Hierarchical Carbon Nanostructures Research Articles

Pinecone derived hierarchical carbon nanostructure as a transducer in a solid-state ion-selective electrode for in vivo analysis of calcium ion

Monitoring extracellular calcium ion (Ca2+) chemical signals in neurons is crucial for tracking physiological and pathological changes associated with brain diseases in live animals. Potentiometry based solid-state ion-selective electrodes (ISEs) with the assist of functional carbon nanomaterials as ideal solid-contact layer could realize the potential response for in vitro and in vivo analysis. Herein, we employ a kind of biomass derived porous carbon as a transducing layer to prompt efficient ion to electron transduction while stabilizes the potential drift. The eco-friendly porous carbon after activation (APB) displays a high specific area with inherit macropores, micropores, and large specific capacitance. When employed as transducer in ISEs, a stable potential response, minimized potential drift can be obtained. Benefiting from these excellent properties, a solid-state Ca2+ selective carbon fiber electrodes (CFEs) with a sandwich structure is constructed and employed for real time sensing of Ca2+ under electrical stimulation. This study presents a new approach to develop sustainable and versatile transducers in solid-state ISEs, a crucial way for in vivo sensing.

Synergising hard-carbon and soft-carbon interactions for delivering metal-free microscale supercapacitors with high specific energy and rapid power delivery

Overcoming the limitations of low energy density and efficiency is a pertinent challenge for the continued development of micro-supercapacitive (MSC) energy storage devices. Traditional metal-thin film-based current collectors suffer from improper interfacial contact with the active material leading to rapid decay in cyclability, while carbon based current collectors underperform in energy density and energy efficiency. In this submission, we design multiscale hierarchical carbon nanostructures and achieve synergistic interactions between them that overcome these limitations. Specifically, the highly conductive (0.2 S/cm) laser-induced-carbon (LIC) acts as an effective current collector with negligible iR drop and simultaneously establishes robust interface with multidimensional nanostructured carbons made-up of (a) porous nanostructured hardcarbon florets (NCF) with high surface area (948 m2/g), open-ended framework and graded porosity and (b) conventional soft-nanocarbons such as one-dimensional single wall carbon nanotubes (CNT) and two-dimensional-graphene (Gr). Consequently, the binder-free MSC resulting from the combination of LIC, NCF and CNT exhibits outstanding high specific capacitance (18 mF/cm2), energy density (10 μWh/cm2), and relaxation time constant (67 ms) without sacrificing power density (1.66 mW/cm2). This is clearly reflected in the unique solitary position achieved by the MSC in the Ragone plot. Fundamentally, the addition of CNT and its integration with non-graphitizable, hard-carbon NCF mimics a ball-net structure that facilitates the ion-migration pathways and thereby delivers the combination of highest energy density and scan rate capability (12,000 mV/s) among all MSCs reported.

Electrostatic Interaction‐directed Construction of Hierarchical Nanostructured Carbon Composite with Dual Electrical Conductive Networks for Zinc‐ion Hybrid Capacitors with Ultrastability

Metal–organic framework (MOF)‐derived carbon composites have been considered as the promising materials for energy storage. However, the construction of MOF‐based composites with highly controllable mode via the liquid–liquid synthesis method has a great challenge because of the simultaneous heterogeneous nucleation on substrates and the self‐nucleation of individual MOF nanocrystals in the liquid phase. Herein, we report a bidirectional electrostatic generated self‐assembly strategy to achieve the precisely controlled coatings of single‐layer nanoscale MOFs on a range of substrates, including carbon nanotubes (CNTs), graphene oxide (GO), MXene, layered double hydroxides (LDHs), MOFs, and SiO2. The obtained MOF‐based nanostructured carbon composite exhibits the hierarchical porosity (Vmeso/Vmicro: 2.4), ultrahigh N content of 12.4 at.% and “dual electrical conductive networks.” The assembled aqueous zinc‐ion hybrid capacitor (ZIC) with the prepared nanocarbon composite as a cathode shows a high specific capacitance of 236 F g−1 at 0.5 A g−1, great rate performance of 98 F g−1 at 100 A g−1, and especially, an ultralong cycling stability up to 230 000 cycles with the capacitance retention of 90.1%. This work develops a repeatable and general method for the controlled construction of MOF coatings on various functional substrates and further fabricates carbon composites for ZICs with ultrastability.

Octopus-like carbon nanomaterial for double high stretchable conductor

One dimensional conductive nanowire is an ideal component for efficient percolation network, which is used to construct highly conductive stretchable elastomer in wearable electronics. The percolation network frequently meets with the trade-off between high conductivity and high stretchability (“double high”) due to the interfacial stress concentration between conductive nanowire and elastomer matrix. Inspired by the octopus' structure, a hierarchical carbon nanostructure of carbon nanotubes riveted on carbon sphere (CNTs-CS) is proposed to synthetically couple high conductivity with high stretchability. As the ''octopus body'', carbon sphere anchor into elastomer matrix to allow the uniform distribution of stretching stress. As the ''octopus feet'', highly conductive carbon nanotubes remain robust linkage state under stretching strain, which ensures the generation of highly efficient percolation network. The stretchable conductor (CNTs-CS in Dragonskin) exhibits good conductivity (1.7 × 10 4 S m −1 ), stretchability (>550%) and mechanical stability (>5000 cycles). The stretchable conductor is successfully assembled in many stretchable electronic devices, including a LED-based illuminating system without obvious brightness changes under various deformations, and strain sensor exhibiting excellent sensing performance in the detection of human physical signs. This unique design strategy reveals a great application prospect in the wearable electronics.

Achieving fast Zn-ion storage kinetics by confining nitrogen-enriched carbon nanofragments in a honeycomb-like matrix

Contriving ingenious and stable carbon structures is critical but of great challenge to improve the electrochemical kinetics in Zn-ion storage devices. In this study, nitrogen-enriched carbon nanofragments confined in a three-dimensional honeycomb-like hierarchical porous matrix are designed and constructed with a simple in situ confined thermal polymerization and carbonization strategy. By employing the as-prepared hierarchical carbon nanostructures for an advanced Zn-ion hybrid supercapacitor, a record high-rate capability has been obtained, manifested as a high specific capacity of 101.3 mAh g−1 at an extraordinary fast discharge rate of 100 A g−1. Additionally, a maximum energy density of 130.2 Wh kg−1 at a power density of 185 W kg−1, and a peerless power density of 92500 W kg−1 at the corresponding energy density of 93.7 Wh kg−1 are achieved, demonstrating the feasibility for high-power Zn-ion storage devices. Further kinetics and mechanism studies reveal that the fast Zn2+ storage kinetics originates from the N-enriched chemistry and the multiscale pore network which provide a hydrophilic surface, boost charge transfer, and expedite the ion diffusion.

A biomass-based hierarchical carbon via MOFs-assisted synthesis for high-rate lithium-ion storage

A hierarchical nanostructured biomass-based carbon material derived from banana peels slurry and ZIF-8 hybrids (HNBZC) is introduced with excellent lithium-ion storage and rate capability. HNBZC was prepared through a hollow MOFs-assisted hard template strategy, in which we can easily control the pore size and doping element content to further improve the electrochemical performance of biomass-based carbon. HNBZC can reversibly deliver a capacity of 620 mAh g−1 at current densities of 20 mA g−1, and 61 mAh g−1 is still obtained at a high current density of 50 A g−1. Furthermore, a capacity retention ratio of 80% is achieved after 780 cycles at 5 A g−1. Our results indicate a promising method to obtain a carbon material with enhanced electrochemical performance based on natural biomass waste.

In situ self-boosting catalytic synthesizing free-standing N, S rich transition metal sulfide/hierarchical CNF-CNT architectures enable high-performance lithium-sulfur batteries

Advanced hierarchical carbon-based hybrid (CH) nanostructures, typical carbon nanotubes/carbon nanofibers hybrid (CNT-CNF), with rationally tailored components, structures, and chemistries, have been widely dedicated to potential energy storage and conversion applications. Here we report a facile methodology for the synthesis of precise hierarchical heteroatom-doped carbon hybrid/transition metal sulfide (CNF-CNT/TMS) nanostructure assemblies with novel in-situ formed TMSs as the catalysts for secondary CNTs growth via a self-boosting catalytic pyrolysis. The key to in situ growth of CNT arrays is obtaining small high active TMS nanocatalysts and sufficient supply of carbon sources originated from polystyrene. Such special structure provides abundant active sites, beneficial for the application of N, S codoped CNF-CNT/TMS hybrid film in the electrochemistry without introducing extra dopants. As a proof-of-concept application, the representative CNF-CNT/Co9S8 hybrid was exploited as a conductive and catalytic membrane reactor in a lithium–sulfur (Li-S) battery. This unique architecture can achieve a maximized synergistic effect of electron/ion transport, polysulfide entrapment and catalytic conversion, which enables significant enhancement in electrochemical performance of Li-S batteries. As anticipated, the Li-S battery exhibits ultrastable long-life (over 1000 cycles, with an ultralow decay of 0.034% per cycle) and high-rate performance (6 C). Moreover, at high loading of sulfur of 3.7 mg cm−2, stable cycling performance with high capacity retention can still be achieved after long-term tests. This work also presents a facile and effective strategy in the development of complex hierarchical carbon nanostructure, which may be a competitive candidate in other energy storage and conversion system.

A Fullerene-Platinum Complex for Direct Functional Patterning of Single Metal Atom-Embedded Carbon Nanostructures.

The development of patterning materials ("resists") at the nanoscale involves two distinct trends: one is toward high sensitivity and resolution for miniaturization, the other aims at functionalization of the resists to realize bottom-up construction of distinct nanoarchitectures. Patterning of carbon nanostructures, a seemingly ideal application for organic functional resists, has been highly reliant on complicated pattern transfer processes because of a lack of patternable precursors. Herein, we present a fullerene-metal coordination complex as a fabrication material for direct functional patterning of sub-10 nm metal-containing carbon structures. The attachment of one platinum atom per fullerene molecule not only leads to significant improvement of sensitivity and resolution but also enables stable atomic dispersion of the platinum ions within the carbon matrix, which may gain fundamentally new interest in functional patterning of hierarchical carbon nanostructures.

Plasma and Thermal Processing for Designing Hybrid Carbon-Nickel Sulfide Composite Electrodes

There are enormous efforts being made to develop alternative energy storage devices and to meet the energy needs beyond consumer electronics and electric vehicles. Considering batteries and supercapacitors as one of the best performing energy storage devices with high specific energy and power density, there are lots of efforts have been applied to improve the electrochemical features. Amide the different approaches, one of the direct method to improve the performance of such devices are by employing potential electrode materials. Transition metal sulfides are considered as the potential candidates for the next-generation energy storage electrodes. The conversion-reaction induced charge storage mechanism makes them as a promising material for designing high-capacity electrodes for electrochemical energy storage devices. However, poor conductivity and pulverization during the cycling process limits their applications as energy storage devices by limiting the cycle life, capacity and energy density. Thus a combination of metal sulfide phases with hierarchical carbon nanostructures is proposed to address these limitations. Additionally, the direct growth of electrode material on the current collector can overcome the issues related to the binders and internal resistance. In this aspect combining metal sulfides with carbon nanostructures directly grown on current collectors can be used as an advanced electrode material for energy storage applications. Herein, a fast, two-step approach is demonstrated for fabricating a hybrid electrode, consisting of trinickel disulfide (Ni3S2), metallic Ni nanoparticle and vertically aligned multi-walled carbon nanotubes (VCN) in the form Ni3S2/Ni@VCN. The VCN structure is prepared by plasma-assisted techniques, and the nickel sulfide is anchored by the thermal annealing. These Ni3S2/Ni@VCN composites can be directly used as a binder-free electrode for energy storage devices without any further processing, which makes the procedure as a promising technique for the fast fabrication of electrode materials for energy storage devices.

DABCO Derived Nitrogen-Doped Carbon Nanotubes for Oxygen Reduction Reaction (ORR) and Removal of Hexavalent Chromium from Contaminated Water.

Though chemically-derived reduced graphene oxide (CDG) from graphite oxide (GO) precursors is a widely practiced procedure for the large-scale production of graphene, the quality and quantity of thus obtained CDG is dependent on the reduction strategy used. In this work, we report an all-solid-state, residue-free, microwave process for the reduction of graphene oxide and subsequent growth of carbon nanotube ‘separators’ from a single precursor, namely DABCO (1,4-diazabicyclo[2.2.2]octane). The utility of our newly developed technique in efficiently and effectively reducing graphene oxide and in growing nitrogen-doped carbon nanotubes via catalysts like palladium and iron into unique mesoporous, 3-D hierarchical carbon nanostructures is demonstrated. The applicability of the thus obtained palladium embedded in Pd@NCNT-rGO nanoarchitectures for the oxygen reduction reaction (ORR) is investigated. When carbon fiber (CF) was used as the substrate, three-dimensional Fe@NCNT-CF were obtained, whose capability as versatile adsorbents for hexavalent chromium ion removal from contaminated waters was also demonstrated.

In situ construction of 3-dimensional hierarchical carbon nanostructure; investigation of the synthesis parameters and hydrogen evolution reaction performance

Hierarchical 3-dimensional (3D) carbon nanostructures have potential applicability in several electrochemical energy applications own to their sizeable effective surface, specific energy density, cycling stability and flexibility. Herein, combining electrospinning with in situ chemical vapor deposition (CVD) technologies as an efficient and secure procedure is applied for constructing 3D carbon nanostructure-based on carbon fibers (CFs) and electrospun carbon nanofibers (ECNFs). Affect the catalysis type, immersion solution, carbon sources and treat temperature are experimentally demonstrated. Cactus-like 3D carbon nanomaterials are constructed via growth forest-like carbon nanofibers (CNFs) directly on both CNFs and CFs at 900 °C using Ni as a catalyst, cellulose acetate (CA) as carbon source and ethanol-urea as an immersions solution. The Ni/CNFs/ECNFs mat exhibits a large surface area of 342.3 m2 g−1, while just 19.3 m2 g−1 is recorded to Ni/CNFs/CFs. Based on the nano-nonwoven structure and forest-like grown CNFs nanostructure, Ni/CNFs/ECNFs exhibit a favorable hydrogen evolution reaction (HER) performance in an alkaline medium with a low overpotential of 88 mV to deliver 10 mV cm−2 current density and Tafel slope of 170 mV dec−1. This work proves the synthesis parameters of 3D hierarchical carbon nanostructures and their enticing to apply as an advanced substrate for electrochemical applications.

Single-atom-sized Ni–N4 sites anchored in three-dimensional hierarchical carbon nanostructures for the oxygen reduction reaction

Single-atom-sized Ni–N4 sites embedded in three-dimensional and hierarchically structured carbon exhibit a high catalytic activity for the ORR.

Hierarchical three-dimensional graphene-based carbon material for high-performance lithium ion batteries

Hierarchical three-dimensional graphene-based carbon materials have been successfully prepared via a template-assisted approach. It is found that the structure, morphology, graphitization degree, surface area and pore volume for the obtained carbon materials could be easily controlled by adjusting the amount of reactant and template. The results show that the obtained hierarchical nanostructured carbon material possesses a very stable reversible capacity of 395 mAh g−1 at 1C and exhibits extremely high reversible capacity of 163 mAh g−1 at the high rate of 20C. The large macroporous network and small mesopores in the materials can facilitate electrolyte and lithium ion transportation. The hollow carbon nanoparticles composed of stacked graphene can favor the electron diffusion within the materials. The micropores in the carbon materials can also increase the reversible capacity.

High-performance microwave absorption of hierarchical graphene-based and MWCNT-based full-carbon nanostructures

A creative fabrication strategy is proposed for synthesizing two kinds of hierarchical graphene-based and MWCNT-based full-carbon nanostructures (FCNS), both of which are excellent microwave absorption (MA) fillers. Through using precursor graphite and MWCNTs, the FCNSs are prepared by simple ultrasonic exfoliation/dispersion and exothermal erosion methods. The hierarchical carbon nanostructures (carbon nanoparticles, carbon nanofilms and carbon hollow hemispheres) and abundant interfaces in FCNSs generate strong dielectric loss. Consequently, the FCNSs present ideal microwave impedance match, attenuation characteristics and excellent MA properties. Results show that the MWCNT-based FCNS and graphene-based FCNS composites achieve extremely strong absorption with minimum microwave reflection loss (RL) values of −58 dB with a thickness of 2.6 mm and −54 dB with a thickness of only 1.2 mm, respectively. And the effective absorption bandwidth (RL < −10 dB) can be reached to 3.44 GHz at 1.4 mm and 4.3 GHz at 1.1 mm, respectively. Moreover, we also elaborate on the fundamental MA mechanism and correlation between the nanostructures and MA properties. The ultrathin MAM can be used as predominant candidate with strong MA properties and wide bandwidth.

Hierarchical nanostructured carbons as CO2 adsorbents

Synthesis and characterization of hierarchical carbon materials, CMK-5 type, with high specific surface areas and large pore volumes is reported and tested in CO2 adsorption. These materials were successfully synthesized by the nanocasting process using a hard silica template SBA-15, furfuryl alcohol (FA) as carbon precursor, and 1,3,5-trimethylbenzene (TMB) as solvent. The percentage of FA, and the FA:TMB volume ratio were the synthesis parameters evaluated to determine the accurate amounts to impregnate the pore walls of the template. Both parameters influence the formation of carbon materials with a 2D porous structure and hexagonal tube array. CMK-5 materials achieved specific surface areas up to 2200 m2/g and total pore volumes ca. 2 cm3/g. The characterization techniques allowed us to establish a correlation between the different textural, structural and morphological properties and the carbon dioxide adsorption capacity. The CO2 adsorption capacity at 308 K up to 1 bar has a strong relationship only with the micropore volume, but at higher pressure (up to 10 bar) the CO2 adsorption capacity depends not simply on the amount of micropores but also of the small mesopores present in these carbons, reaching a maximum value of 7 mmol/g, at 308 K and up to 10 bar.

Highly Dispersed Catalytic Co3S4 among a Hierarchical Carbon Nanostructure for High-Rate and Long-Life Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are next-generation energy storage systems with high energy density, and the rate performance is a very important consideration for practical applications. Recent approaches such as introducing catalytic materials to facilitate polysulfide conversion have been explored, yet the results remain unsatisfactory. Here, we present an optimized Li-S electrode featured by a large amount of highly dispersed Co3S4 nanoparticles (∼10 nm in size) throughout a hierarchical carbon nanostructure hybridized from ZIF-67 and carbon nanotube (CNT) sponge. This enables homogeneous distribution and close contact between infiltrated sulfur and Co3S4 nanoparticles within the ZIF-67-derived N-doped carbon nanocubes, leading to effective chemical interaction with polysulfides, maximum catalytic effect and enhanced lithium ion diffusion, while the built-in three-dimensional CNT network ensures high electrical conductivity of the electrode. As a consequence, the Li-S battery exhibits both extraordinary rate performance by maintaining a capacity of ∼850 mAh g-1 at very high charge/discharge rate (5 C) and long-term cycling stability with 85% retention after 1000 cycles at 5 C (an average capacity fading rate of only 0.0137% per cycle).

Hierarchically structured activated carbon for ultracapacitors.

To resolve the pore-associated bottleneck problem observed in the electrode materials used for ultracapacitors, which inhibits the transport of the electrolyte ions, we designed hierarchically structured activated carbon (HAC) by synthesizing a mesoporous silica template/carbon composite and chemically activating it to simultaneously remove the silica template and increase the pore volume. The resulting HAC had a well-designed, unique porous structure, which allowed for large interfaces for efficient electric double-layer formation. Given the unique characteristics of the HAC, we believe that the developed synthesis strategy provides important insights into the design and fabrication of hierarchical carbon nanostructures. The HAC, which had a specific surface area of 1,957 m2 g−1, exhibited an extremely high specific capacitance of 157 F g−1 (95 F cc−1), as well as a high rate capability. This indicated that it had superior energy storage capability and was thus suitable for use in advanced ultracapacitors.

Dual coexisting interconnected graphene nanostructures for high performance supercapacitor applications

A high-quality hierarchical carbon nanostructure consisting of graphene nanosheets and nanoscrolls can be synthesized by a facile and scalable molten salt method. This carbon nanostructure is here proposed as a high-performance supercapacitor electrode material.

Dual Tuning of Biomass-Derived Hierarchical Carbon Nanostructures for Supercapacitors: the Role of Balanced Meso/Microporosity and Graphene.

Rational design of advanced carbon nanomaterials with a balanced mesoporosity to microporosity is highly desirable for achieving high energy/power density for supercapacitors because the mesopore can allow better transport pathways for the solvated ions of larger than 1 nm. Inspired by the inherent meso/macroporous architecture and huge absorption ability to aqueous solution of auricularia biomass, we demonstrate a new biomass-derived synthesis process for the three-dimensional (3D) few-layered graphene nanosheets incorporated hierarchical porous carbon (GHPC) nanohybrids. The as-prepared GHPC nanohybrids possess a balanced mesoporosity to microporosity with much improved conductivity, which is highly desirable for achieving high energy/power density for supercapacitors. As we predicted, they delivered a high specific capacitance of 256 F g−1 at 1 A g−1 with excellent rate capability (120 F g−1 at 50 A g−1) and long cycle life (92% capacity retention after 10000 cycles) for symmetric supercapacitors in 1 M H2SO4. Based on the as-obtained carbon materials, a flexible and all-solid-state supercapacitor was also assembled, which can be fully recharged within 10 s and able to light an LED even under bended state. Such excellent performance is at least comparable to the best reports in the literature for two-electrode configuration under aqueous systems.

Filtration properties of hierarchical carbon nanostructures deposited on carbon fibre fabrics

Hierarchical carbon nanostructures have been produced and examined for their use in liquid filtration experiments. The nanostructures are based on carbon nanotube growth and graphite oxide sponge deposition on the surface of commercially available carbon fibre fabrics. The hierarchical nanomaterial construction on the carbon fibre fabric is made possible due to the chemical vapour deposited carbon nanotubes which act as anchoring sites for the solution deposited sponge nanomaterial. The nanomaterials show a high capacity for Rhodamine B filtration, with the carbon fibre—carbon nanotube—graphite oxide sponge fabric showing filtering performance comparable to a commercial activated carbon filter. After 40 successive filtrations of 10 mg ml−1 Rhodamine B solution, the filtrate of dual modified fabrics returned an increase in transparency of 94% when measured at approx. 550 nm compared to 72% for the commercial carbon filter. When normalised with respect to the areal density of the commercial filter, the increase in optical transparency of the filtrate from the dual modified fabrics reduces to 65%. The Rhodamine B is found to deposit in the carbon nanomaterials via a nucleation, growth and saturation mechanism.