Bamboo-like N-doped Carbon Nanotubes Research Articles

Dual-MOFs-Derived Fe and Mn Species Anchored on Bamboo-like Carbon Nanotubes for Efficient Oxygen Reduction as Electrocatalysts

The development of efficient non-precious metal electrocatalysts for oxygen reduction reaction (ORR) to replace Pt-based methods is crucial for the applications of fuel cells and metal–air batteries. In this study, a bimetallic M-N-C catalyst with highly dispersed dual-atom Fe/Mn-Nx sites immobilized on N-doped bamboo-like carbon nanotubes is prepared by the ball-milling and calcination of dual-MOFs as precursors. The rich N-doping and abundant M–Nx species contribute to the excellent intrinsic ORR activity of the catalyst, and the unique bamboo-like nanotubes morphology is beneficial for facilitating electron transfer and mass transport while simultaneously enabling the exposure of active sites. As expected, the optimized Z-Fe1Mn1-NC catalyst exhibits efficient ORR activity with a half-wave potential (E1/2) of 0.80 V in acid and 0.82 V in alkaline, and a higher electrochemical stability with the current density maintained at 91% (in 0.1 M KOH) and 86% (0.1 M HClO4) of its initial current density after 15 h of a chronoamperometric test at a high potential of 0.7 V. When further applied to Zn–air batteries, the catalyst also delivers a high open-circuit voltage, large power density, and outstanding rate performance. This work provides a novel means of designing dual metal M–Nx site-based M-N-C catalysts for ORR sustainable energy applications.

Ni3Fe@N-doped carbon nanotubes 3D network induced by nanoconfined symmetry breaking for high-performance microwave absorption, corrosion protection, and pollutant purification

It remains challenging to develop multifunctional electromagnetic wave (EMW) absorbers with anti-corrosion and pollutant purification capabilities suitable for extremely harsh ocean environments. This study exploits symmetry breaking to construct a three-dimensional (3D) network of bamboo-like N-doped carbon nanotubes (NCNT) encapsulated with magnetic Ni3Fe nanocatalysts via facile coordination and catalytic chemical vapor deposition process. The resulting Ni3Fe@NCNT composite demonstrates outstanding EMW absorption performance, anti-corrosion behavior, and adsorption purification function. Its excellent EMW absorption performance, including a minimum reflection loss of −57.3 dB and a maximum effective absorption bandwidth of 6.0 GHz, is achieved by magnetic-dielectric match, inert space platform, and porosity architecture. The Ni3Fe@NCNT composite also shows corrosion resistance and self-cleaning function simultaneously because of the physical shield provided by the intrinsically impermeable, inert NCNT shells and their considerable chemically active site and high porosity. For the first time, the EMW absorber is endowed with cooperative multi-functionalities. Our findings may pave the way to manufacture versatile EMW materials for applications in complicated environments.

Ru Catalysts Supported on Bamboo-like N-Doped Carbon Nanotubes: Activity and Stability in Oxidizing and Reducing Environment

The catalysts with platinum-group metals on nanostructured carbons have been a very active field of research, but the studies were mainly limited to Pt and Pd. Here, Ru catalysts based on nitrogen-doped carbon nanotubes (N-CNTs) have been prepared and thoroughly characterized; Ru loading was kept constant (3 wt.%), while the degree of N-doping was varied (from 0 to 4.8 at.%) to evaluate its influence on the state of supported metal. Using the N-CNTs afforded ultrafine Ru particles (<2 nm) and allowed a portion of Ru to be stabilized in an atomic state. The presence of Ru single atoms in Ru/N-CNTs expectedly increased catalytic activity and selectivity in the formic acid decomposition (FAD) but had no effect in catalytic wet air oxidation (CWAO) of phenol, thus arguing against a key role of single-atom catalysis in the latter case. A remarkable difference between these two reactions was also found in regard to catalyst stability. In the course of FAD, no changes in the support or supported species or reaction rate were observed even at a high temperature (150 °C). In CWAO, although 100% conversions were still achievable in repeated runs, the oxidizing environment caused partial destruction of N-CNTs and progressive deactivation of the Ru surface by carbonaceous deposits. These findings add important new knowledge about the properties and applicability of Ru@C nanosystems.

Co3C-stabilized-CoFe heterostructure wrapped by bamboo-like N-doped carbon nanotubes for highly-efficient oxygen electrocatalysis

Bimetallic alloys have been showing unexpectedly high activity for oxygen reduction reaction (ORR) in alkaline electrolytes. However, many fundamental questions regarding the ORR stability and poor oxygen evolution reaction (OER) performance of bimetallic alloys remain unresolved. Here, we prepare a cobalt carbide-stabilized CoFe alloy wrapped by hollow bamboo-like nitrogen-doped carbon nanotubes (CoFe-Co3C@NCNTs) using bimetallic Prussian-blue-analogue and dicyandiamide as precursors. Interestingly, the spherical CoFe-Co3C heterojunctions are always encapsulated at one end of the tube. The as-marked CoFe-Co3C@NCNTs-20 catalyst exhibits an ultra-high ORR activity (half-wave potential of 0.934 V) and a relatively good OER activity (overpotential of 0.320 V), which are superior to Pt/C and RuO2, respectively. CoFe-Co3C@NCNTs-20 also shows excellent ORR/OER stabilities and potential difference between ORR and OER (0.616 V). Excellent activity and stability benefit from the synergies between CoFe-Co3C and NCNTs, while the hollow structure/conductive skeleton enhances the mass/charge transfers, respectively. The NCNTs coating greatly enhances the stability of the CoFe-Co3C heterojunctions to avoid the corrosion of active sites in alkaline media. Moreover, rechargeable zinc-air battery assembled with CoFe-Co3C@NCNTs-20 cathode shows high power-density (209.15 mW cm−2) and open-circuit voltage (1.505 V). It provides a new reference for promoting the development of bimetallic alloy-coupled transition metal carbide catalysts.

Autocatalytic formed bamboo-like N-doped carbon nanotubes encapsulated with Co nanoparticles as highly efficient catalyst for activation of peroxymonosulfate toward degradation of tetracycline

Co-based catalysts activated peroxymonosulfate (PMS) for organic pollutants degradation has been extensively studied. Co dissolution of Co-based catalysts would result in secondary environmental contamination. Co autocatalysis the formation of bamboo-like N-doped carbon nanotubes to confine Co nanoparticles (Co NPs). Herein, the N-doped carbon nanotubes encapsulated Co (Co@NCTs) were successfully synthesized through a one-step high-temperature calcination method at different temperatures. Co@NCTs-800 exhibited excellent catalytic performance, the degradation efficiency of tetracycline (TC) could reach 94.5% with only 0.05 g/L catalyst in activating PMS. In addition, the encapsulation of carbon nanotubes inhibits the dissolution of Co, the Co2+ dissolution was 0.0594 mg/L in 40 min in the system of Co@NCTs-800/PMS. Free radical quenching tests, electron paramagnetic resonance, and electrochemical measurements revealed that the non-radical route was dominated by tetracycline degradation, with singlet oxygen (1O2) and electron transfer as the principal active species. The N-doped carbon nanotubes can effectively encapsulate Co, which not only reduces the leaching of Co but also play a synergistic role with Co in degrading organic pollutants. In addition to this, the degradation mechanism and pathways of TC were further investigated. The Co@NCTs-800/PMS system was also able to successfully decompose a variety of organic contaminants, demonstrating that it has real application potential in wastewater.

Cobalt nanoparticles decorated bamboo-like N-doped carbon nanotube as nanozyme sensor for efficient biosensing

• Bamboo-like N doped carbon nanotubes encapsulated with cobalt nanoparticles (Co-BNCNTs) was designed by one-step pyrolysis. • The bamboo-like structure could prevent the self-aggregation of the CoNPs, improve the stability of the CoNPs, and enhance the catalytic activity of the CoNPs. • The hollow tubular structure could shorten the distance for the reactants to reach the electrode surface and accelerate the mass transfer process. In this work, Co nanoparticles decorated bamboo-like N-doped carbon nanotubes (Co-BNCNTs) were design, which exhibited excellent oxidase-mimicking activity and could be served as a novel signal amplification platform for dopamine (DA) sensing. Co nanoparticles (CoNPs) encapsulated in bamboo-like N-doped carbon nanotubes (BNCNTs) could prevent their self-aggregation and expose more active sites. Besides, the N-doping in carbon materials could adjust the charge density and increase active sites. Moreover, the synergistic effect between CoNPs and BNCNTs also could contribute to enhance catalytic activity. In a word, excellent electrical conductivity, large electrochemically active area, multiple catalytically active sites are beneficial for DA detection. The Co-BNCNTs/GCE biosensor showed good stability and selectivity, a wide detection range of 0.5-150 μM, and a lower detection limit of 0.0342 μM. The Co-BNCNTs sensor was employed to detect the DA in the actual sample, which displayed a potential application in clinical diagnosis. Furthermore, our study presented an effective way to the synthesis of metal nanoparticles encapsulated into CNTs catalysts as nanozymes for the application in biosensing.

Iron selenide nanoparticles-encapsulated within bamboo-like N-doped carbon nanotubes as composite anodes for superior lithium and sodium-ion storage

Encapsulating the multifunctional nanostructures within a lightweight nanocarbon network is considered to be a promising strategy for developing state-of-the-art electrodes for alkali metal-ion batteries (AMIBs). Herein, the ultrafine FeSe2 nanoparticles (NPs) were encapsulated within the bamboo-like N-doped carbon nanotubes (FeSe2@CNTs) via a rationally in situ self-catalysis and subsequent chemical transformation, realizing a workable capacity and stable architecture. The 3D interactive CNT network provides a fast electron/ion conducting path, and constructs a solid electronic link between the CNTs and FeSe2 NPs. The ultrafine dimension of FeSe2 NPs ensures small volume change and short Li+/Na+ diffusion distance during charge and discharge. Profiting from the fast transport capability of both electrons and ions, the unique FeSe2@CNTs exhibits outstanding host potential for Li+ storage with a capability of 397 mA h g−1 at 10 A g−1. Serving as anode for Na+ storage, the optimized electrode possesses excellent rate capability of 329 mA h g−1 at 8 A g−1. Additionally, the Li+/Na+ storage mechanisms are further revealed by in situ electrochemical techniques and density functional theory (DFT) calculations. The present work inspired a new window for developing high-performance hybrids towards various electrochemical energy applications.

Adina Rubella‐Like Microsized SiO@N‐Doped Carbon Grafted with N‐Doped Carbon Nanotubes as Anodes for High‐Performance Lithium Storage

Microsized silicon oxide (SiO) has become a highly potential anode material for practical lithium‐ion batteries (LIBs) in virtue of its low cost and high capacity. However, its commercialization is still impeded by the low inherent conductivity and nonignorable volume expansion of SiO in the lithiation/delithiation processes. Herein, an in situ catalytic growth approach is developed for grafting N‐doped bamboo‐like carbon nanotubes (NCNTs) onto the polydopamine‐coated SiO microparticles, yielding a unique adina rubella‐like SiO@NC‐NCNT composite. The cross‐sectional scanning electron microscopy images reveal that the flexible middle‐carbon layer plays a crucial role in alleviating volume expansions and improving structural stability of SiO@NC‐NCNTs. Theoretical density functional theory simulation results further prove that the rational construction of ternary heterostructure can effectively balance lithium adsorption energies and greatly improve conductivity of SiO@NC‐NCNTs. As a result, the as‐fabricated SiO@NC‐NCNTs LIB anode shows a high reversible specific capacity of 1103.7 mA h g−1 at 0.2 A g−1 after 200 cycles with a high retention of 99.6% and an outstanding rate capability of 569 mA h g−1 at 5000 mA g−1. The strategy developed herein demonstrates a feasible avenue for developing high‐energy SiO‐based anodes for LIBs.

Aerosol‐assisted synthesis of bimetallic nanoparticle‐loaded bamboo‐like N‐doped carbon nanotubes as an efficient bifunctional oxygen catalyst for Zn‐air batteries

Considering fabrication of highly efficient and low-cost bifunctional oxygen electrocatalysts, which can substitute noble metal-based catalysts, is imperative for advanced rechargeable Zn-air batteries (ZABs). Among the various candidates, N-doped carbon and transition metal composite catalyst is considered as promising bifunctional oxygen electrocatalysts. In this study, one-dimensional structured bamboo-like N-doped carbon nanotubes (bNCNTs) were synthesized by spray pyrolysis followed by a post-treatment. CoFe nanoalloys embedded within SiO2 microspheres were employed as a nanocatalyst to grow homogeneous bNCNTs, which have known as excellent oxygen reduction reaction (ORR) activity. To compensate for the low oxygen evolution reaction (OER) activity of bNCNTs, NiFe nanoparticles were loaded on bNCNTs (NiFe/bNCNT) by a “drop and dry” process and post-treatment. Synergistic effect arising from bNCNTs showing high surface area and controlled infiltration method, NiFe nanoparticles exhibited high dispersity on bNCNTs. Owing to the synergistic effect of NiFe metal nanoparticles and bNCNTs, NiFe/bNCNT exhibited superior ORR properties with a high limiting current density (5.1 mA cm−2) and a low Tafel slope (94 mV dec−1), as well as outstanding OER activity with a low overpotential (350 mV) in an alkaline media compared to those of single metal-loaded bNCNTs and Pt/C-RuO2. Furthermore, when applied as ZAB cathode catalyst, NiFe/bNCNT demonstrated a high power density (224 mW cm−2) and 330 hours long cycling stability.

CoFe alloy embedded in N-doped carbon nanotubes derived from triamterene as a highly efficient and durable electrocatalyst beyond commercial Pt/C for oxygen reduction

For development of green and sustainable energy, it is of importance to search highly efficient and low-cost electrocatalysts of oxygen reduction reaction (ORR) in energy conversion devices. Herein, CoFe alloyed nanocrystals embedded in N-doped bamboo-like carbon nanotubes (CoFe@NCNTs) were facilely synthetized by one-step co-pyrolysis with the mixture of triamterene, metal chlorides and graphitic carbon nitride (g-C3N4). The resultant CoFe@NCNTs exhibited excellent ORR activity with the positive shifts in the onset potential (Eonset = 0.97 V) and half-wave potential (E1/2 = 0.88 V), outperforming commercial Pt/C (Eonset = 0.96 V; E1/2 = 0.84 V). Compared to metal organic frameworks (MOFs)-based strategy for synthesis of low-cost carbon-based ORR catalysts, this method is simple and convenient, coupled by avoiding the complicated synthesis of MOFs and its ligands. This work provides a promising route to fabricate advanced transition-metal-based carbon catalysts in the researches correlated with energy conversion devices.

Insight on the active sites of CoNi alloy embedded in N-doped carbon nanotubes for oxygen reduction reaction

Transition metal alloy electrocatalysts have sparked intense interest for their use in oxygen reduction reaction (ORR). However, there is almost no corresponding research on the alloy active sites. In this study, CoNi alloy nanoparticles embedded in bamboo-like N-doped carbon nanotubes (CoNi-NCTs) as catalysts constructed by a facile pyrolysis of Prussian blue analogs were investigated. The density functional theory calculation reveals that the oxygen molecules are more easily adsorbed on the Ni sites in these catalysts, while the Co sites favor the formation of OOH⋆ intermediates during ORR. In addition, the cooperation of the CoNi alloys with the N-doped carbon benefits electron transfer and promotes electrocatalytic activity. The optimized CoNi-NCT shows remarkable ORR catalytic activity with an half-wave potential (E1/2) of 0.83 V, an onset potential (Eonset) of 0.97 V, and superior durability, all of which surpass the commercial Pt/C catalysts. The assembled zinc-air battery delivers a small charge/discharge voltage gap of 0.86 V at 10 mA cm−2, a high-power density of 167 mW cm−2, and good stability (running stably over 900 cycles).

Highly electrocatalytic performance of bimetallic Co–Fe sulfide nanoparticles encapsulated in N-doped carbon nanotubes on reduced graphene oxide for oxygen evolution

We rationally design and construct a heterostructured hybrid with reduced graphene oxide served as a platform to in-situ grow N-doped bamboo-like carbon nanotubes encapsulating bimetallic Co–Fe sulfide nanoparticles through a two-stage pyrolysis succeeded by an evaporating sulfurization process (denoted as CoxFe1-xS2@N-CNTs/rGO). By tuning the Co/Fe ratio, the optimal Co0.6Fe0.4S2@N-CNTs/rGO exhibits a remarkable oxygen evolution reaction (OER) performance in 1.0 M KOH, in which the overpotential at 10 mA cm−2 and Tafel slope are recorded as 248 mV (vs. RHE) and 58.3 mV dec−1, respectively, outmaneuvring commercial RuO2 and most Co/Fe sulfide-based catalysts in recent peer reports. Comprehensive experiment results unravel that the outstanding OER electrocatalytic performance owes to the reinforced synergy between CoS2 and FeS2, the heterostructures constituted by partial CoS2 and FeS2, the confining effect of N-CNTs/rGO for CoS2 and FeS2 nanoparticles, and the high conductivity and large surface of N-CNTs/rGO.

Fe3C-inserted “tube plugging into porous network” nanohybrids as advanced sulfur hosts for lithium-sulfur batteries

Commercial applications of lithium-sulfur batteries are hindered by the low electrical conductivity of sulfur cathodes, which can be overcome by the application of suitable sulfur host materials. In this work, a novel and effective method is developed to grow bamboo-like N-doped carbon nanotubes (NCNTs) across three-dimensional N-doped porous carbon network (NPCNs) via chemical vapor deposition, thereby successfully preparing the sulfur-loaded composite carbon material inserted into the porous network. In such structure, carbon nanotubes act as electronic conduction paths, carbon networks as mass transfer channels, as well as the inserted Fe3C nanoparticles can increase the polarity of the carbon matrix. The discharge capacity of the S-NCNT/NPCNs cathode, as high as 1125 mAh g−1 at 0.2 C, retains 43.5% of its value when the current is increased 10-fold to 2 C. A specific capacity of 548.1 mAh g−1 at 1 C remains almost unchanged after 300 cycles, demonstrating better charge and discharge performance and excellent cycling ability of these promising candidate materials for Li-S battery applications. More importantly, the synthesis strategy is universal and can be fully extended to prepare other units, even binary NCNT/NPCNs (for example, NCNT/NPCNs-Co, NCNT/NPCNs-Co-Fe, NCNT/NPCNs-Fe-Ni, and NCNT/NPCNs-Co-Ni). The new strategy provided here may open up new ways for the application of hybrid carbon nanostructures in energy storage systems.

Rationally constructing CoO and CoSe2 hybrid with CNTs-graphene for impressively enhanced oxygen evolution and DFT calculations

Constructing CoO–CoSe2 heterostructures through partial selenization of CoO is proposed to ameliorate the electrocatalytic performance of Co-based compounds toward oxygen evolution reaction (OER). Moreover, with reduced graphene oxide as a platform to in-situ grow N-doped bamboo-like carbon nanotubes encapsulating part of CoO and CoSe2 nanoparticles, we fabricated a novel hybrid (denoted as CoO–CoSe2@N-CNTs/rGO) via a combination of two-stage calcination and subsequent selenization treatment. As an OER electrocatalyst in 1.0 M KOH, CoO–CoSe2@N-CNTs/rGO affords low overpotentials (250 [email protected] mA cm−2 and 322 [email protected] mA cm−2), favorable kinetics (a Tafel slope of 68 mV dec−1), and excellent durability, outperforming commercial RuO2 and most Co-based electrocatalysts reported till date. Comprehensive experiment results uncover that the exceptional electrocatalytic performance mainly emanates from the synergistic effect between CoSe2 and CoO in heterostructure, N doping effect in CNT and rGO, and the confining effect of N-CNTs and rGO for CoO–CoSe2, resulting in more active sites and enhance conductivity. More importantly, density functional theory calculations disclose that the concurrent N doping and desirable encapsulation of the CoO–CoSe2 nanoparticle in N-CNT can optimize the adsorption energies of OER intermediates and increase the electric conductivity, thereby expediting the OER. This work is helpful to foster understanding on the structure–performance correlations of electrocatalysts with multi-active sites and multi-components for diverse applications.

Self-Reconstruction of Co/Co2P Heterojunctions Confined in N-Doped Carbon Nanotubes for Zinc–Air Flow Batteries

The development of highly efficient, stable, and low-cost catalysts for oxygen reduction and evolution reactions (ORR and OER, respectively) is vital for rechargeable metal–air batteries and united regenerative fuel cells. Herein, we develop a facile strategy for fabricating the heterojunction Co/Co2P nanocrystals that are confined in bamboo-like N-doped carbon nanotubes (Co/Co2P@NCNTs) on a large scale. In particular, operando X-ray absorption spectroscopy and electrochemical measurements were conducted to investigate the dynamic structural evolution of the precatalyst during electrocatalytic operation. Active state self-reconstruction from the Co/Co2P heterojunctions into Co3+ octahedral site (Oh)-containing CoOx(OH)y active species is observed. Consequently, the high degree of graphitization of NCNTs with optimized N species and the completely triggered cross-linked CoOx(OH)y both contribute to the outstanding bifunctional ORR/OER activity (Egap = 0.68 V vs RHE) and durability. Meanwhile, the Co/Co2P@NCNTs as a precatalyst exhibits an ultralong cycling stability (cycling life of >1000 h) in rechargeable zinc–air flow batteries.

An electrochemical immunosensor coupling a bamboo-like carbon nanostructure substrate with toluidine blue-functionalized Cu(ii)-MOFs as signal probes for a C-reactive protein assay.

In this paper, a novel sandwich immunosensor based on a toluidine blue (Tb) loaded metal organic framework (Cu(ii)-HKUST-1/Tb) as the signal element and a nitrogen-doped 3D carbon nanostructure as the electrode substrate was constructed for the detection of C-reactive protein (CRP). Tb as an electrochemically active agent usually forms a polymer by aggregation in the solvent, causing a poor electrochemical response. Therefore, in order to overcome this obstacle, Cu(ii)-HKUST-1 with a porous nanostructure and large specific surface area as a carrier could adsorb a large number of Tb molecules on its surface to improve its electrochemical performance. In addition, the high electron transfer efficiency of the N-doped bamboo-like carbon nanotubes (CoFe/N-GCT) improves the sensitivity of the biosensor. Differential pulse voltammetry (DPV) was used to detect the current signal of Tb at −0.2 V. The current response increased with the increase in concentration of CRP, ranging from 0.5 to 200 ng mL−1. The detection limit is 166.7 pg mL−1 (S/N = 3). Moreover, the proposed biosensor can be applied in real serum sample detection. It has potential applications in the field of biomedicine assays.

Morphological and reactive optimization of g-C3N4-derived Co,N-codoped carbon nanotubes for hydrogen evolution reaction

Scheme for the synthesis of bamboo-like N-doped carbon nanotubes.

Cobalt encapsulated in bamboo-like N-doped carbon nanotubes for highly sensitive electroanalysis of Pb(II): enhancement based on adsorption and catalysis.

Carbon nanotubes (CNTs) are recognized as desirable candidates to fabricate electrochemical sensing interfaces owing to their high surface area and excellent electron conductivity. However, the poor catalytic properties of CNTs significantly hinder their further application in electrochemical detection. Herein, for the first time we combined defective CNTs with catalytically active cobalt nanoparticles (Co NPs) to give cobalt encapsulated in a bamboo-like N-doped carbon nanotube nanocomposite (Co/N-CNTs). The novel constructed Co/N-CNTs are used as a modifier on a bare glass carbon electrode for the electrochemical detection of Pb(ii). As a result, the positive effect of adsorption and catalysis on Co/N-CNT shows a significant improvement in the electroanalytical performance towards Pb(ii) with a sensitivity of 69.74 μA μM-1 and a limit of detection of 0.039 μM. Moreover, the stability and practical applications of Co/N-CNTs towards Pb(ii) in real water samples obtained from a mining subsidence area were also considered. This method shows great promise, achieving an outstanding electroanalysis efficiency with noble-metal-free nanocomposite sensors based on the combination of carbon and transition metals.

Uniform Bamboo-like N-Doped Carbon Nanotubes Derived from a g-C3N4 Substrate Grown via Anchoring Effect to Boost the Performance of Metal–Air Batteries

Electrocatalysts for oxygen reduction reaction (ORR) are the most critical components in many renewable and sustainable “green” energy storage and conversion technologies, such as metal–air batteri...

Golden Bristlegrass-Like Hierarchical Graphene Nanofibers Entangled with N-Doped CNTs Containing CoSe2 Nanocrystals at Each Node as Anodes for High-Rate Sodium-Ion Batteries.

Golden bristlegrass-like unique nanostructures comprising reduced graphene oxide (rGO) matrixed nanofibers entangled with bamboo-like N-doped carbon nanotubes (CNTs) containing CoSe2 nanocrystals at each node (denoted as N-CNT/rGO/CoSe2 NF) are designed as anodes for high-rate sodium-ion batteries (SIBs). Bamboo-like N-doped CNTs (N-CNTs) are successfully generated on the rGO matrixed nanofiber surface, between rGO sheets and mesopores, and interconnected chemically with homogeneously distributed rGO sheets. The defects in the N-CNTs formed by a simple etching process allow the complete phase conversion of Co into CoSe2 through the efficient penetration of H2 Se gas inside the CNT walls. The N-CNTs bridge the vertical defects for electron transfer in the rGO sheet layers and increase the distance between the rGO sheets during cycles. The discharge capacity of N-CNT/rGO/CoSe2 NF after the 10 000th cycle at an extremely high current density of 10 A g-1 is 264 mA h g-1 , and the capacity retention measured at the 100th cycle is 89%. N-CNT/rGO/CoSe2 NF has final discharge capacities of 395, 363, 328, 304, 283, 263, 246, 223, 197, 171, and 151 mA h g-1 at current densities of 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 A g-1 , respectively.