Urchin-like Structure Research Articles

Synthesis and characterization of chitosan/cellulose blend reinforced with copper oxide nanoparticles as moisture barrier film

Bio-based plastics emerged as eco-friendly and resource-efficient substitutes for petroleum-based counterparts. Despite the continuous efforts to develop these alternatives, their inferior performance, most notably mechanical and moisture barrier aspects, limits their application. Material hybridization, like polymer blending and nanocomposite technology, are among the methods employed to improve the properties of bioplastics. This present work focuses on synthesizing bioplastic films with 30/70, 50/50, and 70/30 chitosan to cellulose (CH/CE) percent weight ratios. FTIR analysis of the blend films revealed interaction between NH2 and OH, confirming the compatibility between chitosan and cellulose. Analysis of variance showed increasing cellulose content significantly (p < 0.05) enhanced the resistance to swelling. The 30/70-CH/CE film exhibited the least swelling, which is 65.5% lower than the pure chitosan film. Moreover, copper oxide nanoparticles (CuO NPs) were prepared as reinforcement due to its hydrophobicity. Structural and morphological analyses of hydrothermally synthesized CuO nanoparticles confirmed monoclinic and urchin-like structure. Varying amounts of CuO NPs, i.e., 1%, 3%, and 5% w/v were added to the 30/70-CH/CE films to further enhance the moisture barrier properties. The best barrier performance was attained at 5% w/v, indicated by the smallest % swelling (93.25%) and largest contact angle measurement (89.32°). This could be related to the morphological change from fibrous to smoother film surface with increasing amount of CuO NPs. Results suggest the potential of the chitosan/cellulose polymer blend and the copper oxide nanoparticle-reinforced films for moisture barrier applications.

Effective and selective electrocatalytic nitrate reduction to ammonia on urchin-like and defect-enriched titanium oxide microparticles

This work reported a facile approach to surface oxygen vacancy (OV)-enriched urchin-like TiO2 microparticles (U-TiO2), which were highly effective and durable in catalyzing selective nitrate reduction to ammonia (NO3RR). Specifically, the U-TiO2 delivered a mass activity of 1.15 min−1 mg−1catalyst, a low yield of toxic NO2−-N intermediate (≤0.4 mg/L) and an exceptional high NH3-N selectivity of 98.1% in treating 22.5 mg/L of NO3−-N under a potential of -0.60 V vs. RHE, outperforming most of the reported oxide-based catalysts. When comparing the performance of U-TiO2 with that of the solid amorphous TiO2 counterpart (A-TiO2) that had close particle size but more OV on surfaces, we identified that the OV was the reactive sites, but rather than its content, the NO3RR kinetics were primarily limited by the electron and mass transfer at U-TiO2/water interfaces. Accordingly, the superior performance of U-TiO2 to A-TiO2 could be ascribed to the hierarchical urchin-like structure in U-TiO2. The in-situ DEMS test revealed that the NO3RR on U-TiO2 followed a pathway of *NO3− → *NO2−→ *NO → *N → *NH → *NH2 → *NH3. We also demonstrated that the U-TiO2 could keep its robust performance under a wide NO3−-N concentration range and in the presence of some co-existing ions (such as Ca2+, Cl−, Mg2+). However, the presence of humic acid and CO32− in water slowed down the NO3RR on U-TiO2. This work provides a more fundamental insight into the OV-driven NO3RR process on TiO2, which should benefit for the development of efficient TiO2-based catalysts.

Three-dimensional urchin-like N/S co-doped Mn-based metal-organic frameworks for efficiently enabling oxygen reduction reaction

The exploration of economical and effective non-noble metal catalysts is essential for oxygen reduction reaction (ORR) in energy devices. Recently, heteroatom-doped metal-organic frameworks (MOFs) have shown great potential in ORR due to their high efficiencies and low costs. Herein, three-dimensional (3D) urchin-like N/S co-doped Mn-based MOFs (U–N/S–Mn-MOFs) as an effective ORR catalyst have been successfully prepared by a facile one-step solvothermal methodology. The unique 3D urchin-like structure with a spherical interior and dendritic exterior may provide more catalytic sites and transport channels for ORR. Simultaneously, the doped N and S combined with Mn can promote oxygen adsorption and reduce the reaction energy barrier. These characteristics endow U–N/S–Mn-MOFs with high ORR performance. The present work provides a new opportunity for multiple heteroatom-doped MOFs to achieve high electrocatalytic performance.

Diesel soot oxidation over potassium-promoted urchin-structured NiO-NiCo2O4 catalyst

Catalytic oxidation is an effective strategy to eliminate soot emitted from diesel engines. However, the insufficient contact sites and low intrinsic activity of catalysts severely limit the development of the technique. Herein, we designed and prepared a potassium-promoted NiO-NiCo2O4 composite endowed with an urchin-like structure (K/NiO-NiCo2O4 US), which displayed high catalytic activity for soot oxidation with temperatures of soot conversion at 10% (T10) and 50% (T50) as low as 307 °C and 347 °C, respectively. The enhanced performance was unveiled based on a series of characterization results. On one hand, the urchin-like structure increased the contact efficiency between the soot and the catalyst. On the other hand, the loading of potassium generated more Co3+ species and active oxygen species, improving the oxidation ability.

Ammonia sensing properties of PPy nanostructures (urchins/flowers) towards low-cost and flexible gas sensors at room temperature

High-performance room-temperature gas sensors have tremendous potential in real-world applications like air quality control, food safety, and health monitoring. In this work, we report an eco-friendly and one-step route for the chemical synthesis of hierarchical polypyrrole (PPy) nanotubes assembled urchins and flower-like nanostructures via a template-assisted method and examine their morphology-dependent gas sensing characteristics. The ammonia sensor was mounted on low-cost and highly flexible polyvinylidene fluoride (PVDF) membrane substrate for the fabrication of flexible sensor. The polypyrrole urchins and flower-like nanostructures exhibited high surface area of 194.9 m2/g and 101.05 m2/g along with highly porous structure confirmed by BET and SEM characterization. The nanotubes assembled urchin-like structure of PPy exhibited great response, repeatability, and long-term durability to NH3 gas in the range of 1–200 ppm owing to their high porosity, excellent flexibility, and large surface area. In addition, the PPy urchins based sensor exhibited low response time (23 s) and very high response of 34.7% towards 100 ppm concentration of ammonia gas at room temperature. From the flexibility point of view, proposed flexible sensor showed high mechanical robustness under extreme bending conditions, i.e. 900 bending angle and 400 bending cycles by showing no considerable change in response even after these extreme bending conditions. The proposed flexible gas sensor remarkable performance to detect ammonia at room temperature indicates its tremendous potential for wearable electronics applications.

Oxygen deficient sea urchin-like Cu-WO3 with high capacity and long life for anode of lithium-ion battery

Cation-doping and oxygen vacancy (Vo) engineering are powerful strategies to address the low conductivity, sluggish ion kinetics and short cycling life facing in metal oxide. Herein, a series of Cu-doped WO3 with Vo was prepared via a facile hydrothermal method. The results show the ratio of Cu/W plays an important role in morphology regulation and the corresponding electrochemical performance. When the molar ratio of Cu/W is 0.3, the sea urchin-like structured WCu0.3 could be achieved. In this architecture, nanowire is propitious to furnish plentiful transmission channels, paving the way to high rate capability. The sea urchin-like structure with large surface area and rich mesoporous can accommodate the strain during repeat lithiation/delithiation processes, giving rise to high capacity and superior cycling durability. Additionally, the Vo induced by Cu-doping is favorable to the enhancement of conductivity. These combined merits endow WCu0.3 with impressive 1st discharge capacity (1585 mAh g−1 at 0.1 A g−1), good rate capability (621.2 mAh g−1 at 0.1 A g−1 and 520.2 mAh g−1 at 0.5 A g−1) and cycle performance (796.3 mAh g−1 over 300 cycles under 0.5 A g−1). Our work provides a simple approach to optimize metal oxide’s lithium storage performance via Vo regulation by cation-doping.

Characterization of CuO doped CdO nanomaterials synthesized by sol gel spin coating and hydrothermal method

CuO-CdO nanomaterials were synthesized by sol gel spin coating and hydrothermal methods. Undoped CdO and 0.2%, 0.5%, 1%, and 2% CuO doped CdO were produced as thin films and nanopowders. The structural, optical, and electrical properties of the thin films and nanopowders produced were investigated. It was determined by X-ray diffraction (XRD) analysis that thin films and nanopowders were polycrystalline and face-centered cubic structures. From Atomic Force Microscope (AFM) images, it was observed that the structure of the thin films was homogeneous and dense rod-shaped structures, and the nanopowders were urchin-like structures consisting of spherical nanoparticles from the Field Emission Scanning Electron Microscopy (FESEM) images. It was determined that nanopowder and thin films have direct band transition from Ultraviolet–visible spectroscopy (UV–Vis) analysis. From all the results obtained, it was concluded that structural, optical, and electrical properties of thin films and nanopowders vary depending on the doping rate and method differences.

Design and synthesis of nickel-doped cobalt molybdate microrods: An effective electrocatalyst for the determination of antibiotic drug ronidazole

Ronidazole (RDZ) is a veterinary antibiotic drug that has been used in animal husbandry as feed. However, improper disposal and illegal use of pharmaceuticals have severely polluted water resources. Doping/substitution of metal ions is an effective strategy to change the material's crystal phase, morphology, and electrocatalytic activity. In this work, nickel (Ni2+)-doped cobalt molybdate microrods (NCMO MRs) were prepared for the electrochemical detection of RDZ. The catalyst was prepared by reflux method followed by calcination at 500 °C. The prepared catalyst was confirmed by various spectroscopic and microscopic analyses. XRD and Raman spectroscopy demonstrated that the phase transition from β-CoMoO4 to α-CoMoO4 was achieved by Ni2+ doping. The SEM analysis showed that cobalt molybdate (CMO) microrods were self-assembled during Ni2+ doping and formed an urchin-like structure, and the average diameter of the MRs was ±50 nm. The electrocatalytic activity of the catalysts was analyzed using the CV technique. The NCMO MRs/GCE exhibited the higher current response than the pristine CMO. The electron transfer coefficient (α = 0.56) and heterogeneous rate constant (ks = 0.32 s−1) of NCMO MRs/GCE were evaluated by kinetic studies. In addition, the diffusion coefficient of RDZ was determined to be 2.32 × 10−5 cm2/s. Moreover, NCMO MRs/GCE exhibits a low detection limit for RDZ (15 nM) as well as a higher sensitivity (1.57 μA μM−1 cm−2). The fabricated RDZ sensor was successfully applied to analysis of lake and tap water samples. Based on the results, we believe that the as-prepared NCMO MRs/GCE is a viable electrode material for RDZ sensors in environmental monitoring.

An integrated colorimetric and photothermal lateral flow immunoassay based on bimetallic Ag–Au urchin-like hollow structures for the sensitive detection of E. coli O157:H7

Lateral flow immunoassay (LFIA) with gold nanoparticles (AuNPs) as the signal reporter is widely used for the rapid detection of food-borne pathogens. However, it is difficult for LFIA to achieve sensitive detection due to the insufficient colorimetric signal brightness of AuNPs. Herein, we developed a bimetallic Ag–Au urchin-like hollow nanospheres (BUHNPs) based on the simple and rapid synthesis through co-reduction and galvanic replacement reactions. The BUHNPs exhibit superb colorimetric signal brightness, strong photothermal signals and high antibody coupling efficiency. The obtained colorimetric and photothermal LFIA (BUHNPs-CM-LFIA and BUHNPs-PT-LFIA) based on BUHNPs were used for the sensitive detection of a pathogenic bacterium (Escherichia coli O157:H7). The limit of detection values of the colorimetric and photothermal quantitative analysis were 2.48 × 103 and 5.50 × 102 CFU mL−1, which were approximately 4-fold and 18-fold lower than that of AuNPs-LFIA (9.92 × 103 CFU mL−1), respectively. This work suggests that a dual-readout LFIA with BUHNPs as a promising signal reporter can be used to improve the detection performance of LFIA and construct a more accurate and sensitive detection platform.

Urchin-Like Structured MoO2 /Mo3 P/Mo2 C Triple-Interface Heterojunction Encapsulated within Nitrogen-Doped Carbon for Enhanced Hydrogen Evolution Reaction.

The development of highly efficient and cost-effective hydrogen evolution reaction (HER) catalysts is highly desirable to efficiently promote the HER process, especially under alkaline condition. Herein, a polyoxometalates-organic-complex-induced carbonization method is developed to construct MoO2 /Mo3 P/Mo2 C triple-interface heterojunction encapsulated into nitrogen-doped carbon with urchin-like structure using ammonium phosphomolybdate and dopamine. Furthermore, the mass ratio of dopamine and ammonium phosphomolybdate is found critical for the successful formation of such triple-interface heterojunction. Theoretical calculation results demonstrate that such triple-interface heterojunctions possess thermodynamically favorable water dissociation Gibbs free energy (ΔGH2O ) of -1.28eV and hydrogen adsorption Gibbs free energy (ΔGH* ) of -0.41eV due to the synergistic effect of Mo2 C and Mo3 P as water dissociation site and H* adsorption/desorption sites during the HER process in comparison to the corresponding single components. Notably, the optimal heterostructures exhibit the highest HER activity with the low overpotential of 69mV at the current density of 10mA cm-2 and a small Tafel slope of 60.4mV dec-1 as well as good long-term stability for 125h. Such remarkable results have been theoretically and experimentally proven to be due to the synergistic effect between the unique heterostructures and the encapsulated nitrogen-doped carbon.

Enhanced gas-sensing to low-concentration ethanol gas from 3-dimensional (3D) urchin-like ZnO micro/nanospheres

Highly sensitive and long-term stable ethanol gas sensors based on 3D urchin-like ZnO micro/ nanospheres are synthesized. The formation mechanism of the 3D urchin-like ZnO structure is analyzed. The 3D urchin-like ZnO micro/nanospheres sensor displayed a high sensitivity of 15.0, a fast response time of 14 sec, and a recovery time of 7 sec when detecting 200 ppm ethanol gas at the optimal operating temperature of 280 °C. Moreover, the sensor is in the low concentration of ethanol gas for 450 days, in this case, the sensitivity of the sensor is 5.9, when detecting 200 ppm ethanol gas at an operating temperature 280 °C. The prepared 3D urchin-like ZnO micro/nanospheres have higher response strength to low-concentration ethanol gas and still have good stability after long-term storage

Phosphorescent LaCO3OH core-satellite superstructures with highly efficient photocatalysis

Luminescent lanthanum hydroxycarbonates (LaCO3OH) have received considerable attention because of their excellent photocatalytic activities. The luminescent properties of the LaCO3OH are closely related to their morphology and crystallization, but phosphorescent LaCO3OH has not yet been observed. Herein, the LaCO3OH core-satellite superstructures (LaCO3OH-CSSs), which consist of a porous structure as a core and urchin-like structures as the satellites, are prepared using a simple hydrothermal method. The proposed LaCO3OH-CSSs have strong solid-state luminescence and highly effective solution room-temperature phosphorescence with a lifetime of 163.5 ms. Combination with the advantages of both porous structure and slow charge recombination, the LaCO3OH-CSSs show superior photocatalytic activities, which can be used for highly efficient photodegradation of model rhodamine 6G (R6G) dyes. The R6G dyes can be completely degraded within 5 min under low-power white light (21 W) irradiation. The highly efficient photocatalytic activity suggests that phosphorescent LaCO3OH-CSSs can be well used for the treatment of water pollution.

Urchin-like Co3O4 as a heterogenous peroxymonosulfate catalyst for crystal violet degradation: Reaction kinetics and process optimization

Advanced oxidation processes based on the sulfate radicals (SR-AOPs) have been considered as promising methods to eliminate the organic contaminants from wastewater. In this work, the urchin-like Co 3 O 4 was prepared and developed as an efficient heterogenous catalyst to activate peroxymonosulfate (PMS) for the degradation of an active dye, crystal violet (CV). The morphological observations by SEM and TEM confirmed a distinct urchin-like structure of as-prepared Co 3 O 4 sample. XRD pattern indicated that all the characteristic diffraction peaks belonged to Co 3 O 4 with the face-centered-cubic spinel structure. The contrast experiments showed that the CV degradation efficiency in urchin-like Co 3 O 4 /PMS system was much higher than that in pristine PMS or Co 3 O 4 system, suggesting that PMS could be effectively activated by the urchin-like Co 3 O 4 for CV degradation. Kinetic studies revealed that CV degradation reaction in urchin-like Co 3 O 4 /PMS system followed the retarded first-order model. The process optimization of CV degradation was implemented by response surface methodology (RSM), and then the optimum conditions were determined. • Specific urchin-like Co 3 O 4 was designed and employed for PMS activation. • The detailed reaction kinetics study reflects the complexity of the degradation process. • The process of degradation was further optimized via response surface methodology.

Highly crystalline carbon nitride with small-sized sea urchin-like structure for efficient photocatalytic hydrogen production under visible-light irradiation

Molten-salt method has been deemed as a feasible strategy to increase the crystallinity of graphitic carbon nitride (abbreviated as CN), thereby improving its photocatalytic activity. However, highly crystalline CN prepared by molten-salt method using bulk carbon nitride (BCN) as the precursor still suffers from a small specific surface area, which is unfavorable to the separation of photogenerated carriers. Here, we report a facile approach to obtain highly crystalline CN with a large specific surface area using tubular carbon nitride (TCN) as raw material, and the final sample is named as tubular carbon nitride-molten salt (TCN-M). Compared with bulk carbon nitride-molten salt (BCN-M) sample, the obtained TCN-M sample not only retains the advantage of high crystallinity, but also exhibits a smaller-sized sea urchin-like structure owing to the CN precursor pretreatment process. The experiment results demonstrate that TCN-M displays an excellent hydrogen production activity of 4.9 mmol g -1 h -1 under visible-light, and its hydrogen production performance can be further enhanced to 14.7 mmol g -1 h -1 after adding 0.5 M K 2 HPO 4 . Thus, this work may supply valuable ideas to further optimize the photocatalytic activity of highly crystalline CN prepared by molten-salt method from the perspective of CN precursor pretreatment. • A highly crystalline carbon nitride with small-sized sea urchin-like structure was successfully prepared. • Large specific surface area and the presence of cyano groups greatly improve the photocatalytic H 2 production activity. • Optimizing the photocatalytic activity of highly crystalline CN from the perspective of CN precursor pretreatment. • A typical H + -reduction cycle can be constructed by introducing K 2 HPO 4 into the reaction system.

Experimental and Theoretical Exploration of In Situ Grown Fe3S4/Co3S4 Heterostructure as Efficient Catalyst for I3 − Reduction Reaction

Evolving low-cost transition metal sulfides heterostructures using simple yet high-efficiency synthesis methods to be grown directly on fluorine-doped tin oxide glass (FTO) as a counter electrode (CE) is an immense challenge for dye-sensitized solar cells (DSSCs). Herein, Fe3S4/Co3S4 heterostructures with urchin-like structures were uniformly deposited on FTO substrates by a two-step hydrothermal reaction. DSSC constructed with the Fe3S4/Co3S4 CE achieves high power conversion efficiency (8.43%), which is better than the pure Pt CE (7.60%) measured under the same circumstances. The high performance comes down to the fact that Fe3S4/Co3S4 grows directly on the surface of FTO and achieves the uniform film thickness, which is conducive to the full contact of the electrolyte and accelerates the charge transfer. Moreover, density functional theory (DFT) indicates that the charge density changes at the interface of Fe3S4/Co3S4 enhance the interaction between Fe 3d orbitals and I 5p orbitals, thereby the synergistic effect between Fe3S4 and Co3S4 achieving outstanding catalytic performance for I ions. This work paves the way for direct growth of heterostructure materials on substrates as electrodes avoiding subsequent complex processing for energy-related fields.

Preparation of porous and hierarchical tantalum oxide particles using hydrolyzing tantalum alkoxide

• Spherical hydrous Ta 2 O 5 particles were prepared using hydrolyzing Ta alkoxide. • Hydrous Ta 2 O 5 particles became porous after being soaked in 2-propanol. • Hydrothermal treatment crystallized porous hydrous Ta 2 O 5 particles. • The Ta 2 O 5 particles had urchin-like shapes with high specific surface areas. Tantalum oxide (Ta 2 O 5 ) particles with defined structures and high specific surface areas are highly desirable for diverse applications. Herein, hydrous Ta 2 O 5 particles with porous structures were prepared by hydrolyzing tantalum alkoxide and partially dissolving the particle surfaces by soaking in alcohol. To obtain crystallized Ta 2 O 5 , these particles were subjected to heat treatment or hydrothermal treatment. Heat treatment produced particles that retained the original porous structure to some extent, while hydrothermal treatment caused dried hydrous Ta 2 O 5 particles to disintegrate. In contrast, hydrothermal crystallization of nondried hydrous Ta 2 O 5 particles produced an urchin-like structure, with Ta 2 O 5 spines grown on the original spherical core. The urchin-like particles had a mesoporous structure with a specific surface area of about 75 m 2 g −1 .

Hollow urchin-like CoSe2 with high surface area as highly efficient electrocatalyst for oxygen evolution

• A novel hollow urchin-like CoSe 2 have been achieved using urchin-like Co(OH) 2 as template. • The annealed CoSe 2 with more active sites and ideal electronic structure can be used as highly efficient electrocatalyst for oxygen evolution. • This material only requires an overpotential value of 285 mV at the 10 mA·cm −2 current density. • This material shows excellent stability. CoSe 2 is considered as a terrific replacement for the noble metal oxides to accelerate the oxygen evolution reaction (OER). Herein, we develop a novel hollow urchin-like CoSe 2 using urchin-like Co(OH) 2 as template. The as-prepared CoSe 2 was treated at 300 °C. It displays low overpotential of 285 mV at the 10 mA·cm −2 current density, which is much lower than that of the treated flake CoSe 2 and untreated hollow urchin-like CoSe 2 . The cyclic voltammetry (CV) curves clearly demonstrated that the lager electrochemical active surface area of the CoSe 2 is attribute to the hollow urchin-like structure and the increase of the active site by heat treatment. Moreover, the heat treatment increases the number of antibonding orbitals of Co-Se, which is close to the ideal filling for OER. Therefore, the synergistic effect of the increased electrochemical active surface area and optimized electronic configuration enhances electrocatalytic activity of the catalyst. These results demonstrate the potential of hollow urchin-like CoSe 2 in the field of energy conversion and storage technologies, and open up a novel avenue to design of high surface area catalysts with excellent performance and durability as alternatives to the noble metal oxides.

Solution-processable multicolor TiO2/polyaniline nanocomposite for integrated bifunctional electrochromic energy storage device

We report a solution-processable nanocomposite film based on TiO2 and polyaniline (PANI) for high-performance electrochromic and energy storage via the combination of electrostatic spray deposition (ESD) and electropolymerization (EPM) techniques. This combined strategy provides an exciting method for high-performance metal oxide/conducting polymer composite with well-controlled morphology and structure. The obtained TiO2/PANI composite film with a sea urchin-like porous structure exhibits a unique electron donor–acceptor (D-A) structure, facilitating the electron transport from PANI to TiO2. As a result, the nanocomposite film presents excellent electrochemical performances in both electrochromic and energy storage aspects, such as large optical modulation up to 76.9 % at 600 nm, short switching time (<3.6 s), and high coloration efficiency (CE) of 78 cm2 C-1. Furthemore, an intelligent energy-storage indicator with energy level monitoring functionality is designed and constructed based on the multicolor composites, in which the energy-storage level can be visually detected in real-time by the different color variations. This work paves a way for developing multicolor nanomaterials in the field of bifunctional electrochromic energy storage.

Pseudocapacitive boosts nanoparticles composed of sea urchin structure Bi2S3-xSex@rGO with high rate and capacity for sodium ion battery anode

The abundant reserve and low cost of sodium over lithium has prompted an enormous development for sodium-ion batteries(SIBs). SIBs are expected to replace lithium ion batteries in the future and be widely applied. Reliable anodes are one of the key issues in the commercial application of SIBs. Herein, an elaborate sea urchin-shaped Se-doped Bi2S3 (Bi2S3-xSex@rGO) electrode is designed by hydrothermal method for SIBs. The Bi2S3-xSex@rGO electrode exhibits an excellent rate capability (694 mAh g −1 at 2 A g−1)and high reversible capacity (701 mAh g −1 after 100 cycles at 0.1 A g −1), which are superior to those of most Bi2S3 for SIBs anode reported previously. Pseudocapacitive contribution is demonstrated as the main reason of prominent electrochemical performance of the Bi2S3-xSex@rGO electrode. The sea urchin-like structure is composed of bismuth sulfide nanoparticles, which promotes the pseudocapacitance behavior of the electrode. The pseudocapacitance promoted by rapid transport of sodium ions could extend to more advanced SIBs anodes.

Autogenous and Tunable CNTs for Enhanced Polarization and Conduction Loss Enabling Sea Urchin-Like Co3ZnC/Co/C Composites with Excellent Microwave Absorption Performance.

ZIF-67-derived magnetic metal/carbon composites are considered prospective candidates for use as microwave absorption (MA) materials owing to their magnetoelectric synergy. However, the structure of ZIF-67-derived MA materials mainly depends on the morphology and composition of pristine metal-organic frameworks (MOFs), and their microstructures lack a rational design. Herein, a multidimensional sea urchin-like carbon nanotubes (CNTs)-grafted carbon polyhedra-encapsulated Co3ZnC/Co nanoparticle composite was prepared by one-step catalytic pyrolysis of ZIF-67/ZnO using a rational structural design. The autogenous and tunable CNTs obtained with the assistance of zinc evaporation not only overcome the limitation of homogeneous dispersion but also endow the Co3ZnC/Co/C composite with outstanding MA properties owing to the conduction loss provided by CNTs, polarization loss caused by multiple components, and electromagnetic wave trap composed of a special sea urchin-like structure. Consequently, the minimum reflection loss of ZZ0.1-600 reaches -60.3 dB at 1.6 mm, the maximum absorption bandwidth of ZZ0.05-600 is 6.24 GHz (covering nearly the entire Ku band) at 1.9 mm, and the structure has a low weight ratio (30 wt %). Compared with Z-600 and pure ZnO, the MA performance of the sea urchin-like Co3ZnC/Co/C composite obtained by rational structural design has been greatly improved; this strategy offers a new approach for optimizing the MA performance of materials according to their structural design.