Porous Carbon Microtubes Research Articles

Leveraging porosity and morphology in hierarchically porous carbon microtubes for CO2 capture and separation from humid flue gases

Leveraging porosity, surface chemistry and morphology of porous carbons play a critical role in CO2 capture performance. However, the effective and sustainable synthesis of porous carbons with well-interconnected hierarchical pore structure, high-proportioned micropores and high yield remains a huge challenging by a mild one-step chemical activation without damaging the natural unique nanostructure. Here, we proposed a green and sustainable strategy to fabricate porous carbons with tailorable porosity and unique tubular structure by an inorganic dynamic porogen of CuCl2. The dynamic activation mechanism of CuCl2 was explored in detail. In particular, the hierarchical porosity with a high-proportioned narrow micropores can be finely tuned without sacrificing the natural tubular morphology. Importantly, the resultant porous carbon adsorbents have an excellent resistance to water vapor, which can capture CO2 from humid flue gases with satisfactory adsorption capacity and selectivity. The HPCM-3 can achieve the best CO2 uptakes of 4.05 and 2.05 mmol/g under 100 kPa at 25 and 50 °C, respectively. Such superior CO2 adsorption behaviors can be well maintained even at high humidity of 70 %, and hardly decay with the enhancement of humidity. This route provides a promising avenue for developing the practical trace CO2 carbon-based adsorbents on a large scale to sieve CO2 from humid flue gases.

Preparation of aligned porous carbon microtubes by a reactant permeation template method and the highly selective adsorption of methylene blue dye from wastewater

Selective adsorption was beneficial to the separation and recovery of valuable dyes and highly efficient resource utilization. Modified aligned porous carbon microtubes (MAPCTs) in centimeter scale were prepared by a novel reactant permeation template method without addition of pore former. In a solution of pH 8, MAPCTs showed excellent adsorption capacity for cationic dye methylene blue (MB), which reached 1875.4 mg/g when the initial concentration of MB increased to 200 mg/L. The adsorption process was fitted by isotherm model and kinetic model. In addition, MAPCTs could selectively separate MB from cationic dye rhodamine B (RhB) or anionic dye methyl orange (MO) mixture solutions, because the reactant permeation template method well controlled the characteristics of the pores. The separation efficiency for MB/RhB and MB/MO solutions was 99.7 %. The adsorbed MB could be efficiently regenerated from the recycled MAPCTs and the adsorption–desorption could be repeated for at least 5 times, keeping the regeneration efficiency 98 %. The selective adsorption and separation process could follow a diffusion limitation and size exclusion mechanism and an electrostatic repulsion mechanism. Since the reactant permeation template method can be easily used for industrial mass production of MAPCTs, this method and MAPCTs have great potential for recycling MB from industrial wastewater.

Reactive Template-Engaged Synthesis of NiSx/MoS2 Nanosheets Decorated on Hollow and Porous Carbon Microtubes with Optimal Electronic Modulation toward High-Performance Enzyme-like Performance

As a promising cost-effective nanozyme, MoS2 nanosheets (NSs) have been considered as a good candidate for the enzyme-like catalysis. However, their catalytic activity is still restricted by the insufficient active sites and poor conductivity, and thus, the comprehensive performances are still unsatisfactory. To address these issues, herein, we design and fabricate an intelligent tubular nanostructure of hierarchical hollow nanotubes, which are assembled by NiSx/MoS2 NSs encapsulated into N-doped carbon microtubes (NiSx/MoS2@NCMTs). The N-doped carbon microtubes (NCMTs) serve as a conductive skeleton, integrating with NiSx/MoS2 NSs and ensuring their well-distribution, thereby maximally exposing more active sites. Additionally, the tube-like structure is favorable for increasing the mass transfusion to ensure their excellent catalytic performance. Profiting from their component and structural advantages, the obtained NiSx/MoS2@NCMTs exhibit a surprisingly enhanced enzyme-like activity. Based on these, a facile colorimetric sensing platform to detect H2O2 and GSH has been developed. This proposed approach can be expected to synthesize a series of tubular heterostructured MoS2-based composites, which will be widely applied in catalysis, energy storage, disease diagnosis, etc.

Green fabrication of hierarchically porous carbon microtubes from biomass waste via self-activation for high-energy-density supercapacitor

Developing high-efficiency electrode materials is always desired for supercapacitor, in order to improve the energy density. Herein, we found that hierarchically porous carbon microtubes (HPCMTs) derived from plane tree fruit fluff via self-activation method demonstrated prominent supercapacitor performance as electrode materials, since they possessed hierarchical pore structure consisting of abundant micro- and mesopores, high specific surface area (SSA) and good wettability with electrolyte. The HPCMT-1100-6 with the largest SSA (2805 m2/g) and maximal total pore volume (1.98 cm3/g) was obtained at 1100 °C with dwelling time of 6 h. The HPCMT-1100-6-based cell in organic electrolyte showed an ultrahigh energy density of 46.3 Wh/kg at high power density of 1106 W/kg in 1.0 M TEABF4/AN, as well as splendid rate capability and impressive long-term cyclic stability. The energy density still can retain 35 Wh/kg even at an ultrahigh power density of 83.8 kW/kg, the capacitance retention maintains 96.4% after 10000 cycles at a current density of 10 A/g. This study provided a novel practical sustainable strategy for converting the abundant and low-cost biomass waste into high-valued porous carbons by the green self-activation method for high-energy-density supercapacitor.

Iron and nitrogen anchored hierarchical hollow porous carbon microtubes for an electrocatalytic oxygen evolution reaction

The development of active nonprecious-metal and heteroatom-doped materials is critical for the oxygen evolution reaction (OER). Herein, asphaltene-derived carbon-coated Fe- and N-doped hierarchical hollow porous carbon microtubes were prepared through feasible freeze-drying and carbonization/activation strategies. Cotton with a fibrous morphology acted as a soft template and carbon precursor, while asphaltene with easy graphitization properties was utilized to stabilize the structure of microtubes and accelerate the charge conductivity. Meanwhile, Fe- and N-doping changed the electronic structure of carbon and increased the number of active sites. In particular, the optimum sample displayed excellent OER activity with a lower overpotential of 261.4 mV at 10 mA/cm2 and Tafel slope of 94.60 mV/dec under alkaline conditions. Moreover, the catalyst demonstrated excellent long-term durability with a 10% attenuation rate after continuous operation for 50 h by the chronoamperometry method at a constant potential of 1.5 V. This work provides a strategy for the effective resource utilization of biomass and asphaltene to prepare highly efficient OER electrocatalysts.

Rational Design of 1D Porous Carbon Microtubes Supporting Multi‐size Bi2O3 Nanoparticles for Ultra‐long Cycle Life Lithium‐Ion Battery Anodes

AbstractMulti‐size Bi2O3 nanoparticles supported by 1‐dimensional (1D) porous carbon microtubes (ms‐Bi2O3/CMTs) were favorably constructed through surface‐ion release and in‐ situ oxidation strategy. The prominent 1D porous microtube materials with multi‐size nanoparticles structure can furnish more plentiful electrochemical active sites and shorten lithium storage paths for high‐speed redox reactions, which was conducive to ion transport kinetics. The CV tests with various scan rates verified lithium storage mechanism of ms‐Bi2O3/CMTs with diffusion/capacitance control coexistence. The complexes illustrated an ultra‐long cycle life and extraordinary reversible capacity: it still had a specific capacity of 392.6 mAh g−1 after 3000 cycles at 1 A g−1; and it manifested 546.3 mAh g−1 when it returned to 0.05 A g−1 and continued to 100 cycles after experiencing different current densities of 0.05–5 A g−1, which indicated that ms‐Bi2O3/CMTs is a prospective anode for lithium‐ion batteries (LIBs).

Improved Gas-Sensitive Properties by a Heterojunction of Hollow Porous Carbon Microtubes Derived from Sycamore Fibers

Improved Gas-Sensitive Properties by a Heterojunction of Hollow Porous Carbon Microtubes Derived from Sycamore Fibers

Nitrogenization of Biomass-Derived Porous Carbon Microtubes Promotes Capacitive Deionization Performance

Abstract Nitrogenization of porous carbon provides an effective methodology to promote capacitive deionization (CDI) performance. Exploring a new class of nitrogen-doped porous carbons from waste biomass over commercially available activated carbons is of significant interest in CDI. In this contribution, we present the preparation of nitrogen-doped porous carbon microtubes (N-CMTs) by pyrolyzing willow catkins, a naturally abundant biomass with urea as the nitrogen source. Due to the naturally occurring hollow microtube structure and the high nitrogen content, the as-prepared N-CMTs show an enhanced desalination performance compared to undoped samples. A high deionization capacity of 16.78 mg g−1 predicted by Langmuir isotherm and a stable cycling performance over ten cycles are observed. The result advocates the importance and significance of naturally developed architectures and chemistry for practical CDI application.

Porous hard carbon microtubes from renewable cotton as high-performance anode material for lithium-ion batteries

Consumer electronics or electric vehicles/power grids requires lithium-ion batteries (LIBs) with an increasingly outstanding energy-storage performance. However, the present graphite anode still faces significant challenges on relatively low specific capacity and poor rate performance. Herein, porous hard carbon microtubes (HCMs) were prepared by an activation method using natural cotton as a precursor, and their performance as an anode electrode. The electrochemical results of HCMs showed high performance on initial Coulomb efficiency, rate performance and cycle stability. The micro structure of HCMs were characterized, and the mechanism of high-performance generation of HCMs was analyzed. This article may provide an effective method to improve the electrochemical performance of hard carbon, which is also benefit to further understanding the lithium storage mechanism in porous hard carbon materials.

Hierarchical porous carbon microtubes derived from corn silks for supercapacitors electrode materials

In this paper, efforts are made to develop a novel, simple, efficient yet low-cost method to prepare carbon microtubes (CMTs) derived from corn silks through one-step carbonization process. Furthermore, the CMTs are activated by KOH to prepare hierarchical porous carbon microtubes (HPCMTs) as an electrode material for supercapacitor. The HPCMTs not only inherite the hollow tube-like structure from corn silks but also possess micropores, mesopores, macropores. A maximum specific surface area of 1962.4 m 2 g −1 is achieved by HPCMTs-2, which the weight ratio of KOH/CMTs is 2. The electrochemical performance of the HPCMTs-2 are appraised in 6 M KOH solution as electrolyte via three-electrode system. The electrode materials present the maximum specific capacitance of 291.2 F g −1 at 0.1 A g −1 . When the current density increases 200 times to 20 A g −1 , the capacitance retention rate is 69.6%. Beyond that, the practical application properties of HPCMTs-2 electrode materials are evaluated in symmetric devices assembled with 6 M KOH aqueous electrolyte and 1 M MeEt 3 NBF 4 /PC organic electrolyte respectively. The symmetric supercapacitor with aqueous electrolyte provides an energy density of 5.4 Wh kg −1 at a power density of 5000 W kg −1 and a superb capacitance retention of 97.9% after 10,000 cycles at 4 A g −1 . Besides, the symmetric supercapacitor assembled with organic electrolyte delivers an energy density of 16.4 Wh kg −1 at a power density of 6750 W kg −1 and a good cycling life with a capacitance retention of 81.6% over 10,000 cycles at 4 A g −1 . • Prepare hierarchical porous carbon microtubes (HPCMTs) derived from corn silks. • The impact of the amount of KOH on the morphology and specific surface area. • The HPCMTs possess micro-, meso- and macropores, with N self-doping. • Two-electrode devices with aqueous electrolyte and organic electrolyte. • Influence factors of electrochemical performance are analyzed.

Novel porous carbon microtubes and microspheres produced from poly(CL-b-VbC) triarm block copolymer as high performance adsorbent for dye adsorption and separation

Dandelion-like and microtube-containing novel porous carbons were synthetized from brush type poly (ε-caprolactone-b-4-vinyl benzyl chloride) (poly(CL-b-VbC)) triarm block copolymer with KOH (PCLVbK) and ZnCl2 (PCLVbZn) through optimized chemical activation at low temperature. These porous carbons were used for the adsorption and separation of cationic Malachite green (MG) and anionic Congo red (CR) and Methyl orange (MO) dyes. The synthetized porous carbons were characterized by SEM, N2 adsorption-desorption isotherms, FTIR, Raman and XRD. PCLVbK and Zn porous carbons were quite effective in cationic (MG) dye adsorption from aqueous solution thanks to different functional groups, surface areas and pore volumes. The MG adsorption capacities of PCLVbZn and PCLVbK were found to be 1684 mg/g and 869.5 mg/g, and these results are considerably higher than the other adsorbents studied in the literature. Also, it was determined that while PCLVbZn could adsorb both cationic and anionic dyes, PCLVbK could only perform the adsorption of cationic dyes. The kinetic studies conducted with MG showed that both PCLVbK and Zn porous carbons fitted better with the pseudo-second-order model. At the end of the adsorption equilibrium studies, it was observed that PCLVbZn fitted with both the Langmuir and Freundlich adsorption models while PCLVbK fitted better with the Langmuir model. In conclusion, it was observed that PCLVbK could perform high and fast adsorption and separation owing to its oxygen functional groups, while PCLVbZn turned out to be effective in the adsorption of both anionic and cationic dyes thanks to its large surface area (1006 m2/g) and empty microtubes. Based on these results, it can be argued that PCLVbK and Zn porous carbons are promising adsorbents for both high adsorption and effective separation from aqueous solution.

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.

Hierarchical carbon microtubes from willow catkins for Li–S batteries

It is crucial but quite challenging to cycle carbon waste to prepare useful carbon material for energy storage by green process. Herein, hierarchical porous carbon microtubes synthesized by directly heating willow catkins without activation were used for Li–S batteries. The carbon microtubes loaded >75.0% sulfur were used as the Li–S battery cathodes. The cathodes with high areal sulfur content of 2.6 mg/cm2 deliver an initial discharge capacity of ~800 mAh/g at 0.5 C, and stabilized at 624 mAh/g after ~150 cycles at 0.5 C, with a low degradation rate per cycle (0.13% after 150 cycles or 0.07% after 1000 cycles). Our investigation presents that the fly willow catkins air-contaminants could be collected to use for high-density energy storage.

Reactable ionic liquid in situ-induced synthesis of Fe3O4 nanoparticles modified N-doped hollow porous carbon microtubes for boosting multifunctional electrocatalytic activity

Oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are three paramount electrochemical processes for renewable energy conversion technologies consisting of fuel cells, metal-air batteries and water splitting devices. There remains a big challenge to fabricate low-cost and durable electrocatalysts with optimal catalytic performance for ORR, OER and HER. 3D hollow porous carbon based materials with attractive structural properties are usually constructed as promising candidates for electrocatalysis. Herein, we report a reactable ionic liquid (IL) in situ-induced synthesis of Fe3O4 nanoparticles decorated willow catkins derived N-doped 3D hollow porous carbon microtubes multifunctional electrocatalyst (Fe3O4/NCMTs-800(IL)). IL shows a huge advantage of control in synthesizing small size Fe3O4 nanoparticles, achieving uniform nanoparticles on hollow carbon microtubes owing to the interaction between the IL and carbon substrate. The Fe3O4/NCMTs-800(IL) electrocatalyst affords a positive half-wave potential for ORR, small overpotential for the OER and HER, and high stability for water splitting activity. The as-obtained electrocatalyst exhibits efficient and robust electrocatalytic performance can be ascribed to the special 3D porous structure and the synergistic effect of Fe3O4 and doped-N species. The approach indicates the great electrochemical energy applications for biomass and ionic liquids.

N, S co-doped porous carbon microtubes with high charge/discharge rates for sodium-ion batteries

N, S co-doped porous carbon microtubes, synthesized by polymerization and pyrolysis with sulphur, exhibit high charge/discharge rates for sodium-ion batteries.

Graphitic, Porous, and Multiheteroatom Codoped Carbon Microtubes Made from Hair Waste: A Superb and Sustained Anode Substitute for Li-Ion Batteries

Turning household wastes into useful battery anodes is always a rational way to retard the graphite resources exhaustion and prevent deterioration of the living environment. Although great efforts have been devoted, nearly all evolved carbons are intrinsically amorphous and dense, which is adverse to ions diffusions, electrons transfer, and actives utilization for battery usage. Herein, by selecting common hair waste as the example material, we propose a smart catalytic engineering protocol to make graphitic, porous, and multiheteroatom co-doped carbon microtube anodes for sustained Li-ion batteries. The Ni-based nanofilm matrix evenly immobilized on all hair surface plays a key role in the rapid graphitization of hair and the formation of deep pores. Such evolved carbons with unique functionalized properties can well make up for the shortcomings of hair-carbonized products, exhibiting far superior anodic behaviors on reversible capacity/actives utilization efficiency, cyclic stability/endurance (no capac...

Poplar catkin-derived self-templated synthesis of N-doped hierarchical porous carbon microtubes for effective CO2 capture

Poplar catkins are an environmental pollutant because they can trigger sneezing, shortness of breath, skin allergy and even cause forest fire. It is very attractive to discover ways for reducing the threats of poplar catkins to the environment and human health and even to convert poplar catkins into useful materials. Herein we report on a facile and cost-efficient strategy for the synthesis of hierarchical porous carbon microtubes using poplar catkins as the carbon source. The synthesis involves pre-carbonization and subsequent ZnCl2 activation. The resultant materials not only inherit the natural tubular morphology of poplar catkins, but also develop a hierarchical porous structure, with nitrogen from the biomass being self-doped in the resultant carbon skeleton. The hierarchical porosity, especially the microporosity with the pore size from 0.5 to 1 nm, surface structure, tube wall thickness and nitrogen content can be readily controlled by adjusting the activation temperature and the ZnCl2-to-precursor mass ratio. The produced materials exhibit an excellent CO2 capture capacity. The optimal sample activated at 800 °C with a ZnCl2-to-precursor mass ratio of 4:1 shows an extraordinarily high CO2 adsorption capacity of 6.22 and 4.05 mmol g−1 at 273 and 298 K, respectively, at 1 bar of CO2. Furthermore, the material also displays an excellent recyclability and CO2/N2 selectivity. Our approach not only relieves the environmental pollution of poplar catkins but also leads to the production of a high-performance CO2 adsorbent, which is promising for industrial CO2 capture and separation. It therefore demonstrates an example of trash-to-treasure transformation.

Biomorphic composites composed of octahedral Co3O4 nanocrystals and mesoporous carbon microtubes templated from cotton for excellent supercapacitor electrodes

Biomorphic Co3O4 nanocrystal/mesoporous carbon microtube composites have been hydrothermally prepared and subsequent calcinated using cotton as biotemplate and precursor. The as-prepared composites are fabricated by octahedral Co3O4 nanocrystals with high exposed {1 1 1} facets supported on the porous carbon microtubes and exhibit a unique tubular morphology and porous features. The specific capacitance of the present biomorphic materials is 284.2F⋅g−1 at 1 A⋅g−1, which is 4.8-fold larger than that of pristine Co3O4 prepared without cotton template. The excellent pseudocapacitive performance is attributed to the introduction of porous carbon, the high exposed active facets, the high specific surface area and the optimized hierarchical microstructure inherited from the biotemplate.

Facile fabrication of porous carbon microtube with surrounding carbon skeleton for long-life electrochemical capacitive energy storage

In this report, a hierarchical porous carbon microtubes (CMTs) coated by carbon skeleton was prepared simply and the better role of carbon skeleton in increasing the capacity of CMTs was also investigated. SEM, XRD and XPS were used to character the morphology, crystal structure and the functional group of CMTs and CMTs-coated carbon skeleton. Electrochemistry of materials was conducted by CV and constant-current techniques. The results show that the carbon skeleton improves the electric conductivity of materials and thus a better stability of capacity during charge and discharge was obtained (from 81.2 to 97.1% of original specific capacitance after 10000 GCD cycles at 1 A g−1), although the high specific surface area were altered weakly (1159 m2 g−1). Besides, the incorporated nitrogen-containing functional group can increase the gravimetric capacitance of materials from 253 F g−1 to 278 F g−1, with the volumetric capacitance up to 152 F cm−3. The adequate utilization of nature characteristic of biomass and the simple synthesis of stable carbon skeleton offers a good alternative route for advance CMTs.

β‐Ni(OH)2Nanosheet Arrays Grown on Biomass‐Derived Hollow Carbon Microtubes for High‐Performance Asymmetric Supercapacitors

AbstractThe design and fabrication of biomass‐based energy storage devices is becoming a new trend to reduce the depletion of non‐renewable resources. Herein, β‐Ni(OH)2nanosheet arrays grown on willow catkins‐derived hollow carbon microtubes is prepared for the first time through a facile acid treatment and subsequent hydrothermal process. In the β‐Ni(OH)2@acid‐treated carbon microtube [β‐Ni(OH)2@ACMT] composite, β‐Ni(OH)2nanosheet arrays can be controllably grown on both internal and external surfaces of carbon microtubes, realizing effective utilization of the hollow tubular structure. In addition, carbon microtubes are not only employed as an effective support for the dispersion of β‐Ni(OH)2nanosheets, but also served as a long‐range conductive micro‐current collector for electron transfer. Furthermore, the hollow tubular structure accompanied by the capillary effect provides fast channels for ion diffusion. As a consequence of this unique hierarchical structure, the electrode based on the β‐Ni(OH)2@ACMT composite exhibits a high specific capacitance of 1568 F g−1at 1 A g−1, remarkable capacitance retention of 51.0 % even at 20 A g−1, and excellent cycling stability of 84.3 % retention after 3000 cycles. An asymmetric supercapacitor, with β‐Ni(OH)2@ACMT composites as the positive electrode and porous carbon microtubes as the negative electrode, achieves a high energy density of 37.8 W h kg−1at 750 W kg−1, indicating its potential application in energy storage devices.