Structure Of Multi-walled Carbon Nanotubes Research Articles

Fe2O3-decorated multiwall carbon nanotube composites for boosted microwave absorption

Developing microwave absorption (MA) materials with a strong absorption ability over a wide bandwidth through a simple and environmentally friendly approach remains a tremendous challenge. Herein, we propose to use an Fe3+–tannic acid framework to assist the dispersion of multi-walled carbon nanotubes (MWCNTs) and successfully prepare MWCNTs/porous carbon/α-Fe2O3 composites through freeze-drying and subsequent heat treatment. The dielectric properties and MA performance can be regulated by the heat treatment temperature, which leads to tunable crystalline structure, composition, and graphitization degree of MWCNTs. Consequently, the MWCNTs/porous carbon/α-Fe2O3 composite heat-treated at 300 °C exhibits a high reflection loss (RL) of −58.9 dB and an effective absorption bandwidth (5.28 GHz) with a matched thickness of 2.26 mm at a filler proportion of only 5 wt%, and the related frequency bandwidth with RL below −10 dB reaches 14.3 GHz at a thickness of 2–5 mm. In conclusion, the balance between conduction and polarization loss endows the composite with excellent impedance matching and boosting MA performance. This study offers a guideline for fabricating excellent MA materials through a simple, environmentally friendly method.

Structural and morphological studies of g-C3N4-functionalized MWCNTs nanocomposite for sunlight-responsive photocatalytic activity

Photocatalytic degradation of organic contaminants has been proven to be one of the greatest economical and efficient techniques to address environmental pollution problems. Multi-walled carbon nanotubes (MWCNTs)/g-C3N4 (GCN) nanocomposites (NCs) were synthesized by a hydrothermal process aided by ultrasound to produce active photocatalysts. The effective synthesis of GCN, MWCNTs, and MWCNTs/GCN NCs was confirmed by X-ray diffraction (XRD) patterns. The fabrication of GCN nanosheets (NSs), the nanotubular structure of MWCNTs, and a network of neuron-like structures for MWCNTs/GCN NCs were all revealed by structural and morphological characterization. The elemental mapping of NCs containing the suitable quantity of MWCNTs revealed a uniform distribution of the sample's component elements. When the optical properties of the fabricated nanomaterials were examined by employing UV–visible spectroscopy, the results revealed a blue shift (a shift of maximum absorption to the UV region), which suggests that the addition of MWCNTs increased the band-gap energy. The behaviour of e––h+ pair recombination was revealed by measuring the charge carrier movement and trapping efficiency using photoluminescence (PL) spectroscopy. Crystal violet (CV) dye was photocatalytically degraded using prepared NCs in the presence of sunlight, and the synergistic effects of GCN and MWCNTs were examined. With a degradation efficiency of 99.32 %, MWCNTs/GCN NCs demonstrated the best sunlight-irradiated photocatalytic activity for CV degradation. The degradation of CV was discovered to follow pseudo-first-order kinetics. Throughout five consecutive studies, the NCs demonstrated the highest levels of catalytic efficiency and recyclability, with 5 % reduced degrading activities. The trapping tests showed that the primary reactive species involved in the breakdown of CV were the •O2– and •OH radicals.

Enhanced oxygen evolution and power density of Co/Zn@NC@MWCNTs for the application of zinc-air batteries

Rechargeable zinc-air batteries (ZABs) are viewed as a promising solution for electric vehicles due to their potential to provide a clean, cost-effective, and sustainable energy storage system for the next generation. Nevertheless, sluggish kinetics of the oxygen evolution reaction (OER), the oxygen reduction reaction (ORR) at the air electrode, and low power density are significant challenges that hinder the practical application of ZABs. The key to resolving the development of ZABs is developing an affordable, efficient, and stable catalyst with bifunctional catalytic. In this study, we present a series of bifunctional catalysts composed of Co/Zn nanoparticles uniformly embedded in nitrogen-doped carbon (NC) and multi-walled carbon nanotubes (MWCNTs) denoted as Co/Zn@NC@MWCNTs. The incorporation of MWCNTs using a facile and non-toxic method significantly decreased the overpotential of the OER from 570 to 430 mV at 10 mA cm−2 and the peak power density from 226 to 263 mW cm−2. Besides, the electrochemical surface area measurements and electrochemical impedance spectroscopy indicate that the three-dimensional (3D) network structure of MWCNTs facilitates mass transport for ORR and reduces electron transfer resistance during OER, leading to a small potential gap of 0.86 V between OER and ORR, high electron transfer number (3.92–3.98) of the ORR, and lowest Tafel slope (47.8 mV dec−1) of the OER in aqueous ZABs. In addition, in-situ Raman spectroscopy revealed a notable decrease in the ID/IG ratio for the optimally configured Co/Zn@NC@MWCNTs (75:25), indicating a reduction in defect density and improved structural ordering during the electrochemical process, which directly contributes to enhanced ORR activity. Hence, this study provides an excellent strategy for constructing a bifunctional catalyst material with a 3D MWCNTs conductive network for the development of advanced ZAB systems for sustainable energy applications.

Application of 3D structure of carbon nanotube-interwoven metal–organic frameworks in solid-phase microextraction of trace polychlorinated biphenyls from tea beverages

A three-dimensional (3D) structure of multiwalled carbon nanotubes (MWCNTs) interwoven metal–organic frameworks (MOFs) was synthesized. The MWCNTs was utilized to bridge the neighboring MOF nanocrystals. The hybrid material MOFs/MWCNTs was used for SPME coating to extract six PCBS in tea beverages samples by gas chromatography coupled to tandem mass spectrometry. MOFs/MWCNTs coating materials were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and N2 adsorption–desorption analysis. The response surface method was utilized to systematically optimize the main extraction factors. Under the optimized conditions, the developed method demonstrated wide linear ranges (0.01–1000 ng·L−1), low limits of detection (0.003–0.009 ng·L−1) and high enrichment factors (701–2361) for extracting and determining six PCBS. The six PCBS concentration in environmental tea beverages samples was detected with this method. These results display that MOFs/MWCNTs hybrid materials are potential sorbents in the SPME of PCBS in environmental tea beverages samples.

Exploration of the photothermal role of curcumin-loaded targeted carbon nanotubes as a potential therapy for melanoma cancer

In this research, the hydrophilic structure of multi-walled carbon nanotubes (MWCNTs) was modified by synthesizing polycitric acid (PCA) and attaching folic acid (FA) to create MWCNT–PCA–FA. This modified nanocomplex was utilized as a carrier for the lipophilic compound curcumin (Cur). Characterization techniques including TGA, TEM, and UV–visible spectrophotometry were used to analyze the nanocomplex. The mechanism of cancer cell death induced by MWCNT–PCA–FA was studied extensively using the MTT assay, colony formation analysis, cell cycle assessment via flow cytometry, and apoptosis studies. Furthermore, we assessed the antitumor efficacy of these targeted nanocomplexes following exposure to laser radiation. The results showed that the nanocomposites and free Cur had significant toxicity on melanoma cancer cells (B16F10 cells) while having minimal impact on normal cells (NHDF cells). This selectivity for cancerous cells demonstrates the potential of these compounds as therapeutic agents. Furthermore, MWCNT–PCA–FA/Cur showed superior cytotoxicity compared to free Cur alone. Colony formation studies confirmed these results. The researchers found that MWCNT–FA–PCA/Cur effectively induced programmed cell death. In photothermal analysis, MWCNT–PCA–FA/Cur combined with laser treatment achieved the highest mortality rate. These promising results suggest that this multifunctional therapeutic nanoplatform holds the potential for combination cancer therapies that utilize various established therapeutic methods.

The impact of synergistic action of methacrylic acid/zinc oxide/carbon nanotubes on metal Friction and wear

The continuous operation of essential refining equipment, internal mixers, leads to wear on their end faces, resulting in an increased gap between the mixer chamber and the end face. This, in turn, causes material leakage, reducing mixing efficiency and adversely impacting rubber performance. Therefore, investigating metal wear on the mixer's end face during the mixing process is essential. Scholars have introduced dynamic covalent bonds into rubber molecular chains, bestowing self-repairing capabilities upon the materials. This innovation has significant implications for extending rubber lifespan and lowering production costs. It involves adding methacrylic acid (MAA) and excess zinc oxide (ZnO) to construct an ionic crosslinking network, limiting covalent crosslinking of rubber molecules and enabling in-situ polymerization of MAA/ZnO, resulting in self-repairing properties. However, it is crucial to consider corrosive wear induced by MAA's strong acidity on metals. This study combines MAA, ZnO, and multi-walled carbon nanotubes (MWCNTs) through mechanical mixing to create a composite material called zinc methacrylate (ZDMA)/MWCNTs/rubber. The research investigates the in-situ synthesis mechanism of MAA and ZnO and the synergistic mechanism of ZDMA and MWCNTs. The study analyzes the impact of MWCNTs additive amount on the frictional wear of the internal mixer's metal end face. During the mixing process, ZDMA is grafted and polymerized onto rubber's macromolecular chains, forming ionic pairs with strong electrostatic interactions, creating a primarily reversible supramolecular network dominated by ion crosslinking. This ion crosslinking network, along with the three-dimensional mesh structure of MWCNTs, establishes a stable spatial structure within the rubber matrix. The study reveals that increasing the MWCNTs content to 3 phr reduces the aggregation of SiO2 particles and ZDMA granules within the rubber matrix, resulting in reduced friction coefficients, roughness, and wear rates of the metal. However, exceeding 3 phr of MAA content leads to excessive MWCNT aggregation within the rubber matrix, increasing wear rates, roughness, and friction coefficients due to hindrance of rubber macromolecular chain crosslinking and reduced SiO2 particle dispersion within the rubber matrix. These findings provide valuable insights into the dynamics of frictional wear in internal mixers.

The Effect of He:O Plasma Treatment on the Structure of Multi-Walled Carbon Nanotubes

The Effect of He:O Plasma Treatment on the Structure of Multi-Walled Carbon Nanotubes

Thermal prediction of rotatory multiwall carbon nanotubes subject to convective boundary conditions and slip effects: Implicit finite difference simulations

This article presents the modeling and simulations 3D magneto-hydrodynamic rotating nanofluid flow through a stretched surface. Water is employed as the base liquid, and multiwall carbon nanotubes (MWCNTs) are used as nanosized materials. The unique structure of MWCNTs makes them stand out among the crowd. The principal concern is to enhance the thermal transport efficiency, chemical durability, and important optical and electronics properties. The classical Navier Stoke’s problem based upon the law of conservation of mass, momentum and energy with the Xue model’s implementation is transformed into an ordinary differential equation by applying similarity approach. Velocity slip and convective boundary conditions are also considered under the Lorentz force. The final form of nondimensional ODEs are, then, solved numerically using finite difference method with the assistance of MATLAB's powerful software. The impression of pertinent convergence flow constraints on fluid velocity, temperature, heat transfer rate, and friction factor are exposed through tables and graphs. A numerical comparison is used to evaluate the code efficiency, and the results show excellent agreement. The effect of the Biot number appears to be raising the temperature. Conversely, increasing the rotation and slip parameter parametric values results in a declining trend in the velocity profile.

Few-layer V2C/MWCNT with high ionic accessibility for lithium-ion storage.

A V2C MXene has a high theoretical capacity and low diffusion barrier, showing tremendous potential in lithium-ion batteries. However, most reports on V2C focus on a multilayered structure that is stacked, which diminishes the ionic accessibility and results in unsatisfactory cycling stability. Therefore, we synthesized a few-layer V2C (f-V2C) material and added multi-walled carbon nanotubes (MWCNTs). The formed f-V2C/MWCNT provides abundant pores, which enhance ionic accessibility, so that Li+ can easily enter the layer space. The introduction of MWCNTs can further separate the f-V2C, expand the specific surface area, reduce the charge transfer resistance, and heighten the structural stability. The experiments reveal that f-V2C/MWCNT has a high specific capacity of 531 mA h g-1 at 0.1 A g-1 after 100 cycles. Even at a high current density of 5.0 A g-1, the specific capacity can still reach 166 mA h g-1. Moreover, the f-V2C/MWCNT structure shows good cycling stability with a capacity retention rate of 95% after 1000 cycles at 5.0 A g-1. The above findings indicate that f-V2C/MWCNT has great application potential in the field of Li+ storage.

Wrapping ZIF-67 with vine-like carbon nanotubes to enhance the capture of polysulfide and consolidation of active site

The shuttle effect of polysulfide and slow reaction kinetics has hindered the commercialization of lithium–sulfur batteries. Here, metal organic framework (MOF)-derived nitrogen-doped carbon was used as templates, and the continuous interspersed filamentary network structure of multi-walled carbon nanotubes (MWCNT) was used as a modifier to synthesize Co-NC@MWCNT. The exposure of Co-MOF with a high density of catalytic sites in the pores effectively improves the sulfur stability capacity of the composite and inhibits the shuttle effect. The outermost layer of coated MWCNTs and the intermediate layer of N-doped porous carbon effectively protected the Co2+ active site of the dodecahedral configuration from easy deactivation and agglomeration. The prepared Co-NC@MWCNT composite had an initial discharge capacity of 1240 mA h g−1 (0.1C), it maintained a low decay rate of 0.054 % after 1000 cycles (0.5C). The graphite-like layer gap and multilayer tube structure of the networked MWCNT can effectively mitigate volume expansion during charging and discharging and provide Li+ transport channels to improve electrical conductivity. Moreover, the energy storage devices developed as part of this work have excellent electrochemical properties and have a noteworthy industrial potential.

Preparation of voltammetric sensors for taurine detection from Cu(II)-loaded carbon materials

ABSTRACT. In this study, for the detection of taurine in philological fluids, modified electrodes were prepared from glassy carbon electrodes with MWCNT (multi-wall carbon nanotube) + Cu(NO3)2 + carbon-based material. A carbon-based material was obtained by carbonization of Pinus sylvestris branch needles (CPS). Cu(NO3)2 and MWCNT structure (Cu(NO3)2/MWCNT) were added to the carbon-based material and the obtained mixture was used in the modification of the glassy carbon electrode surface. The surface morphology and structure of the prepared electrodes were characterized by electron microscopy scanning (SEM) and atomic force microscopy (AFM). Taurine detection with a modified electrode was made by cyclic voltammetry (CV) in 0.1 M KCl (vs. Ag/AgCl). The calibration curve of the modified electrode for taurine in the 10-150 µM range showed a linear response, and R2 value was 0.976. Limit of detection (LOD) and limit of quantification (LOQ) of the modified electrode were found 19 µM and 9.75 µM, respectively. The application of the electrode as a chemical sensor was carried out with commercially available energy drink samples. Satisfactory results have been obtained from the samples. The sensor can be used for routine taurine analysis. This electrode can quickly determine the amount of taurine in real samples with 90% accuracy in two minutes.
 KEY WORDS: Taurine detection, Modified electrode, MWCNT, Sensor, Cyclic voltammetry
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1565-1576. DOI: https://dx.doi.org/10.4314/bcse.v37i6.20

The Effect of Multi-Wall Carbon Nanotubes Addition on the Shielding Properties Against Gamma Radiation

In this work, the effect of Multi-Wall Carbon Nanotubes (MWCNTs) addition on the materials shielding properties against Gamma radiation with an energy of 662 keV from a 137Cs source is investigated. The linear attenuation coefficient of MWCNTs-based materials (gelatin-water mixture) with MWCNTs concentrations of 0%, 5%, and 10% is measured. To isolate the contribution of the MWCNTs unique structure to the shielding capabilities, samples with the same concentrations of activated carbon were fabricated and their linear attenuation coefficients were obtained. Also, the linear and the mass attenuation coefficients are obtained theoretically for the same concentrations using the XCOM program and compared with measured values. It is found that the addition of MWCNTs by 5% or 10% has increased the linear attenuation coefficient by around 5% when compared to the same concentrations of activated carbon. This increase in the shielding apabilities against gamma radiation can be related to the interaction of gamma radiation with the extraordinary geometry and structure of MWCNTs.

The excellent microwave absorption properties of the composite structure of 3D flower-like layered double hydroxide derivatives and multi-walled carbon nanotubes

The control of electromagnetic pollution and military affairs both heavily rely on the absorption and attenuation of electromagnetic waves. NiO/Co3O4 obtained by pyrolysis of NiCo-layered double hydroxides retained the structural framework of the precursor and introduced a porous structure in the pyrolysis process, which effectively enhanced the multiple reflections and scattering of electromagnetic waves. Furtherly, multi-walled carbon nanotubes were embedded into bimetallic oxides to create a conductive network and introduce polarization groups, resulting in a reflection loss of −56.90 dB and an absorption bandwidth of 6.19 GHz. Compared to traditional metal oxides, the NiO/Co3O4-MWCNT composite greatly improved the wave absorption effect. Such a new structure provided a new idea for the application of LDH in the field of wave absorption.

PPy@MWCNT Nanocomposite for Supercapacitor Applications

Polypyrrole (PPy) is a potential electrode material for supercapacitors due to its properties suchas high conductivity and chemical stability. However, additional additives can be used to further improvethe capacity values and energy storage performance of PPy. Multi-walled carbon nanotubes (MWCNT) arenanomaterials with properties such as high surface area, excellent conductivity and mechanical strength,and can improve supercapacitor performance when integrated into the PPy matrix. In this study, synthesis,characterization and performance analysis were performed to evaluate the potential of PPy and MWCNTdoped PPy in supercapacitor applications. PPy and MWCNT doped PPy were characterized using analyticaltechniques such as XRD (X-ray diffraction) analysis and SEM (scanning electron microscopy) imaging.XRD analysis was used to determine the crystal structures and crystal sizes of the material and showed thatthe crystal structures of PPy and MWCNT doped PPy were preserved. SEM imaging was used to examinethe surface morphology of the material and it was observed that it has a homogeneous surface structure.Supercapacitor performance was evaluated using electrochemical characterization methods. PPy andMWCNT doped PPy samples exhibited high capacitance values and fast charge-discharge properties. Theintegration of the MWCNT additive into the PPy matrix allowed the electrode to maintain its chemicalstability while increasing the surface area. These results show that PPy and MWCNT doped PPy have thepotential to provide more efficient energy storage in supercapacitors.

Influence of MWCNTs additives on the thermal conductivity of HA–MWCNTs composite

Possible changes in the temperature dependence of the coefficient of thermal conductivity of the hydroxyapatite (HA) composite with multi-walled carbon nanotubes (MWCNTs) with small amounts of MWCNTs additives (0.5 wt%) were analyzed in comparison with the dependence of HA matrix without additives. It was found that MWCNTs can contribute to the increase of the thermal conductivity coefficient. The magnitude of the effect of increasing thermal conductivity varies from relatively small values (about 1%) to a significant increase up to ∼ 20 times that depending on the interaction at the HA–MWCNTs interface and the degree of homogeneity of the MWCNTs distribution in the HA matrix. It was found that long-term high-temperature annealing can lead to changes in the anisotropy, structure, and properties of MWCNTs due to oxidation effects, which can influence the resulting composite properties.

Unveiling thereinforcement potentiality of MWCNTs architecture towards the improvement of microstructural vis-a-vis mechanical and thermo-mechanical properties of pressureless sintered MgAl2O4 spinel ceramic composite

The study presented in this work focuses on the preparation of composites made of multi-walled carbon nanotubes (MWCNTs) and magnesium aluminate spinel through a pressureless sintering technique. The effects of sintering temperature and MWCNTs content on the densification behavior and mechanical properties of the composite were investigated in detail. The results revealed that the composite exhibited improved densification behavior, enhanced mechanical performance and decent control at the microstructural refinement with increasing MWCNTs content up to 0.75 wt%. The superior mechanical properties obtained in case of sintered composite were attributed to the synergetic toughening mechanisms involving the fiber pull out, cracks bridging and cracks deflection effects of reinforcing phases, observed as a resultant effect of strong interfaces with the matrix phase. The crystalline structural arrangement obtained from the XRD and Raman spectral analysis of the composites structure also satisfies the attainment of the promising reinforcement potential of the nanotubular structure. Most importantly, the study also exemplified the subsidiary interference of a surface decorative coating on the MWCNTs structure with the MgAl-binary oxide network. The strategic grafting of the oxide protective shell and the consequent development of a robust interfacial bridging network between the matrix and reinforcement phase regulated the energy dissipation characteristic for fiber debonding. This, in turn, restricted the crack growth phenomenon during mechanical loading, and thereby ultimately contributing to the enhanced fracture toughness, reduced thermal expansion co-efficient and augmented thermo-mechanical performance of the evolved spinel-based composite structure

Study on spalling and cracking behavior of MWCNTs concrete exposed to high temperatures

AbstractThis study aims to investigate the effects of multiwalled carbon nanotubes (MWCNTs) on the spalling and cracking behavior of concrete exposed to high temperatures, and also consider the mechanism of different cooling methods (including natural air cooling, spray cooling, and quench cooling) on its performance after high temperature. Meanwhile, the change rules of mechanical properties and pore structure of MWCNTs reinforced concrete during high temperature and cooling were explored by x‐ray computed tomography. The results demonstrated that spalling and cracking behavior of the concrete specimens exposed to high temperatures was effectively controlled by adding MWCNTs. Consequently, the thermal resistance and residual mechanical properties of concrete exposed to high temperatures were significantly improved. Moreover, the mesoscopic and microscopic observation showed that the MWCNTs have a favorable impact on reducing the porosity of the concrete specimens below 600°C. However, when the temperature exceeded 600°C, MWCNTs reached the burning point and lost the bridging effect. No trace of MWCNTs was observed in the concrete specimen, but the cumulative mitigation decreased the possibility of cracking and spalling of concrete at 800°C. Additionally, considering the influence of cooling methods, it is found that the spalling and cracking of the concrete specimens after high temperature caused by quench cooling were the most serious, while that of caused by spray cooling were the least.

Adsorption of Phenanthrene on Multi-Walled Carbon Nanotubes in the Presence of Nonionic Surfactants.

The bioavailability and mobility of phenanthrene (Phe) adsorbed by multi-walled carbon nanotubes (MWCNTs) may be substantially influenced by nonionic surfactants used both in the synthesis and dispersion of MWCNTs. The adsorption mechanisms of Phe adsorbed onto MWCNTs under the different nonionic surfactants Tween 80 (TW-80) and Triton X-100 (TX-100) in the aqueous phase were investigated in terms of changes in the MWCNTs' compositions and structures. The results showed that TW-80 and TX-100 were easily adsorbed onto MWCNTs. Phe adsorption data onto MWCNTs were better suited to the Langmuir equation than the Freundlich equation. Both TW-80 and TX-100 reduced the adsorption capacity of Phe onto MWCNTs. When TW-80 and TX-100 were added in the adsorption system, the saturated adsorption mass of Phe decreased from 35.97 mg/g to 27.10 and 29.79 mg/g, respectively, which can be attributed to the following three reasons. Firstly, the hydrophobic interactions between MWCNTs and Phe became weakened in the presence of nonionic surfactants. Secondly, the nonionic surfactants covered the adsorption sites of MWCNTs, which caused Phe adsorption to be reduced. Finally, nonionic surfactants can also promote the desorption of Phe from MWCNTs.

Low-loading oxidized multi-walled carbon nanotube grafted waterborne polyurethane composites with ultrahigh mechanical properties improvement

The uniform dispersion of oxidized multi-wall carbon nanotubes (OCNT) in waterborne polyurethane (WPU) matrix was achieved by in-situ polymerization, endowing the OCNT/WPU composite film with enhanced tensile strength, thermal stability, and excellent elongation at break. The structure of multi-wall carbon nanotubes (CNT) and OCNT was characterized by TEM, XRD, XPS, and the structure and morphology of composites were characterized by particle size analysis, SEM and FT-IR. Compared with pure WPU and OCNT/WPU composite, the breaking strength and the thermal degradation temperatures of 20 % weight loss of the OCNT/WPU composite were increased by 175 % and 353 °C, respectively. The oxygen-containing functional groups effectively improved the surface active of OCNT, making it easier for OCNT to react with polyurethane prepolymers. After addition of only 1 % OCNT, the tensile strength approaches 77 MPa while the elongation at break remains at 277 %. In addition to having outstanding chemical and mechanical properties, OCNT have a better dispersibility rate than multiwalled carbon nanotubes, which means that they will have a broader application range. • By in situ polymerization, oxidized carbon nanotubes are grafted into polyurethane systems. • Oxidized carbon nanotubes offer better performance than pristine carbon nanotubes. • Adding 1 % oxidized carbon nanotubes to waterborne polyurethane improved mechanical properties by 175 %.

Customizing defect location in MWCNTs/Fe3O4 composites by direct fluorination for enhancing microwave absorption performance

Constructing magnetic-dielectric composites is an effective approach to prepare high-performance multi-walled carbon nanotubes (MWCNTs)-based microwave absorbers. The current composite design strategies mainly focus on the regulation of magnetic materials, while the effect of MWCNTs structure on the microwave absorption (MA) performance is still unclear. Herein, F-MWCNTs with different fluorinated depths, namely surface fluorination (S-F-MWCNTs) and deep fluorination (D-F-MWCNTs) were prepared by molecular-fluorination and atomic-fluorination, respectively. The fluorine atoms on F-MWCNTs were defluorinated in the next loading process, achieving customization of defect location in MWCNTs/Fe3O4 composites. In relation to the fluorination depth of F-MWCNTs, the defects of S-F-MWCNTs/Fe3O4 were mainly distributed on the outer tube of MWCNTs, while they were on both inner and outer tubes of MWCNTs for D-F-MWCNTs/Fe3O4. Under the electromagnetic field, the inner tube defects of D-F-MWCNTs/Fe3O4 were excited to produce enhanced polarization loss and conductive loss. As a result, compared with S-F-MWCNTs/Fe3O4 with only outer tube defects, D-F-MWCNTs/Fe3O4 with both inner and outer tube defects exhibited better MA performance. Further regulating the fluorine content of D-F-MWCNTs, we can adjust the optimal absorption band shifting from high frequency to low frequency. Our work illustrates the importance of inner tube modification of MWCNTs to prepare high-performance MWCNTs-based microwave absorbers.