Hollow Carbon Tubes Research Articles

Multi-heteroatom-doped hollow carbon tubes as robust electrocatalysts for the oxygen reduction reaction, oxygen and hydrogen evolution reaction

Multi-heteroatoms-doping tunes the electronic structure of the catalyst, thereby optimizing the intrinsic catalytic activity of tri-functional metal-free electrocatalyst. • This work provides a self-sacrifice template engineering strategy to synthesize NSCHCT as tri-functional metal-free electrocatalyst. • NSCHCT shows an excellent bifunctional performance towards ORR/OER and has a small ORR/OER voltage difference of 0.85 V. • The hollow hierarchical porous structure and multi-heteroatom-doped provide rich reactive sites. • ZAB based on NSCHCT1000 displays long-term stability of 55 h, which can drive a LED. Developing non-noble metal-based electrocatalysts for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) is highly desirable, while still facing challenges. Herein, a self-sacrifice template engineering strategy that feasible carbonization of the copolymer of melamine-trithiocyanurim wrapped by polydopamine was developed to fabricate N, S hollow co-doped carbon tube (NSCHCT) based trifunctional electrocatalyst. Owing to the hierarchical structure, including hollow and porous structure, the obtained catalyst exhibits rich active sites and favourable mass transfer advantage, boosting the kinetic of the catalytic process. Moreover, multiple heteroatoms-doping provides various active sites. Notably, the thiophene sulfur combining with pyridinic N(p-N/S) and thiophene sulfur combined with graphitic N (g-N/S) shows the lowest activation energy barrier for OER/ORR and HER, respectively. As a result, the NSCHCT assembled Zinc-air battery shows excellent performance with a power density of 109 mW cm −2 and a high open-circuit voltage of 1.44 V, comparable with the Pt/C + RuO 2 system.

N-Doped Hollow Carbon Tubes Derived N-HCTs@NiCo2O4 as Bifunctional Oxygen Electrocatalysts for Rechargeable Zinc-Air Batteries

It is paramount important to design and explore excellent bifunctional oxygen electrocatalysts to conquer or weaken the shortcomings encountered by Zinc-air batteries at present. Herein, a novel N-doped hollow carbon tubes modified by uniform NiCo2O4 nanocrystals (N-HCTs@NiCo2O4), has been developed as an extremely efficient bifunctional catalyst. The hollow structure of N-HCTs possesses a large specific surface area of 610.60 cm g-1 which provides abundant active N-dopant sites for the oxygen reduction reaction, whereas the NiCo2O4 nanocrystals serve as the positive phase for the oxygen evolution reaction. It is found that the efficient bifunctional activity is obtained by establishing a coupling interface between N-HCTs and NiCo2O4. The N-HCTs@NiCo2O4 composite has a half-wave potential of 0.81 V toward ORR and the overpotential of 330 mV at a current density of 10 mA cm-2 toward OER as compared with noble metal catalysts. The N-HCTs@NiCo2O4 as the cathode catalyst for Zinc-air batteries exhibits superior peak power density (150 mW cm-2), specific capacity up to 779 mAh g-1, and good stability even after 100 h of cyclic charge/discharge cycles N-HCTs@NiCo2O4 has good prospects for practical applications of non-precious metal catalysts in the cathode of Zinc-air batteries.

Heteroatom-doped hollow carbon micro-tube derived from platanus catkins fiber for sodium ion supercapacitor

Heteroatom-doped hollow carbon micro-tubes are successfully fabricated from platanus catkins fibers by simply precarbonization and then KOH activation method for sodium ion supercapacitor. The different activation temperatures (600 °C, 700 °C and 800 °C) are used to study the effect on the structural and electrochemical performance of the bio-carbon materials. As the activation temperature increases, the disorder degrees and the surface (inner and outer) roughness of the as-prepared hollow carbon tubes (with diameters of about 15–25 μm and a wall thickness around 2–3 μm) increase. Benefiting from the proper numerous pores (micro-, meso- and macro-pores), high specific surface area, unique structure and heteroatom (N and O) dual doping, hollow carbon micro-tubes activated at 700 °C exhibit superior electrochemical performance with good rate capability and high specific capacity of 195, 140, 112, 95 and 84 mAh/g at the current densities of 0.1, 0.2, 0.5, 1 and 2 A/g, respectively.

Growing NiS2 nanosheets on porous carbon microtubes for hybrid sodium-ion capacitors

NiS2 is a promising anode material for sodium-ion batteries (SIBs) and capacitors (SICs). However, the sluggish Na+ diffusion and large volume change of bulk NiS2 during sodiation/de-sodiation lead to poor rate capability and fast capacity decay, limiting its practical application. Herein, we design and prepare well-oriented NiS2 nanosheets on porous carbon microtubes (denoted as NiS2/pCMT) as a novel anode material for SIBs/SHCs. The unique porous hollow carbon tubes and NiS2 nanosheets can well relieve the repeated stress/strain and maintain the structural integrity of the composite anode during long-term charging/discharging. As a confirmation, a modelled SHC is constructed by using the NiS2/pCMT composite as anode and coupling with an activated carbon cathode, delivering a high energy density of 136 Wh kg−1 and good cycling stability. The first-principles density functional theory (DFT) calculations confirm that the NiS2 nanosheets surface has a high chemical affinity towards Na+ ions, promising the concentration of Na+ ion on/nearby the surface for fast redox reactions during sodiation/de-sodiation of NiS2. This work provides some new insights for the design and fabrication novel composite electrode materials for applications in beyond lithium-ion batteries/capacitors.

3D heterogeneous CTF@TiO2/Bi2WO6/Au hybrid supported by hollow carbon tubes and its efficient photocatalytic performance in the UV-vis range

The 3D heterogeneous CTF@TiO2/Bi2WO6/Au hybrid broadens the absorption over the entire visible range and improves electron–hole separation.

Rebuilding supramolecular aggregates to porous hollow N-doped carbon tube inlaid with ultrasmall Ag nanoparticles: A highly efficient catalyst for CO2 conversion

Fabrication of novel heterogeneous catalysts with well-designed structures is unusually intriguing for CO2 conversion. In this study, we have prepared a porous hollow N-doped carbon tube through the pyrolysis of self-assembled melamine cyanurate aggregate supramolecular precursor. Ultrasmall Ag nanoparticles were tightly anchored in the hollow N-doped carbon tube via an in-situ fabrication. The average size of Ag nanoparticles was confined in only 2.19 nm with the assistance of abundant surface functional groups and porous structures. Additionally, inherent hollow N-doped carbon tube structure could prevent nanoparticles aggregating and leaching; also, they facilitated gas adsorption and mass transfer in CO2 catalysis. Due to their remarkable properties, the novel material was utilized as heterogeneous catalyst for the carboxylation of alkynes with CO2, and exhibited outstanding catalytic activity and stability at ambient pressure and low temperature.

Coral-like hierarchical structured carbon nanoscaffold with improved sensitivity for biomolecular detection in cancer tissue

The development of flexible microelectrodes with large surface area and high activity has currently attracted enormous research interest for its promising use in in vitro and in vivo monitoring various physiological behaviors. Inspired by the unique morphological and structural features of dendritic coral, a coral-like hierarchical nanohybrid of carbon nanospheres (GNSs) wrapped hollow carbon tubes (HCT) has been designed and modified on flexible activated carbon fiber (ACF) microelectrode for sensitive electrochemical detection of biomarker in live cells and cancer tissue. The hierarchical nanohybrid microelectrode was fabricated by a novel dual-template strategy using ZnO nanorod arrays as the hard template and poly-glucose microspheres as both self-template and carbon source, which results in the formation of coral-like structured carbon nanoscaffold integrated with GNSs wrapped HCT hybrids (HCT@GNSs) on ACF substrate for homogeneous interfacial contacts and reaction. The as-obtained HCT@GNSs modified ACF (HCT@GNSs/ACF) microelectrode exhibits high specific surface area and good stability, and serves as an ideal support for anchoring functional nanomaterials. In order to improve the electrochemical activity of the modified microelectrode, HCT@GNSs has been decorated with dense and ultrafine Pt nanoparticles (PtNPs). Benefiting from the hierarchical feature of HCT@GNSs and uniformly distribution of electroactive PtNPs, the PtNPs decorated HCT@GNSs/ACF microelectrode demonstrates good electrochemical sensing performance toward H2O2, which enable the operating electrochemical platform be used for real-time tracking H2O2 generated from different types of live cells and in situ sensitive detection of H2O2 in cancer tissue from laboratory mice.

Engineering of Co9S8–CoS nanoparticles encapsulated into N-doped graphitic carbon tubes for high-performance lithium storage

Sulfide/carbon composites are promising anode candidates for lithium-ion batteries owing to the synergy of the two components. Their electrochemical performances are highly dependent on their structures. Herein, Co9S8–CoS nanoparticles encapsulated into N-doped graphitic carbon tubes (Co9S8–CoS/NGCT) are synthesized by a controllable in-situ self-assembly method assisted by a freeze-drying process. The hollow carbon tubes with a thin wall have an enough interior void space, which can effectively accommodate the volume expansion and prevent the aggregation of Co9S8–CoS nanoparticles during cycling. Moreover, benefiting from high specific surface area and efficient electron transport pathways, pseudocapacitive-controlled process accounts for a large proportion in the electrochemical lithium storage of Co9S8–CoS/NGCT. As a result, the Co9S8–CoS/NGCT shows a high specific capacity (1004 mAh g−1 at 0.1 A g−1 after 150 cycles), good cycling stability (517 mAh g−1 at 1 A g−1 after 1000 cycles) and excellent rate capability (410 mAh·g−1 at 5 A g−1).

Porous hollow carbon tube derived from kapok fibres as efficient metal-free oxygen reduction catalysts

Pyrogenic biomass carbon has been deemed a promising alternative to Pt/C for the oxygen reduction reaction (ORR) owing to its low cost, excellent activity, and eco-friendly properties. Herein, a porous carbon tube material derived from kapok fibres was prepared by combining activation with pyrolysis. Electrochemical measurements demonstrated that the kapok fibre-derived material prepared at 900°C had excellent ORR performance with a half-wave potential –0.14 V (vs. Ag/AgCl) close to that of commercial Pt/C (–0.13 V vs. Ag/AgCl) in 0.1 mol L–1 KOH. The prepared material also displayed remarkable methanol tolerance and durability. Furthermore, the maximum power density output of the microbial fuel cell using the prepared material was (801± 40) mW m–2, comparable to that of the Pt/C cathode ((778± 31) mW m–2). The present work provides a facile way of using economical and renewable biomass to develop a porous structure and high-activity cathode ORR catalyst for fuel cell applications.

Urea-bridging synthesis of nitrogen-doped carbon tube supported single metallic atoms as bifunctional oxygen electrocatalyst for zinc-air battery

Single atom (SA) catalysts have recently emerged as promising candidates to substitute noble metals catalysts. Herein, a urea-bridge method has been exploited to fabricate stable metallic single atom dispersed on nitrogen-doped carbon tubes. The preparation involved a facile pyrolysis of ellagic acid (EA)-metal coordination compound mediated through the usage of urea. During the synthesis process, urea acted as a bridge to drive the formation of hollow carbon tube as well as to provide N sites to immobilize SA in a space-confined environment. The active SA sites together with the accessibility and rapid mass transport from the hollow substrate endowed the obtained EA-SAs (e.g. EA-Co-900, EA-Ni-900) outstanding performances in oxygen reduction/evolution reactions. Furthermore, EA-Co-900 showed a high power density (e.g. 73 mW cm−2, at 65 mA cm−2) and excellent durability of 110 h at 20 mA cm−2 when assembled into rechargeable zinc-air batteries.

Encapsulating segment-like antimony nanorod in hollow carbon tube as long-lifespan, high-rate anodes for rechargeable K-ion batteries

K-ion battery (KIB) is a new-type energy storage device that possesses potential advantages of low-cost and abundant resource of potassium. To develop advanced electrode materials for accommodating the large size and high activity of potassium ion is of great interests. Herein, a segment-like antimony (Sb) nanorod encapsulated in hollow carbon tube electrode material (Sb@HCT) was prepared. Beneficial from the virtue of abundant nitrogen doping in carbon tube, one-dimensional and hollow structure advantages, Sb@HCT exhibits excellent potassium storage properties: in the case of potassium bis(fluorosulfonyl)imide (KFSI) electrolyte, Sb@HCT displays a reversible capacity of up to 453.4 mAh·g−1 at a current density of 0.5 A·g−1 and good rate performance (a capacity of 211.5 mAh·g−1 could be achieved at an ultrahigh rate of 5 A·g−1). Additionally, Sb@HCT demonstrates excellent long-cycle stability at a current density of 2 A·g−1 over 120 cycles. Meanwhile, electrolyte optimization is an effective strategy for greatly improving electrochemical performance. Through ex-situ characterizations, we disclosed the potassiation of Sb anode is quite reversible and undergoes multistep processes, combining solid solution reaction and two-phase reaction.

Nitrogen-Doped Hollow Mesoporous Carbon Tube for Supercapacitors Application

Hollow mesoporous carbon tube with high specific surface area are widely used in supercapacitors due to their length-diameter ratio, unique tubular structures, low density, fast ionic diffusion and good electrical conductivity. Herein, N-doped hollow mesoporous carbon tube (HMCT) were prepared via electrostatic assembly approach by using MnO2 rods as the templates, resorcinol/formaldehyde (RF) as the carbon precursor, tetraethyl orthosilicate (TEOS) as pore-forming agents, ethylenediamine (EDA) as the base catalyst and nitrogen precursor. The obtained N-doped HMCT replicates the morphology of MnO2 and has a uniform hollow tubular structure. The addition of TEOS creates rich mesoporous on the shell which greatly improves the surface area. In addition, EDA is not only a catalyst for resin polymerization and TEOS hydrolysis, but also a nitrogen precursor that leads to in situ N-doping in the HMCT framework. An electrode made of this material exhibits a specific capacitance of 307 F g−1 at 1 A g−1 and excellent rate performance (78.2% retention ratio at 20 A g−1). Furthermore, N-doped HMCT based two-electrode system possesses energy density of 72.4 Wh kg−1 at a power density of 3.2 KW kg−1 in the wide voltage range of 1.6 V, exhibiting its potential for electrode materials with high performance.

Self‐Sacrificial Template Synthesis of a Nitrogen‐Doped Microstructured Carbon Tube as Electrocatalyst for Oxygen Reduction

AbstractThe development of low‐cost, efficient and stable electrocatalysts for the oxygen reduction reaction (ORR) is desirable but remains a great challenge. We report a self‐sacrificial template synthesis approach for nitrogen‐doped hollow carbon microtubes as electrocatalyst for ORR. Typically, Fe‐MIL (Materiaux de l'Institute Lavosier) nanocrystals cast as self‐sacrificial template. Polyaniline (PANI) was in situ‐synthesized and deposited on the surface of Fe‐MIL nanocrystals. By a two‐step pyrolysis of the MIL‐101 (Fe)@PANI hybrids, unique microstructured carbon tubes with Fe3O4 nanoparticles encapsulated inside the wall were fabricated after the self‐sacrificial template decomposed. The optimized C‐PANI‐MIL‐2 catalyst exhibits a high onset potential of 1.0 V in alkaline media. Out of the negative effect of the disruption of metal‐organic frameworks (MOF) morphology, the ingenious catalytic activities may be ascribed to the well‐defined microtube architecture with a high accessible surface area, the existence of FeN2+2/FeN4 and rich active nitrogen atoms. Moreover, C‐PANI‐MIL‐2 exhibited excellent methanol tolerance and durability compared to a commercial Pt/C catalyst in both electrolytes. This work may provide a new strategy for the design and preparation of microstructured non‐precious metal based catalysts supported on hollow carbon tubes for fuel cells.

Supramolecular Assembly Templated Nitrogen-Doped Hollow Carbon Tubes as Highly Active and Durable Catalytic Support for Methanol Electrooxidation

A supramolecular polymerization-assisted approach is proposed for the preparation of 1D hollow nitrogen-doped carbon tubes (h-NCTs) as an advanced support material to immobilize metal nanoparticles...

1D N-doped hierarchically porous hollow carbon tubes derived from a supramolecular template as metal-free electrocatalysts for a highly efficient oxygen reduction reaction

1D hollow nitrogen-doped carbon tubes (h-NCTs) were fabricated through a supramolecular template-derived approach and employed as the structure-guiding template, porogen and nitrogen source for in situ N-doping.

Biomass-derived nitrogen and boron dual-doped hollow carbon tube as cost-effective and stable synergistic catalyst for oxygen electroreduction

Low-cost and highly active catalysts for oxygen reduction reaction (ORR) were of great importance to the development of fuel cell. Herein, we presented a novel N/B co-doped carbon as cost-effective and stable ORR catalyst from renewable biomass. The as-prepared carbon showed an interesting hollow tube morphology that derived from its precursor. The N/B co-doped sample (NB-HCT) possessed bigger electrochemical active area (296.4m2g−1), and also contained much more ORR active-N/B species than those of single N or B doped carbon. Notability, the on-set potential and half-wave potential of NB-HCT were 0.929V (vs. RHE) and 0.810V (vs. RHE), respectively, which were much more positive than others and even comparable to Pt/C, revealing it had distinct ORR activity. Remarkably, the superior ORR activity of NB-HCT could be mainly ascribed to the synergistic effect of ORR active-N and B-C, which might result in the possible formation of high-active B-C-N nanostructure. Therefore, NB-HCT should be one of promising ORR catalysts to alternative precious Pt/C and promote the development of fuel cell.

Shape-Persistent Graphite Replica of Metal Wires.

A facile one-step procedure for a template-assisted fabrication of hollow carbon tubes is reported, using organic halides as the carbon source. The shape-persistent tubes are obtained with arbitrary shapes as hollow replicas of the metal template. They feature a high quality of graphite, and a high conductivity of 1.31 ± 0.05 · 106 S·m-1 .

Template-free and one-pot synthesis of N-doped hollow carbon tube @ hierarchically porous carbon supporting homogeneous AgNPs for robust oxygen reduction catalyst

Porous C/Ag nanohybrids were one type of emerging and promising alternative oxygen reduction catalysts for Pt, which was crucial to energy conversion and storage devices. Herein, a template-free, sustainable and in-situ method was employed for preparing N-doped hollow carbon tube @ hierarchically porous carbon supporting homogeneous Ag nanoparticles (HCT@HPC@AgNPs) by one-pot carbonization with the assist of “chelating effect”. It was very interesting that the “chelating effect” can inhibit the self-aggregation of AgNPs during its growing process, since Ag+ can be well immobilized on precursor. Moreover, during the carbonization process, an amazing N-doped hollow carbon tube @ porous carbon was also achieved by the synergistic effect of thermal degradation, spontaneous bubble-template and self-doping. The resultant HCT@HPC@AgNPs was investigated by physical characterizations and electrochemical tests. The results indicated that HCT@HPC@AgNPs delivered distinct electrocatalytic activity towards oxygen reduction reaction (ORR), long-term durability and anti-toxic capacity in alkaline electrolyte, which was comparable or even better than Pt/C. Thus, HCT@HPC@AgNPs was a promising ORR catalyst for application in the field of energy and catalysis.

High-throughput Acid-Base Tandem Organocatalysis over Hollow Tube-Shaped Porous Polymers and Carbons

A FeCl3 mediated polymerization of 4-tritylaniline with dimethoxymethane (DMM) at 80 oC resulted the formation of hollow tube shaped porous polymers, which can be transformed into microflowers and larger hollow tubes (bamboo shaped) by increasing the amount of DMM during the synthesis. All polymers are converted to Microporus hollow carbon tubes (CT), carbon flowers (CF), extra-large carbon hollow tubes by simply pyrolyzing it at 600–700 oC under N2 atm. Among them only CTs having smaller dimension of hollow tubes, exhibits better CO2 uptake (120 cm3 g−1, 273 K) at 1 atm, higher than other microporous organic tubes. A one pot acid-base tandem organocatalysis has been carried out over these N-doped CT, CF and amine functionalized polymers after post grafting with –SO3H groups for the synthesis of 3-benzylidine malononitrile.

Engineering Empty Space between Si Nanoparticles for Lithium-Ion Battery Anodes

Silicon is a promising high-capacity anode material for lithium-ion batteries yet attaining long cycle life remains a significant challenge due to pulverization of the silicon and unstable solid-electrolyte interphase (SEI) formation during the electrochemical cycles. Despite significant advances in nanostructured Si electrodes, challenges including short cycle life and scalability hinder its widespread implementation. To address these challenges, we engineered an empty space between Si nanoparticles by encapsulating them in hollow carbon tubes. The synthesis process used low-cost Si nanoparticles and electrospinning methods, both of which can be easily scaled. The empty space around the Si nanoparticles allowed the electrode to successfully overcome these problems Our anode demonstrated a high gravimetric capacity (~1000 mAh/g based on the total mass) and long cycle life (200 cycles with 90% capacity retention).