Bamboo-like Structure Research Articles

Carbon nanotube-Yttrium iron garnet nanohybrid synthesized via chemical vapor deposition and its potential application in fabricated screen-printed patch antenna

Carbon nanotube-Yttrium iron garnet (CNT-YIG) nanohybrid has been successfully synthesized using chemical vapor deposition (CVD) with yttrium iron garnet (YIG) nanopowders as catalyst, ethanol as carbon stock, and argon as carrier gas. Carbon nanotube (CNT) was observed to have grown from the YIG nanopowders with bamboo-like structures of CNT at a synthesis temperature of 900 °C. FESEM and RAMAN characterization indicated that the CNT-YIG nanohybrid exhibited the growth of bamboo-like CNT with high graphitization. Further analysis of electrical properties showed that the CNT-YIG nanohybrid has exhibited conductivity due to the CNT growth. The nanohybrid in the form of powders was then mixed with an organic vehicle to produce thick film paste and screen-printed onto a substrate as the working material for patch antenna application. Initial measurements using VNA indicated that CNT-YIG nanohybrid gave significant results regarding return loss and bandwidth, proving that the materials could have great potential to enhance patch antenna performance due to their combined electrical and magnetic properties.

Fe/Cl/N triply-doped bamboo-like structure wrapped with Fe3C nanoparticles for electrochemical selective nitrite detection

Nitrite is commonly found in the natural environment and in everyday human activities. However, excessive nitrite consumption can potentially harm human health. Consequently, it is crucial to develop a reliable and sensitive method for nitrite detection. In this work, trichloroacetic acid functionalized Cl-Fe-MIL-88B metal-organic framework is obtained through nucleophilic reaction between animated Fe-MIL-88B and trichloroacetic acid, which is then annealed with melamine in an N2 atmosphere to produce the Fe/Cl/N triply-doped bamboo-like carbon nanotubes (CNTs) wrapped with Fe3C nanoparticles. Owing to the effective doping of Fe/Cl/N elements, the charge distribution and chemical activity of the bamboo-like structure are tailored, greatly improving the conductivity and facilitating electron transfer of the composite for potential electrocatalytic reaction. The Fe3C nanoparticles wrapped inside the CNTs contribute to expose more active sites and provide effective surface area. Accordingly, the Fe/Cl/N doped bamboo-like structure modified glassy carbon electrode shows excellent electrochemical nitrite sensing properties with a high sensitivity of 1060 µA cm−2 mM−1, a low detection limit of 0.61 µM in a wide linear concentration range of 5–5000 μM, as well as good anti-interference and long-term stability. Also, the electrochemical sensor has a satisfactory recovery rate for detecting nitrite ions in spiked milk samples. This work proposes a simple precursor chlorination and pyrolysis strategy to obtain metal-filled bamboo-like structure with high electrical conductivity and electrocatalytic properties, endowing great potential in food safety and environment monitoring.

Converting Carbon Dioxide into Carbon Nanotubes by Reacting with Ethane.

The urgency to mitigate environmental impacts from anthropogenic CO2 emissions has propelled extensive research efforts on CO2 reduction. The current work reports a novel approach involving transforming CO2 and ethane into carbon nanotubes (CNTs) using earth-abundant metals (Fe, Co, Ni) at 750 °C. This route facilitates long-term carbon storage via generating high-value CNTs and produces valuable syngas with adjustable H2/CO ratios as byproducts. Without CO2, direct pyrolysis of ethane undergoes rapid deactivation. The participation of CO2 not only enhances the durability of the catalyst, but also contributes about 30 % of the CNTs production, presenting a viable solution to CO2 challenges. The CNT morphology depends on the catalyst used. Co- and Ni-based catalysts produce CNT with a 20 nm diameter and micrometer length, whereas Fe-based catalysts yield bamboo-like structures. This work represents a pioneering effort in utilizing CO2 and ethane for CNT production with potential environmental and economic benefits.

In-Situ Flame-Synthesized Carbon Nanomaterials via an Impinging Swirl Flow with an N-Butanol Pool

ABSTRACT This study aims to investigate the impact of flow rotation and oxygen concentration on the synthesis of carbon nanomaterials using n-butanol diffusion flames in a rotating stagnation flow with a liquid pool and a catalytic Ni substrate. With increasing angular velocity (ω), the diffusion flame shifts slightly toward the upper oxidizer nozzle, experiences a lower strain rate, and becomes stronger with a higher maximum flame temperature at a fixed oxygen concentration (ΩO). Meanwhile, the soot layer thickens and gradually turns yellowish. Field Emission Scanning Electron Microscopy (FESEM) analyses confirm that carbon nanotubes (CNTs) can only be fabricated at ω = 2 or 3 rps when ΩO = 21%, highlighting the critical role of flow rotation. Interestingly, the optimal positions for CNT synthesis consistently occur at the same sampling position (1.5 mm below the upper edge of the blue flame) for all values of oxygen concentration (ΩO). The corresponding temperature ranges for ΩO = 19%, 18%, and 17% are approximately 950°C, 820–920°C, and 800–850°C, respectively, which align with existing literature. High-resolution transmission electron microscopy (HRTEM) images reveal both typical straight tubular and bamboo-like CNT structures. Raman spectra indicate superior graphitization at high angular velocities (ω). Notably, at ω = 0 rps, the intensity ratio of the D- and G-bands is greater than 1 (ID/IG >1); however, as ω increases, the opposite holds (ID/IG <1), with its value gradually decreasing. This suggests that the swirl effect enhances graphite layer crystallization. Importantly, the strain rate controlled by flow rotation significantly influences CNT fabrication, considering both residence time and carbon source. The key finding of this study is that swirl flow enhances both the quality and quantity of CNTs synthesized via n-butanol diffusion flames.

Growth paths in polycrystalline thin films

The polycrystalline grain microstructure of metallic thin films coarsens during grain growth in a unique way when the initial grain structure contains multiple grains in the film thickness. A regime with fast coarsening is followed by a regime of slow coarsening. At the same time, the grain structure itself undergoes clear structural changes from a bulk-like to a bamboo-like structure. The overall coarsening process evolves continuously, whereas the growth paths of individual grains do not follow the ones observed and predicted in either two- or three-dimensional grain growth.

Self-assembled bamboo-like carbon nanotubes based on chiral H8BINOL sensors to recognize cinchonidine efficiently by diastereoisomer complexes.

Fluorescence recognition for the antimalarial cinchonidine could be achieved efficiently and rapidly through bamboo-like carbon nanotubes based on chiral conjugated H8BINOL derivatives. Herein, it was proved that the chiral fluorescence probe H8BINOL exhibited excellent fluorescence identification ability for cinchonidine. The structure and size of the S-1 (S-(3,3'-phenyl)-5,5'6,6',7',8,8'-octahydro-[1,1'-dinaphthalene]-2,2'-diol) and R-1 (R-(3,3'-phenyl)-5,5'6,6',7',8,8'-octahydro-[1,1'-dinaphthalene]-2,2'-diol) were studied by using the DLS, TEM, and SEM spectra, which exhibited a self-assembled bamboo-like carbon nanotube structure. In the CD (circular dichroism) test, cinchonidine was added to a pair of enantiomers of H8BINOL derivatives. The different configurations of H8BINOL derivatives showed significantly different Cotton effects for cinchonidine, indicating that cinchonidine formed diastereoisomer π-π complexes with different configurations of H8BINOL derivatives. From the AFM tests, it was revealed that cinchonidine could effectively quench the fluorescent spot of the probes quickly. The fluorescence titration tests demonstrated that 6.4 × 10-7 mol of cinchonidine could completely quench the fluorescence sensor of S-1 (2 × 10-5 M, 2 mL) through the formation of a 1 : 1 complex. The limit of detection (LOD) of S-1 was calculated to be 6.08 × 10-10, which indicates that S-1 has a high sensitivity and can be applied effectively to the practice of identifying cinchonidine. Meanwhile, the fluorescence sensor R-1 also exhibited the same sensibility with a low limit of detection (7.60 × 10-10).

Microstructural evolution and micro-mechanical properties of non-isothermal solidified zone in TLP bonded Ni-based superalloy joints

Transient liquid phase (TLP) bonding is a promising process for the joining and repairing of nickel-base superalloys. One of the most important parameters in TLP bonding is the bonding time required for sufficient isothermal solidification which prevents the formation of undesirable precipitated phases. In the present work, the effect of bonding time on the microstructure, type, and evolution of precipitates in the non-isothermal solidified zone (NSZ) and their effect on micro-mechanical properties were systematically investigated using multi-scale tests in TLP bonded Mar-M247 superalloy joints with Ni-15.2Cr-3.74B interlayer at 1230 ℃. For a bonding time of 5 min, dual-phase M23(C, B)6 - γ/γ’ (where M is a mixture of Hf, Ta, Cr, and Ni) with eutectic configuration was formed in NSZ. With the increase in bonding time, the evolution of NSZ microstructure can be summed up as eutectic M23(C, B)6 - γ/γ’, semi-striping dual-phase M23(C, B)6 - γ/γ’, discontinuously striping M23(C, B)6 - γ/γ’, followed by the disintegration of NSZ. As the NSZ counterpart, the isothermal solidified zone (ISZ) is mainly composed of γ/γ’. Accompanied by the dissolution of M23(C, B)6 in the centerline, the proportion of the ISZ increases greatly until the joints are completely occupied by ISZ. Finally, a bamboo-like structure with domain size of ∼100 μm was formed in the joint centerline, along with γ’ reorganized themselves all into cubic shapes and distributed homogeneously. Mechanical property tests demonstrated that in comparison to samples with longer bonding time, the NSZ of the shortest bonding time (5 min) has the highest strength and a subsequent decrease in strength was observed with prolonging the bonding time and post-bond heat treatment. Furthermore, possible solidification/transformation path, segregation behavior, and formation mechanism of NSZ/ISZ evolution were discussed.

Superflexible porous PCSnf-Fe3O4/CNT-PANI BP/PCSnf-Fe3O4 sandwich composite films with excellent electromagnetic wave absorption performance based on integral assembly by electrospinning

Polycarbosilane nanofiber-ferroferric oxide (PCSnf-Fe3O4) films were assembled on both sides of carbon nanotube-polyaniline buckypaper (CNT-PANI BP) by electrospinning to obtain PCSnf-Fe3O4/CNT-PANI BP/PCSnf-Fe3O4 sandwich porous composites, with a diameter of 110–120 mm and a thickness of 150–200 µm. The Fe3O4 nanoparticles adhered on the PCS nanofibers formed a bamboo-like or plum-like structure. The PANI nanoparticles were uniformly embedded in the CNT network. Both PCSnf-Fe3O4 film skin layers were well bonded to the CNT-PANI BP core layer, with two main forms of the interlayer interface of rattan-like and root-like entanglement. The sandwich composite film (SCF) with 15.1 wt% Fe3O4 in the skin layers had a density of 0.97 g/cm3, a porosity of 61% and a total pore area of 30.1 m2/g, with a multimodal pore size distribution. The SCFs were superflexible, being tightly wound around a 4 mm diameter glass rod and repeated 100 times without damage. The absorption performance of the SCF was significantly improved by introducing Fe3O4 nanoparticles into its skin layers. The SCF with 11.8 wt% Fe3O4 in its skin layers achieved optimal dielectric and magnetic loss matching, with minimum reflection loss of − 43.54 dB and maximum effective absorption bandwidth of 6.97 GHz.

CO2-Rich Gas Conversion to Carbon Nanotube via Molten Salt Electrolysis

The CO2 capture via electrolysis process is a potentially promising and attractive pathway for greenhouse gas removal and global warming reduction by converting CO2 into value-added materials. In this study, the conversion of CO2 from CO2-rich gas into value-added carbon nanomaterial was successfully achieved via molten Li2CO3 electrolysis with a NiCr anode and a stainless steel cathode. The characterization by FESEM and TEM analyses showed that the obtained carbon product was a carbon nanotube with a bamboo-like structure and an outer average diameter of 36 nm. The EDS and XRD characterization indicated the growth of carbon nanotube in electrolysis was achieved through metal nucleation points on the electrolysis cathode. In addition, the Raman analysis showed that the carbon product exhibited high quality and crystallinity. The results from the present study revealed that the molten carbonate electrolysis offered a viable approach for direct transformation of CO2 from industrial flue gas into valuable carbon product, providing an alternative solution to reduce CO2 emissions.

Bamboo-like tubular nitrogen-doped carbon derived from g-C3N4 as an ultra-high performance anode of potassium-ion battery

Carbon materials are still the most widely studied anode materials for potassium ion batteries (PIBs) attributed to their advantages of wide source, controllability, and environmental friendliness. In this paper, a bamboo-like tubular nitrogen-doped carbon material (CNC) was prepared by using g-C3N4 as the precursor and transition metal salt as the catalyst and template. CNC has the advantages of a bamboo-like tubular structure, rich nitrogen content, and large layer spacing. As anode of PIBs, CNC can deliver an impressive initial reversible capacity of 488.6 mAh/g at 0.1 A/g. At a high current density of 1 A/g, CNC still retains a reversible capacity of 291 mAh/g after 1000 cycles. The excellent performance of CNC anode can be due to the porous bamboo-like tubular structure that promotes K ions diffusion and the rich nitrogen content that provides abundant active sites for K ions.

Influence of water content on structural and electrochromic properties of TiO2 nanotube prepared by anodization

TiO2 nanotubes (TNTs) and bamboo-type TNTs structure films were synthesized via anodization from sputtered titanium (Ti) films on indium tin oxide (ITO) glass. Herein, the anodization process was adjusted electrolyte with different amounts of deionized water and ethylene glycol. The optical and structural properties of all films before and after annealing were investigated, which affected electrochromic application. The increasing deionized water content in electrolytes resulted in an increase in the average diameter and a decrease in the average length of TNTs. Furthermore, the bamboo-type TNTs structure was produced at the deionized water volume condition of 3 vol%. The crystallite size of annealed TNTs (a-TNTs) was calculated from the Scherrer equation, which was enhanced when increasing deionized water. TNTs conditions before annealing showed that the amorphous structure and high energy band gap (Eg) exhibited more electrochromic phenomena than the crystal structure. Due to the disordered arrangement of structures, it was easy to insert ions in TNTs. The bamboo-like structure with separate tubes increased the surface area of the reaction, thus exhibiting the best electrochromic properties with ΔT equal to 12.58%.

Bamboo-like N-doped carbon tubes encapsulated Co2P–Fe2P derived from zeolitic imidazolate framework as an efficient trifunctional electrocatalyst for water splitting and Zn-air batteries

The development of high-performance and stable trifunctional electrocatalysts is a pressing challenge for the practical application of water splitting and regenerative Zn-air batteries. Herein, bamboo-like N-doped carbon tubes encapsulated Co2P–Fe2P nanoparticles (CoFe-PN/C) was fabricated via a facile template-sacrificial approach by using CoZn-ZIF trapping Fe3+ (CoFeZn/C) as the precursor. The incorporation of Fe3+ was achieved by the one-pot synthesis approach during crystallization of ZIF, which led to the generation of the unique bamboo-like tube structure under the condition of simultaneous phosphating and carbonization. Benefiting from the large surface area, the optimized electronic structure of active sites and the unique bamboo-like nanotube, the resultant CoFe-PN/C can be used as the trifunctional electrocatalyst possessing a small overpotential at 10 mA cm−2 for the HER (178 mV) and OER (300 mV), as well as a high half-wave potential of 0.884 V for ORR (40 mV more positive than that of commercial 20 wt% Pt/C). Moreover, the self-designed CoFe-PN/C||CoFe-PN/C alkaline electrolyzer driving 50 mA cm−2 only need operating potential of 1.84 V and the maximum discharge power density of the CoFe-PN/C-assembled ZABs could achieve 152.0 mW cm−2, superior to those of Pt/RuO2 couple. This work will facilitate the development and application of trifunctional electrocatalysts based on bi-transition metallic phosphides for energy conversion and storage technology.

Bioinspired anti-freezing 3D-printable conductive hydrogel microfibers for highly-sensitive and wide-range detection of ultralow and high strains

Soft strain sensors that can transduce stretch stimuli into electrical readouts are promising as sustainable wearable electronics. However, most strain sensors cannot achieve highly-sensitive and wide-range detection of ultralow and high strains. Inspired by bamboo structures, anti-freezing microfibers made of conductive poly(vinyl alcohol) hydrogel with poly(3,4-ethylenedioxythiphene)-poly(styrenesulfonate) are developed via continuous microfluidic spinning. The microfibers provide unique bamboo-like structures with enhanced local stress to improve both their length change and resistance change upon stretching for efficient signal conversion. The microfibers allow highly-sensitive (detection limit: 0.05% strain) and wide-range (0%–400% strain) detection of ultralow and high strains, as well as features of good stretchability (485% strain) and anti-freezing property (freezing temperature: −41.1 °C), fast response (200 ms), and good repeatability. The experimental results, together with theoretical foundation analysis and finite element analysis, prove their enhanced length and resistance changes upon stretching for efficient signal conversion. By integrating microfluidic spinning with 3D-printing technique, the textiles of the microfibers can be flexibly constructed. The microfibers and their 3D-printed textiles enable high-performance monitoring of human motions including finger bending and throat vibrating during phonation. This work provides an efficient and general strategy for developing advanced conductive hydrogel microfibers as high-performance wearable strain sensors.

Mechanical Behavior of Bamboo-Like Structures under Transversal Compressive Loading.

Inspired by many biological structures in nature, biomimetic structures demonstrate significantly better mechanical performance than traditional engineering structures. The exceptional mechanical properties of natural materials are attributed to the hierarchical architecture of their structure. Consequently, the implementation of biomimetic structures in the design of lightweight structures with tailored mechanical properties has been constantly increasing in many fields of science and engineering. The bamboo structure is of particular interest because it combines a light weight and excellent mechanical properties, often surpassing those of several engineering materials. The objective of this study was to evaluate the mechanical behavior of bamboo-inspired structures subjected to transversal compressive loading. Structures consisting of bamboo-like thin-walled hexagonal building blocks (unit cells) with different dimensions were fabricated by stereolithography 3D printing and their mechanical performance was evaluated by mechanical testing, high-speed camera video recordings, and finite element simulations. The results of the elastic modulus, yield strength, and strain energy density at fracture were interpreted in terms of characteristic dimensions of the unit cell structure. The failure process was elucidated in the light of images of the fractured structures and simulation strain maps. The results of this study demonstrate that ultralight bamboo-like structures with specific mechanical characteristics can be produced by optimizing the dimensions and number density of the hexagonal unit cell.

Low-density polyethylene-derived carbon nanotubes from express packaging bags waste as electrode material for supercapacitors

A simple and efficient method for disposing of waste low-density polyethylene (LDPE) express packaging bags is proposed in this paper as a way to minimize waste and address the energy shortage at the same time. In addition to following the production of carbon nanotubes (CNTs) derived from LDPE, the application of CNTs as electrodes for supercapacitors was attempted. Waste LDPE bags were pyrolyzed and carbonized with catalyst using a dual-temperature reaction system, a designed 450 °C pyrolysis temperature accompany with different carbonization temperatures (650 °C, 700 °C, 750 °C, 800 °C, 850 °C), and treatment durations (0 h, 2 h, 4 h, 6 h) were investigated. As determined by FE-SEM and FE-TEM, the CNTs synthesized at 750 °C showed a finer tube diameter, much more uniform distribution, bamboo-like structure, as well as the highest yield of 41.9 %, and carbon conversion of 61.2 %. As being charged and discharged 10,000 times, the electrode remained a 93.16 % capacitance and a 92.85 % Coulomb efficiency. A dual-temperature reaction system could be utilized to recycle waste LDPE efficiently, and the LDPE-derived CNTs could be applied for supercapacitors.

Nickel coating on carbon nanotubes and PProDOT-2CH2SH supported Pt nanoparticles as the electrocatalyst for methanol oxidation reaction

The electricity generated by direct methanol fuel cells (DMFCs) comes from methanol oxidation reaction (MOR), which is affected by electrocatalytic activity of anode materials. Herein, Pt nanoparticles supported by the composite of thiol group grafted poly(3,4-propylenedioxythiophene) (PProDOT-2CH2SH) and Ni–N co-doped bamboo-like carbon nanotubes (Ni-NCNT) are prepared and proposed as an anode material for DMFCs. The results from morphological analysis show that the Pt nanoparticles uniformly disperse on the surface of support (PProDOT-2CH2SH/Ni-NCNT) with bamboo-like structure, and there is an electronic effect between the Pt and Ni confirmed by X-ray photoelectron spectroscopy analysis. Electrochemical tests reveal that the PProDOT-2CH2SH/Ni-NCNT/Pt catalyst demonstrates good electrocatalytic activity for the MOR in acidic electrolyte, and the catalyst has higher resistance to CO poisoning than commercial Pt/C. The mass activity (MA) of catalyst is up to 1670.54 mA mgPt−1 with an electrochemical active surface area (ECSA) of 98.0 m2 g−1, and the catalyst maintains good performance after 800 cycles. This work provides a high-performance MOR catalyst in practical application for DMFCs.

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.

The preparation of bifunctional Co-N co-doped carbon with bamboo-like hollow tubular as an efficient electrocatalyst for oxygen reduction and methanol oxidation reaction

• Bamboo-like hollow tubular Co-N-C was prepared by direct pyrolysis method. • The Co-N-C catalyst exhibits a high specific surface area. • The Pt@Co-N-C has a high electrochemical surface area. • The Co-N-C and Pt@Co-N-C exhibit excellent ORR and MOR activity and stability. Catalysts with distinguished properties and stability are very important for the oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) of fuel cells. Herein, we describe a convenient and efficient preparation means to synthesize a bamboo-like hollow tubulous structure Co-N co-doped carbon material (Co-N-C) via a late-model of Co-Imace coordinated compound as the precursor by direct pyrolysis. Additionally, Pt nanoparticles supported by Co-N-C catalysts (Pt@Co-N-C) were prepared using the ethylene glycol reduction procedure. The obtained catalyst exhibited an excellent electro-catalytic property for ORR in alkaline media, which possessed a more positive half-wave potential (0.868V) than commercial Pt/C (0.852V). Moreover, the Co-N-C maintained preeminent long-term stability (91.6 %) after the 21000s and also owned a stronger methanol resistance than Pt/C. The obtained Pt@Co-N-C electrocatalyst exhibited higher MOR activity (96.3 mA cm -2 ), which is 1.6 times greater than that of Pt/C, benefiting from the high electrochemical surface area of Pt@Co-N-C (68 m 2 g -1 ). Furthermore, the Pt@Co-N-C exhibited lower onset potentials, higher I f /I b ratios, and well long-term stability than Pt/C.

Flexible and free-standing electrode for high-performance vanadium redox flow battery: Bamboo-like carbon fiber skeleton from textile fabric

Developing the free-standing and flexible electrodes with high current density and cycle stability is still under debate towards the extensive application of vanadium redox flow batteries (VRFBs). So far, carbon felts, carbon fibers and carbon papers are used which mostly prepared from fossil precursors make them unsustainable. Herein, we first sought to prepare a mechanically flexible and free-standing carbon cloth from terry cloth towel fabric (100% cotton) by using a simple pyrolysis method (TCC). Interestingly, we obtained a bamboo-like carbon fiber structure with a well-balanced micro, -meso, and -macro porosity. Moreover, a low-cost Polyethyleneimine (PEI) is used for Nitrogen doping on carbon cloth skeleton (N-TCC) to improve its electrochemical performance. The as-prepared N-TCC were utilized as efficient electrodes for the VRFBs with higher electrochemical activity towards vanadium species VO2+/VO2+ than TCC and commercial graphite felt (GF) in a 3 electrode electrochemical cell i.e. half-cell. Interestingly, the VRFBs constructed with N-TCCs electrodes (both +ve and –ve half cells) in a full cell configuration at varied current densities from 40 to 160 mA cm−2, we achieved an increased energy efficiency (EE), voltage efficiency (VE), and columbic efficiency (CE) compared to pristine CFs, and TCC based VRFBs. The newly designed cotton based electrodes establishes a unique opportunity for constructing a low-cost, metal-free VRFBs towards a large-scale commercialization of sustainable energy storage system.

Pd single atom stabilized on multiscale porous hollow carbon fibers for phenylacetylene semi-hydrogenation reaction

The extremely high atom dispersion of single atom catalysts (SACs) opens up new opportunities for highly efficient catalysis. However, how to balance the easy accessibility, preparation simplicity, and recoverability for routine nanoscale catalytic supports of SACs is still a big challenge. In this work, the nitrogen doped carbon immobilized Pd SACs with high loading up to 5.6 wt%, in the form of multiscale porous hollow fibers, are prepared through a co-axial emulsion electrospinning and CO2 thermal activating method. The obtained Pd SACs carbon fibers have a bamboo-like tubular structure and multiscale pores on the tube wall, which expose the active sites accessible for reactants. The multiscale porous hollow Pd SACs exhibited both high activity and selectivity for phenylacetylene semi-hydrogenation. This universal method is also applicable for the preparation of many other 1D metal SACs such as Pt, Ru and Co, which exhibits great promising for developing easily available and efficient SACs.