in detail. It is expected that our NiO hierarchical structures synthesized in this work could be used as a reference to design novel microwave absorption materials.