Hollow Porous Structure Research Articles

Combination of ZIF-67 derived hollow porous Co9S8 nanocages and MWCNTs for electrochemical hydrogen storage applications

By using zeolitic imidazolate framework of ZIF-67 as the precursor, the hollow porous Co9S8 (H–Co9S8) nanocages are synthesized via the sulfidation reaction and thermal treatment processes. The ordinary solid Co9S8 (S–Co9S8) particles are prepared by hydrothermal method. To improve the conductivity and activity of the Co9S8 materials, H–Co9S8 + MWCNTs and S–Co9S8 + MWCNTs composites are fabricated by ball milling. The electrochemical hydrogen storage properties of H–Co9S8 and H–Co9S8 + MWCNTs electrodes are tested via a three-electrode system for the first time. Ultimately, the H–Co9S8 nanocages with hollow porous structure show higher discharge capacity of 667.1 mAh/g than the S–Co9S8 particles. The electrochemical performance enhanced after doping with MWCNTs. H–Co9S8 + MWCNTs displays the highest discharge capacity of 683.5 mAh/g. Additionally, the preferable high-rate dischargeability, corrosion resistance, and improved kinetic properties are also achieved for H–Co9S8 + MWCNTs. H–Co9S8 with a unique hollow structure and large specific surface area can offer sufficient electrochemical active sites to anchor hydrogen, meanwhile, MWCNTs with excellent electrical conductivity can further provide fast channels for charge transfer and improve the electrocatalytic activity of Co9S8 electrode during the charging/discharging processes.

Constructing N-doped carbon beads-encapsulated CoMn2O4 microboxes with pyramidal walls for enhanced Li storage

Nanostructures of electrode materials have received intense attention due to their special properties including abundant active sites and short ion diffusion path in the field of energy storage and conversion. In this work, nitrogen-doped carbon beads-encapsulated hierarchical CoMn2O4 microboxes with pyramidal walls are constructed based on Kirkendall effect and self-assembly beginning from Co–Mn Prussian blue analog (PBA) microcubes. And the detailed morphological evolution process is investigated. The unique hollow porous structure of CoMn2O4 bimetallic oxide and the polymer pyrolytic carbon with rich nitrogen heteroatoms endow the composite with a large specific surface area and good conductivity, and make it exhibit excellent lithium storage performance. The morphology evolution analysis can provide support for designing unique nanostructures of electrode materials.

Constructing hollow porous Pd/H-TiO2 photocatalyst for highly selective photocatalytic oxidation of methane to methanol with O2

The partial oxidation of methane to methanol with O2 is an attractive catalytic reaction, but the catalysts still face great challenges in terms of activity and selective oxidation, especially how to avoid overoxidation. Herein, Pd/H-TiO2 with a unique hollow porous nanocage structure was prepared for selective photooxidation of methane into methanol by O2 under mild conditions. The as-obtained Pd/H-TiO2 exhibited a high methanol production rate of 4.5 mmol/g/h with selectivity reaching up to 70 % under optimized conditions, exceeding most reported values. The mechanism study indicated that •OH radicals, produced by photogenerated holes, played an important role in the activation of methane into •CH3 species, and the latter was further oxidized into methanol by •O2- radicals formed by photogenerated electrons. The strong metal-support interaction and unique porous hollow structure also effectively enhanced the catalytic activity. These new insights provide us guidance for the design of high-performance photocatalysts for selective photocatalytic oxidation of methane.

Ultrafine Ru nanoparticles in shape control hollow octahedron MOF derived cobalt oxide@carbon as high-efficiency catalysts for hydrolysis of ammonia borane

BackgroundEvolving cost-effective and high-efficiency catalysts for efficient ammonia borane (AB) hydrolysis is highly desired but leftovers are a great challenge. Catalysis with high efficiency may be achieved by rationally modifying the intention and electronic state. MethodsThe development of carbonized zeolite imidazole framework (ZIF-67) based Ru nanoparticles (NPs) dispersed Ru@Co3O4/NC-350 NPs catalyst composition was prepared for the carrier catalysts. The ZIF-67 was introduced with different calcination temperatures for the carbonized porous materials. Only the calcination temperature at 350 °C with Ru@Co3O4/NC-350 NPs shows the good ability in its catalytic activity. The addition of 3.0 wt.% Ru NPs into the hollow ZIF-67 porous metal-organic framework (MOF) yielded highly stable with good morphology and porous. Significant findingsRu NPs dispersed on carbonized Co3O4/NC have a hollow porous structure with a convoluted nano restricted inner region between Co3O4 and NC, allowing for a large number of accessible active sites and easy mass transfer and controlling the carbonized temperature can change the composition of Co3O4/NC heterostructures. These hollow porous carbon materials show much higher turnover frequency during a very short time and also high stability after ten cycles for the AB hydrolysis. This carbonized sample of Ru@Co3O4/NC-350 NPs exhibited increased catalyst stability and materials reusability. There is particularly great potential for industrial application of this catalytic system in fuel cells, because of its simple preparation method, the use of relatively cheap metals, and its highly active catalysis.

Template-free self-assembly of three-dimensional porous graphitic carbon nitride nanovesicles with size-dependent photocatalytic activity for hydrogen evolution

The vesicle structure of g-C3N4 with various unique properties for photocatalysis, but its current synthesis method with complex and environmentally unfriendly still needs to be further optimized. Herein, a facile template-free self-assembly method was reported to synthesize three-dimensional (3D) porous g-C3N4 nanovesicles (PCNNVs) for achieving efficient and durable photocatalytic H2 evolution. In addition, the photocatalytic H2 activities of as-prepared PCNNVs photocatalysts are size-dependent, the large-size PCNNVs-L exhibits the best H2 production rate of 10.3 mmol h−1 g−1, which is 7 times as high as than that of bulk g-C3N4. The improvement of PCNNVs photocatalysts is mainly from the following points: (i) the porous hollow cavity structure enables it to absorb more photons and form multiple reflections; (ii) the high specific surface area that increases the active site and accelerates the photocatalytic reaction; (iii) ultra-thin shell structure provides a short diffusion channel for electrons’ migration from the volume to the surface; (iv) the hydrophilicity of PCNNVs evidently accelerates electron transportation, resulting in the fast seperation of photo-induced charge carriers. Given the potential and superiority of PCNNVs themselves, this research provides design ideas and reference for developing diverse morphologies of g-C3N4-based photocatalysts.

Hollow porous SiC spheres prepared by in-situ reaction with efficient microwave absorption

The microscopic morphology and structure design of absorbent materials are critical concerns in microwave absorption. The adjustment of morphology and structure can significantly affect absorbing properties. In this work, the hollow porous SiC spheres (HPSS) are prepared by simple self-assembly technology and in-situ reaction (ISR). The results show that the particle size and the shell thickness of HPSS can be controlled by changing the temperature. The special hollow porous structure improves the impedance matching of HPSS and exerts a substantial impact on absorption performance. HPSS being different temperature displays different electromagnetic wave (EMW) absorption properties. Especially, when the temperature reaches 1550 °C, the minimum reflection loss (RLmin) value reaches −51.35 dB and the maximum effective absorption bandwidth (EABmax) is 5.43 GHz at 2.08 mm. The excellent property is ascribed to the synergetic effect of good impedance matching and strong dielectric loss brought by HPSS. This work not only provides an approach to designing special hollow porous structures by ISR but also offers instruction for the effect of the morphology and structure on microwave absorption.

A highly-efficient electrocatalyst for room temperature sodium-sulfur batteries: assembled nitrogen-doped hollow porous carbon spheres decorated with ultrafine α-MoC1-x nanoparticles

While room-temperature sodium-sulfur (RT Na-S) battery is considered one of the most promising technologies for next-generation energy storage, its commoditization is constrained by the shuttling and sluggish redox kinetics of the sulfur electrode. Herein, a honeycomb-like sulfur electrocatalyst with ultrafine α-MoC1-x nanoparticles uniformly distributed on nitrogen-doped hollow porous carbon spheres (MoC@NHC) is designed and synthesized. Prepared through a template-assisted strategy followed by a self-assembly and pyrolysis process, the interconnected hollow porous structure of MoC@NHC provides not only a microenvironment for confinement of sodium polysulfides (NaPSs) but also sufficient free space for accommodation of volume change during electrochemical cycling. Moreover, the polar α-MoC1-x nanoparticles coupled with N-doped carbon provides strong affinity to NaPSs and promote catalytic conversion of NaPSs, as confirmed by experimental results and theoretical calculations. Owing to the physical and chemical dual confinement effect and the fast conversion kinetics of NaPSs, the S/MoC@NHC-15 cathode demonstrates good rate performances (351.8 mAh g−1 at 10 C) and outstanding cyclability (retaining capacities of 418.4 and 312.6 mAh g−1 after 1000 cycles at 1 and 5 C, respectively). This study introduces a simple and effective method for fabrication of S/MoC@NHC cathode materials for high-performance RT Na-S batteries.

Electrospinning preparation of hollow porous Sn0.84Sm0.08Sb0.08O2 micro/nano fibers and their multispectral compatible stealth properties

SnO2 material has good stability, electrical conductivity and high visible light transmittance, showing great potential in the field of stealth materials. However, it is an important research topic that how to improve its multispectral compatible stealth performance, meet the requirements of combat weapons against all-round attack, and conform to the development trend of “thin, light-weight, wide-band and high-performance” stealth materials. Therefore, Sn0.84Sm0.08Sb0.08O2 micro/nano fibers material was prepared by coaxial electrospinning method combined with heat treatment process in this work. The material has a three-dimensional hollow porous fiber structure, and has a larger specific surface area and better compatible stealth performance than solid core fibers. The hollow porous Sn0.84Sm0.08Sb0.08O2 micro/nano fibers material shows good absorbing ability in X-band. When the matching thickness is 2.6 mm, its effective absorbing bandwidth is 3.51 GHz, and when the matching thickness is 2.8 mm, its lowest reflection loss(RL) is −22.51 dB at 10.3 GHz. Secondly, it has a lower infrared emissivity in the infrared detector working bands of 3–5 μm and 8–14 μm, which are 0.558 and 0.672, respectively. Finally, it has reflectivity at the laser operating wavelengths of 1.06 μm and 1.55 μm, which are 7.9% and 2.1%, respectively. The material achieves the organic unity of high absorption in the radar band, low emissivity in the infrared band and low reflectivity at the laser wavelength. At the same time, this work explores the regulation mechanism of the hollow porous structure on electromagnetic wave absorption, infrared emissivity and laser reflectivity, which provides a certain reference for the development of single-type, light-weight, high-performance multispectral compatible stealth materials.

High sensitivity and broad linearity range pressure sensor based on hierarchical in-situ filling porous structure

Flexible piezoresistive pressure sensor with high sensitivity over a broad linearity range have been attracting tremendous attention for its applications in health monitoring, artificial intelligence, and human-machine interfaces. Herein, we report a hierarchical in-situ filling porous piezoresistive sensor (HPPS) by direct ink writing (DIW) printing and curing of carbon nanofibers (CNFs)/polydimethylsiloxane (PDMS) emulsion. Hierarchical geometry significantly increases the contact area, distributes stress to multilayered lattice and internal porous structure, resulting in a broad sensing range. Moreover, unlike conventional hollow porous structure, the CNFs networks in-situ filling porous structure generates more contact sites and conductive pathways during compression, thereby achieving high sensitivity and linearity over entire sensing range. Therefore, the optimized HPPS achieves high sensitivity (4.7 kPa−1) and linearity (coefficient of determination, R2 = 0.998) over a broad range (0.03–1000 kPa), together with remarkable response time and repeatability. Furthermore, the applications in diverse pressure scenarios and healthcare monitoring are demonstrated.

Ultrasensitive photoelectrochemical sensing platform based on heterostructural CuO/NCDs@Au nanocomposites with the efficient photo-induced carrier separation

Heterogeneous composite is considered a valuable material to boost the photo-electrochemical (PEC) properties. Herein, the porous hollow and thin-shell CuO particles were prepared by calcining a Cu-BTC precursor. N-doped carbon dots (NCDs) as both reductor and stabilizer can reduce the Au+ to gain regularly nanoflower NCDs@Au, which further to create type-Ⅱ heterogeneous interface of CuO/NCDs@Au. PEC monitoring results showed that the CuO/NCDs@Au nanocomposite displayed markedly improved photocurrent response than the monocomponent CuO or CuO/NCDs. This outstanding photoelectric property was ascribed to the multiple reflection/scattering effects from the porous hollow structure of CuO particles which led to more photo-induced e−/h+ pairs. The obtained heterostructured CuO/NCDs@Au could magnify synergistically the photocurrent output signal. Ab (antibodies) was accurately immobilized on the CuO/NCDs@Au modified ITO electrode via a facility amidation reaction. Fabricated Ab/CuO/NCDs@Au/ITO PEC sensing platform for AFP (alpha-fetoprotein) detection manifested an enhanced sensitivity (3.32 × 10-4 ng mL−1) with wide linear range (0.001 ∼ 300 ng mL−1), which was superior compared to the electrochemical results. This works developed an excellent heterojunction nanocomposite of CuO/NCDs@Au, which provided well-synthesized strategies for structuring high-performance photocatalysts based on MOFs derivant.

Elaboration of Ni2P@C Composites with Hollow Porous Structure for Enhanced Overall Water Splitting

AbstractThe electrocatalytic water splitting is greatly affected by overpotential, stability, and accessibility of active sites. Designing appropriate active components and tailoring their microstructure are crucial to improve electrocatalytic performance. Herein, using metal organic framework (MOF) as template, novel Ni2P@C composites are prepared as bifunctional catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The best Ni2P@C‐350 sample has a small onset overpotential (η) of 57 mV, and up to 148 and 285 mV to afford 10 and 250 mA cm–2 for HER. It only needs η = 326 mV at 10 mA cm−2 for OER, better than usual RuO2 electrode. Moreover, Ni2P@C‐350||Ni2P@C‐350 cell can work for overall water splitting more efficiently than common Pt/C||RuO2 cell, running stably within 30 h without obvious degradation. The excellent performance is attributed to its porous structure with easily accessible active sites, short ions transfer path, and superior structural stability, which enable a significant improvement on molecule level, e.g., the turnover frequency (TOF) of Ni2P@C‐350 at η = 250 mV is up to 0.84 s−1, while that of pristine Ni2P is only 0.55 s−1. These results highlight the effect of structure engineering, inspiring for electrode design of HER and OER.

Interconnected Hollow Porous Polyacrylonitrile-Based Electrolyte Membrane for a Quasi-Solid-State Flexible Zinc-Air Battery with Ultralong Lifetime.

Quasi-solid-state flexible zinc-air batteries (FZABs) have received enormous attention due to their low cost and high safety. However, the constraints in lifetime resulting from the lack of stable quasi-solid-state electrolyte membranes and efficient bifunctional electrocatalysts toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) hinder the large-scale manufacture and commercialization of FZABs to power electric devices. Herein, a polyacrylonitrile (PAN)-based membrane (HPPANP) fabricated via facile coaxial electrospinning, water dissolution, lyophilization, and KOH preimmersion method was utilized as the quasi-solid-state electrolyte membrane. The interconnected hollow porous structure based on PAN nanofibers endows HPPANP with outstanding electrolyte-uptake/retention capabilities for high ionic conductivity and nanolevel wetted electrolyte/anode interface for uniform Zn dissolution/deposition, thus prolonging the lifespan of the FZABs. In addition, the in situ alkaline hydrolysis of KOH solution supplies HPPANP with abundant oxygen-containing groups, which also improves its ionic conductivity. Additionally, we synthesized a Co/N-doped hollow carbon sphere (CoN-CS) electrocatalyst that exhibits superior ORR and OER electrocatalytic activities with a low potential difference (ΔE) of 0.73 V. Such favorable ORR and OER performances can be mainly attributed to the hierarchical hollow micro/nanostructures with abundant active sites, long-term stability, and favorable electron/ion diffusion pathway. As a result, the assembled FZAB equipped with the CoN-CS catalyst and HPPANP displays high power density (123.8 mW cm-2) and preferable long-term cycling performance (more than 50 h at 3 mA cm-2).

Synthesis and electrochemical properties of ZnMn2O4 with hollow porous panpipe-like structure as anode material for Li-ion battery

In this work, ZnMn2O4 anode material with excellent lithium storage performance is prepared by combining the carbon gel–combustion method and the hard template strategy (a polypropylene membrane with high porosity). The as–obtained ZnMn2O4 sample has a hollow panpipe–like structure with rich pore characteristics. The phase composition, micro–nano structure, crystallinity, pore size distribution, specific surface area, element distribution and valence state of the samples are systematically tested and analyzed by XRD, ICP–AES, FESEM, TEM, HRTEM, N2 adsorption/desorption measurement and XPS. When assembled into a half–cell with metallic lithium as the counter electrode, the ZnMn2O4 electrode material exhibits higher reversible capacity (under low and high current densities), excellent cycle stability and rate capability with better dynamic properties compared with the ZnMn2O4 sample obtained without using the organic template agent. Porous structure characteristics, small particle size, high specific surface area, high crystallinity and special micro–nano structure help to effectively improve the kinetic properties and structural stability of the electrode material during charge/discharge processes for achieving high energy and power densities.

Rational design of a hollow porous structure for enhancing diffusion kinetics of K ions in edge-nitrogen doped carbon nanorods

Rational design of a hollow porous structure for enhancing diffusion kinetics of K ions in edge-nitrogen doped carbon nanorods

Texturing In-Situ: N/F Dual-Doped hollow porous carbon nanospheres for advanced Li-S batteries

Heteroatom-doped hollow carbon nanostructures are one of the most promising sulfur hosts for high-performance lithium-sulfur (Li-S) batteries. However, finding a facile and controllable synthesis and enhancing their immobilization effect on polysulfides have been challenging. Herein, we propose a one-step in-situ reaction approach to synthesize N/F dual-doped hollow micro/mesoporous carbon nanospheres (NFHCs) as multifunctional sulfur host, which integrates the physical confinement of hollow porous structure and chemical adsorption/catalytic ability of N/F active sites to realize strong anchoring and accelerated conversion of polysulfides. This sulfur cathode based on NFHCs host with a high sulfur content of 80 wt% enables a superior high-rate capacity of 689 mAh g−1 at 3C, accompanied by outstanding cycle life over 500 cycles at 2C with a capacity decay of only 0.05% per cycle and nearly 100% Coulombic efficiency. This work opens up new horizons to design nanostructured functional hollow carbons for advanced Li-S batteries.

Post-modified porous hollow nanospheres incorporating multiple strategies for comprehensive phosphoproteomics analysis of serum of Alzheimer's disease

Alzheimer's disease (AD), as a neurodegenerative disease, has become a major disease threatening the physical and mental health of the elderly. In order to find potential cost-effective and valuable AD biomarkers from human serum, we developed and designed a post-modified functional nanomaterial denoted as H–CeO2@PEI-Ti with a porous hollow structure modified with polyethyleneimine (PEI) and Ti4+. This post-modified porous hollow nanomaterial integrated multiple enrichment strategies, including immobilized metal ion affinity chromatography (IMAC) and metal oxide affinity chromatography (MOAC) with electrostatic interaction synergy and hydrogen bond assistance was applied to the phosphoproteomics for the first time. The experimental results demonstrated good performance in the enrichment of standard phosphoprotein tryptic digests, such as extremely low detection limit (0.02 fmol), excellent selectivity (1:5000 M ratio of β-casein and BSA), given that the large specific surface area created by the special porous hollow structure. In serum analyses, 49 phosphopeptides corresponding to 31 phosphoproteins were identified in the serum of the normal controls, and 49 phosphopeptides corresponding to 32 phosphoproteins in AD patients. More importantly, some functional items based on Gene Ontology (GO) analysis after enrichment for human serum supported the molecular biological processes that may be related to the pathogenesis of AD, including copper ion binding, heparin binding and retinoid metabolism.

Insertion of carbon skeleton in Ni/MoO2 heterojunction with porous hollow sphere for efficient alkaline electrochemical hydrogen production

The catalyst morphology has a strong impact on the activity of electrocatalytic hydrogen production. Considering the effect, we design and fabricate hollow spherical Ni/MoO2 heterojunction. In addition, an amorphous carbon skeleton is inserted into the hollow sphere, which makes the structure more stable and porous. Compared with other morphological Ni/MoO2, the porous hollow spherical Ni/MoO2 (H-Ni/MoO2) with an internal carbon skeleton shows better hydrogen evolution reaction (HER) activity with a small overpotential of 58 mV to reach 10 mA cm−2 and a tafel value of 44.8 mV dec-1 in alkaline media. The developed HER performance of H-Ni/MoO2 can be attributed to the larger active surface area of porous hollow spherical structure and the faster electron transfer and better stability of carbon skeleton. Undoubtedly, the urea plays a crucial role to construct the hollow spherical morphology and being decomposed to form holes and amorphous carbon in the synthesized steps. The soft-template strategy using urea as the addition for forming the porous hollow structure with carbon skeleton can be extended to explore superior non-noble metal for hydrogen production.

Preparation of NIR-Responsive Gold Nanocages as Efficient Carrier for Controlling Release of EGCG in Anticancer Application.

Hepatocellular carcinoma (HCC) is a type of cancer that has a restricted therapy option. Epigallocatechin gallate (EGCG) is one of the main biologically active ingredients in tea. A large number of studies have shown that EGCG has preventive and therapeutic effects on various tumors. In addition, the development of near-infrared (NIR)-responsive nano-platforms has been attracting cancer treatment. In this work, we designed and synthesized a strategy of gold nanocages (AuNCs) as an efficient carrier for controlling release of EGCG for anti-tumor to achieve the synergistic functions of NIR-response and inhibited tumor cell proliferation. The diameter of AuNCs is about 50 nm and has a hollow porous (8 nm) structure. Thermal imaging-graphic studies proved that the AuNCs-EGCG obtained have photothermal response to laser irradiation under near-infrared light and still maintain light stability after multiple cycles of laser irradiation. The resulted AuNCs-EGCG reduced the proliferation rate of HepG2 cells to 50% at 48 h. Western blot analysis showed that NIR-responsive AuNCs-EGCG can promote the expression of HepG2 cell apoptosis-related proteins HSP70, Cytochrome C, Caspase-9, Caspase-3, and Bax, while the expression of Bcl-2 is inhibited. Cell confocal microscopy analysis proved that AuNCs-EGCG irradiated by NIR significantly upregulates Caspase-3 by nearly 2-fold and downregulates Bcl-2 by nearly 0.33-fold, which is beneficial to promote HepG2 cell apoptosis. This study provides useful information for the NIR-responsive AuNCs-EGCG as a new type of nanomedicine for HCC.

Engineering hierarchically ZnS/NiS/NiS2 hollow porous urchin-like composite towards exceptional lithium storage

Complex hollow structure nanostructure is regarded as the desired approach to alleviating the volume change of lithium-ion batteries (LIBs). In this work, ZnS/NiS/NiS2 composite with a distinctive hierarchical hollow porous urchin-like structure was prepared through pyrolysis of bimetal-organic frameworks obtained by one-step solvothermal and firstly used as anodes for LIBs. Varying the metal molar ratios allows the control of the surface area and pore size distribution of ZnS/NiS/NiS2. The obtained composite with a hollow porous urchin-like structure exhibits high porosity, large specific surface area, and strong synergetic interaction between ZnS and NiS/NiS2 can greatly buffer the volume expansion to keep the mechanical stability, ensure sufficient contact region between electrolyte and electrodes and shorten the Li+ transfer distance, meanwhile, the carbon derived from organic ligand of bimetal-organic frameworks also constructs the conductive matrix to accelerate electrons transfer. Based on the above outstanding properties, the obtained material delivers excellent rate capacity, superior reversible capacity, and long-cycle stability, especially disclosing a capacity of 615 mAh·g−1 after 300 cycles at 2 A·g−1. This work proposes a feasible strategy to obtain a unique hollow porous urchin-like structure through pyrolysis of bimetal organic frameworks, it can be extended to fabricate other mixed metal sulfides nanostructures with excellent electrochemical performances.

Confined transformation of trifunctional Co2(OH)2CO3 nanosheet assemblies into hollow porous Co@N-doped carbon spheres for efficient microwave absorption

Carbonaceous-magnetic composites are the most appealing candidates for electromagnetic wave absorption, and creating hollow interiors and nanopores in the composites is commonly recognized as an essential strategy to reinforce their overall performances. Herein, we propose a spatial confinement strategy mediated by Co2(OH)2CO3 nanosheet assemblies for achieving highly dispersed Co nanoparticles into hollow porous N-doped carbon shells (HP-Co@NCS). Systematic multi-technique characterizations indicate that the Co2(OH)2CO3 nanosheet assemblies simultaneously play a trifunctional role during the synthesis, including Co source, template of the hollow interior cavities, and micro-/mesopore porogen. The chemical composition can be modulated by simply varying the ratio of Co2(OH)2CO3 and carbon source (dopamine). The optimized HP-Co@NCS absorber exhibits a well-defined hollow structure and unprecedented high porosity (specific surface area of 742 m2 g−1) even with a high metallic Co content of 35.8 wt%. These profitable structural characteristics can facilitate incident EM waves penetrating the absorber's interior and promoting multiple reflections and scattering. Therefore, the HP-Co@NCS absorber exhibits efficient microwave absorption ability with a minimum reflection loss of −39.0 dB at a thin thickness of 2.5 mm and an effective absorption bandwidth up to 5.5 GHz (12.5–18.0 GHz) at a thin thickness of 2.0 mm. This work provides a new methodology to design advanced carbonaceous-magnetic composite materials with hollow porous structures for microwave absorption.