Pristine Carbon Cloth Research Articles

Enhancing Capacitance of Carbon Cloth Electrodes via Highly Conformal PEDOT Coating Fabricated by the OCVD Method Utilizing SbCl5 Oxidant

AbstractCarbon cloth shows potential for flexible energy storage electrodes but encounters challenges such as low specific capacitance and limited wettability. This study addresses these limitations by fabricating a highly conformal coating of poly(3,4‐ethylenedioxythiophene) (PEDOT) around 3D carbon fibers via the oxidative chemical vapor deposition (oCVD) method, employing antimony pentachloride (SbCl5) as the oxidant. The oCVD stands out as a robust manufacturing technique for fabricating highly conformal conducting polymer films on porous structures, ensuring the preservation of geometric features and the maintenance of active sites for redox reactions. The resulting PEDOT‐coated carbon cloth electrodes exhibit improved pseudocapacitance and specific capacitance compared to their pristine counterparts. Particularly, oCVD PEDOT‐coated carbon cloth fabricated at various deposition temperatures exhibit a substantial 1.5‐ to 2.3‐fold enhancement in specific capacitance compared to pristine carbon cloth. The highest specific capacitance (170.94 F g⁻¹) is attained in the oCVD PEDOT‐coated carbon cloth fabricated at a deposition temperature of 80 °C, representing a 2.3‐fold enhancement over its pristine counterpart. The PEDOT‐coated carbon cloths demonstrate lower charge transfer resistance compared to their pristine counterparts, further confirming their superior electrochemical performance. This investigation highlights oCVD's effectiveness in fabricating highly conformal PEDOT coating on carbon cloth electrodes for electrochemical energy storage devices.

Electrochemical Analysis and Quantification of Anodic Oxidation on Activated Carbon Cloth Electrodes through Cyclic Voltammetry

Capacitive Deionization (CDI) has applications ranging from water purification to biofuels processing. For CDI to be a viable scalable technology, electrode stability is critical. In extended experiments the activated carbon cloth (ACC), used for the electrode, has been previously observed to degrade as a result of surface oxidation reactions. Carbon cloth oxidation can reduce the surface area and alter the pore structure, in turn reducing the adsorption capacity. While the behavior of oxidation is known, a reliable method of quantifying the extent of degradation is lacking. To quantify it, cyclic voltammetry was explored to measure the capacitance of pristine and oxidized carbon cloth samples. A three-electrode electrochemical cell was used to quantify capacitance of activated carbon cloth in 1M NaCl solution. The specific capacitance of carbon cloth that underwent anodic oxidation was lower than cathodic and pristine carbon cloth. Further tests analyzed the change in the severity of the anodic degradation on whether the initial CDI separations were performed on organic or inorganic ions. Scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) was utilized to verify and quantify surface oxidation. Cyclic voltammetry is demonstrated as a simple and reliable method for analyzing and quantifying anodic oxidation on activated carbon cloth electrodes in CDI stacks.

Nickel sulfide nanowire-filled carbon nanotubes as electrocatalysts for efficient hydrogen evolution reaction

Developing a cost-effective, efficient, and eco-friendly electrocatalyst made from non-noble materials for the hydrogen evolution reaction (HER) is challenging. This research paper presents an application of the nickel sulfide (Ni3S2) nanowires-filled multiwalled carbon nanotubes (CNTs) synthesized on carbon cloth (CC) (Ni3S2@CNTs/CC) as an efficient HER electrocatalyst. The performance of Ni3S2@CNTs/CC as a working electrode was examined for its hydrogen evolution ability. In a 1.0 M KOH solution, Ni3S2@CNTs/CC requires cathodic overpotentials of 381 mV and 549 mV to generate current densities of 10 mA/cm2 and 100 mA/cm2, respectively. Electrochemical impedance measurements showed a low charge transfer resistance value of 3.3 Ω for Ni3S2@CNTs/CC.The evaluation of the electrochemically active surface area revealed that Ni3S2@CNTs/CC has more electrochemical active sites and a higher roughness factor than pristine CC. Most importantly, the current density of Ni3S2@CNTs/CC did not significantly degrade after 3000 CV cycles and 12 h of constant HER. These findings suggest that Ni3S2@CNTs/CC is a cost-effective, highly functional, and stable electrode material for HER in a strongly alkaline medium.

Bimetal-organic framework-derived porous CoFe2O4 nanoparticles as biocompatible anode electrocatalysts for improving the power generation of microbial fuel cells

HypothesisThe relatively lower power density of Microbial fuel cells (MFCs), primarily resulting from weak biofilm habitation and sluggish extracellular electron transfer (EET) at the anode interface, limits their practical implementation on a large scale. To address this challenge, porous CoFe2O4 nanoparticles could be used as anode electrocatalysts based on the following considerations: (i) the introduction of CoFe2O4 nanoparticles endows the anode with a rough surface that facilitates biofilm formation; (ii) the positively charged Co and Fe ions improve the interfacial affinity of anodes, enabling rapid immobilization and colonization of negatively bacteria; (iii) the multi-valent metal states of Co and Fe can function as electron shuttles, mediating EET process between biofilm and anode. ExperimentsCoFe2O4 nanoparticles prepared with a bimetal-organic framework (B-MOF) as precursor, were modified to the surface of carbon cloth as the anode of MFCs. FindingsMFCs equipped with CoFe2O4 anode achieved a maximum power density of 1026.68 mW m−2, which was approximately 3.4 times higher than that of the pristine carbon cloth. Additionally, the biofilm density and viability on the anode were enhanced after CoFe2O4 modification. Considering the facile fabrication process and superior electrocatalytic performance, the CoFe2O4 nanoparticles are promising electrocatalysts for high performance and cost-effective MFCs.

Enhanced performance of microbial fuel cells with a bacteria/shape-controllable aligned carbon nanofibers hybrid biofilm

Improving the bacterial loading contents and extracellular electron transfer (EET) efficiency are promising strategies to enhance the overall performance of microbial fuel cells (MFCs). Herein, an aligned carbon nanofiber-bacteria (ACNF-bacteria) hybrid is prepared and used as an efficient anode employing the electrospinning and co-filtration method. The ACNF matrix reveals rich porous structure, large specific surface area, and obviously improved electrocatalytic performance compared to the pristine carbon cloth (CC) anode. Specifically, MFC with the ACNF-bacteria anode achieves a maximum power density of 704 mW m−2, which is 1.7, 2.1 times higher than that of ACNF, CNF and CC anode. Impressively, the coulombic efficiency and chemical oxygen demand (COD) removal rate for ACNF-bacteria anode reach 47.4% and 87.9%, respectively, far exceeding the CC anode (29.3% and 47.6%). Considering all the factors of low cost, facial fabrication, and high-power output, this novel ACNF-bacteria anode provides great potential for high-performance and cost-effective MFCs in a large scale.

In-situ growth of N@MoO2 microflowers on carbon cloth for high-performance anodes in microbial fuel cells

Anode is a crucial component enabling microbial fuel cells (MFCs) to achieve efficient and durable power generation; however, the preparation of high-performance and up-scaling anodes via facile methods remains a practical challenge. In this study, a nitrogen-doped carbon cloth grafted with molybdenum dioxide microspheres (N @ MoO2/CC) was fabricated using a facile two-step method: in situ polymerization and high-temperature carburization. N @ MoO2/CC exhibited excellent bioelectricity harvesting capacity owing to its dual function of promoting bacterial colonization while enriching electroactive bacteria. The synergy of N-doping and MoO2-grafting enabled the development of a biocompatible interface for bacterial adhesion, resulting in a high bacterial loading capacity. Furthermore, N-doping and MoO2-grafting modifications facilitated the enrichment of Geobacter, thereby enhancing the electrocatalytic activity of the electrode. MFC equipped with N @ MoO2/CC achieved a maximum power density of 3.01 ± 0.23 W·m−2, i.e., 1.43 times the power density achieved using a pristine carbon cloth (2.10 ± 0.04 W·m−2). Additionally, the physical and electrochemical characterizations confirmed that the as-prepared N @ MoO2/CC exhibited excellent operational stability. In summary, N @ MoO2/CC could significantly enhance bacterial colonization, enable electroactive bacteria to flourish, and boost charge transfer efficiency at the microbe–electrode interface, thus improving the electricity generation in MFCs.

X-Fe (X = Mn, Co, Cu) Prussian Blue Analogue-Modified Carbon Cloth Electrodes for Capacitive Deionization

Capacitive deionization is proven to be a viable resource-efficient alternative to remove dissolved salts from water. Further improvements in electrode materials are, however, necessary to achieve a higher efficiency of water desalination. In this work, X-Fe (X = Mn, Co, Cu) Prussian blue analogues of homogeneous particle sizes were grown on electrically conducting activated carbon cloth electrodes by a simple and facile synthesis process. As two-dimensional/three-dimensional (2D/3D) nanostructured Prussian blue analogue materials present favorable electrochemical behavior and ion-exchange possibilities, they are promising for application in capacitive deionization. The modified carbon cloth electrodes exhibit higher salt adsorption capacity and better charge efficiency compared to those constructed with pristine carbon cloth. Cobalt hexacyanoferrate-modified electrodes show the most stable performance, reaching a salt adsorption capacity of 14.47 mg g–1 at 1.0 V, accompanied by the lowest energy consumption (0.389 kWh m–3). This simple strategy is expected to offer possibilities for designing and synthesizing advanced electrode materials with superior performances for application in capacitive deionization devices.

A Study on Polythiophene Modified Carbon Cloth as Anode in Microbial Fuel Cell for Lead Removal

In this study, the performance of carbon cloth (CC) modified with iodine (I2) doped polythiophene nanoparticles (PTh-NP) as an anode was investigated in a double chamber microbial fuel cell (MFC) for the purpose of simultaneous power generation and lead (Pb2+) removal using Shewanella putrefaciens as the biocatalyst. The CC with I2 doped PTh-NP displayed good electrochemical characteristics compared to pristine CC and the CC with undoped PTh-NP. A further increase in the electrical conductivity using the modified CC with biofilm was observed, which matured after 51 h, as evident from cyclic voltametry. The removal of lead for concentrations, viz., 20 ppm, 30 ppm, and 40 ppm, was analyzed. The optimum concentration was found to be 30 ppm with a maximum power density of 0.84 W/m2 and a current density of 1.45 A/m2 at an optimum resistance of 250 ohms. At the end of the process, total organic carbon (TOC) and Pb2+ removal of 95.1% and 89.6%, respectively, were obtained at the optimum concentration. Hence, this study demonstrates the possibility of utilizing MFC for treating low concentrated metal wastewater.

Platinum nanoparticles embedded into polyaniline on carbon cloth: improvement of oxygen reduction at cathode of microbial fuel cell used for conversion of medicinal plant wastes into bio-energy

ABSTRACT A microbial fuel cell is a biological electrochemical system that extracts electrons stored in organic matter by oxidation using catalytic properties of microorganisms at bioanode. The major problem in such device, is however limited power production due to slow kinetic of oxygen reduction at cathode. It is worthwhile to develop new materials that fulfil these requirements. The polymerization of aniline onto carbon cloth for effective electrodeposition of platinum nanoparticles has been carried out by chronoamperometry and cyclic voltammetry. Three materials were thus elaborated, namely pristine carbon cloth, carbon cloth modified with platinum and carbon cloth modified by polymerization of aniline for immobilization of Pt-nanoparticles. The FTIR spectroscopy analysis revealed characteristic band located in 1720–1650 cm−1, attributed to imine function, main component in skeleton of polymer PANI chain. The modified materials have been utilized as cathode in cell inoculated with medicinal plant wastes for improvement of oxygen reduction. Modified cathode with CC-PANI-Pt proved higher performances in all respects: increase of cell voltage from 338 to 765 mV and power density from 862 to 1510 mW/m2 and abatement of COD of microbial inoculum leachate to 88%. Another feature of cell with modified cathode CC-PANI-Pt, was the enormous electric charge density harvested upon oxidation of 1 mL of acetate 7.62 C/cm2 compared to that of cell with pristine CC cathode 0.54 C/cm2. Nevertheless, coulombic efficiency for conversion of medicinal plant wastes into bioenergy was relatively lower 9%, making in evidence that elaborated electrochemical device was rather efficient and benificial environmentally than energetically.

Optimal cobalt oxide (Co3O4): Graphene (GR) ratio in Co3O4/GR as air cathode catalyst for air-breathing hybrid electrolyte lithium-air battery

This study assembles lithium-air batteries with aqueous/aprotic hybrid electrolytes designed for ambient air-breathing in a high relative humidity environment. Cobalt oxide/graphene (Co3O4/GR) nanocomposites are synthesized for improved oxygen reduction and oxygen evolution reaction functionalities. The Co3O4/GR composites with Co3O4 loads of 33.7 wt%, 48.2 wt%, and 62.5 wt% are prepared using hydrothermal synthesis. The Co3O4/GR composites’ catalytic activities on oxygen reduction reaction and oxygen evolution reaction is shown to reduce the polarization of pristine carbon cloth electrode by 40% and serve as a good cathode catalyst. Lithium/air batteries are assembled with a lithium metal/organic electrolyte/ceramic lithium-ion conductive membrane/aqueous electrolyte/air cathode configuration. These batteries with the developed catalysts demonstrate good long-term stability over 120 h when fed with high (70–100%) relative humidity ambient air. More importantly, the results indicate the Co3O4/GR composite in 48.2:51.8 (w/w) is the optimal load for the hybrid electrolyte lithium-air battery due to its balanced amount of catalytic Co3O4 and charge-transfer mediated graphene, and good dispersibility of the nanocatalyst on the planar graphene surface.

Achieving a superior electrocatalytic activity of carbon cloth via atomic layer deposition as a flexible counter electrode for efficient dye-sensitized solar cells

Dye-sensitized solar cell (DSSC) is appealing to renewable energy communities because of its attractive features of low cost, facile assembly and short energy payback time. Nevertheless, the commonly used platinum as the counter electrode (CE) encounters great difficulties in its scarcity and noble nature. Herein, we demonstrate a promising and facile route to attain an earth-abundant, high-conductivity Pt-free flexible CE with the controllable catalytic activity via the atomic layer deposition (ALD) of ZnO as the nanoscale sacrificial template. Our result reveals the electrocatalytic activity of carbon cloth as a function of surface morphology can be successfully tailored by the ALD cycle. It can be ascribed to the interplay of ZnO and carbon during carbothermic reduction, offering the synergetic effects of the defects and oxygen doping on the carbon cloth surface as the enhanced catalytic sites for the regeneration of triiodide into iodide. As a proof of concept, the DSSC using the activated carbon cloth via ALD is enabled to deliver a boosted conversion efficiency by 79%, as compared with that using pristine carbon cloth. Such a promising route can open up a perspective for reaching an earth-abundant, high-conductivity carbon-based flexible CE with the superior catalytic activity for the photoelectrochemical cells.

Surface carboxyl groups enhance the capacities of carbonaceous oxygen electrodes for aprotic lithium−oxygen batteries: A direct observation on binder-free electrodes

In order to achieve the high capacities of carbonaceous oxygen diffusion electrodes for aprotic lithium–oxygen batteries (Li–O2 batteries), most efforts currently focus on the design of rational porous architectures. Only few works study the surface chemistry effect that might be a critical factor influencing the capacities of carbonaceous electrodes. In addition, the surface chemistry effect is very difficult to be studied in composite electrodes due to the influences of binders and additives. Herein, we propose chemically activated carbon cloth (CACC) as an ideal model to investigate the effect of surface functional groups on the discharge capacities of carbonaceous oxygen electrodes for Li–O2 batteries. The intrinsic surface chemistry effect on the performance of carbonaceous cathode is directly observed for the first time without the influences of binders and additives. Results indicate that the surface carboxyl groups introduced by the chemical treatment not only function as the appropriate nucleation sites for Li2O2 but also induce the formation of toroid-like Li2O2. Thus, the surface carboxyl modification enhances the discharge capacities from 0.48 mAh/cm2 of pristine carbon cloth to 1.23 mAh/cm2 of CACC. This work presents an effective way to further optimize the carbonaceous oxygen electrodes via surface functional group engineering

Surface functionalization of carbon cloth with cobalt-porphyrin-based metal organic framework for enhanced electrochemical sensing

Here, a novel synthetic strategy for functionalizing the surface of carbon cloth is demonstrated by introducing a cobalt-porphyrin-based metal organic framework (MOF), Al-TCPP-Co, onto the substrate. The deposition of the rationally designed Al-TCPP-Co layer was achieved in situ by a two-step method – evaporation/transformation procedure. The structural features of the obtained MOF/carbon composite were fully characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), small/wide angle X-ray scattering (SAXS/WAXS), FT-IR spectroscopy, and N2 adsorption. Compared to the pristine carbon cloth, Al-TCPP-Co functionalized carbon composite exhibited a substantially enhanced sensitivity and selectivity in the electrochemical detection of hydrogen peroxide. The great sensing performance based on the Al-TCPP-Co treated carbon electrode renders the method of coating metalloporphyrin-based MOF layers a promising technique to improve the surface properties of carbon materials.

Plasmon Ag-Promoted Solar-Thermal Conversion on Floating Carbon Cloth for Seawater Desalination and Sewage Disposal.

Using solar energy to achieve seawater desalination and sewage disposal has received tremendous attention for its potential possibility to produce clean freshwater. However, the low solar-thermal conversion efficiency for solar absorber materials obstacles their practical applications. Herein, Ag nanoparticles modified floating carbon cloth (ANCC) are first synthesized via wet impregnation, photoreduction, and low-temperature drying strategy, which could float on the water and absorb the solar energy efficiently. It is worth noting that vaporization rate of ANCC with a high wide-spectrum absorption (92.39%) for the entire range of optical spectrum (200-2500 nm) is up to 1.36 kg h-1 m-2 under AM 1.5, which corresponds to solar-thermal conversion efficiency of ∼92.82% with superior seawater desalination and sewage disposal performance. Plasmon Ag promotes the conversion efficiency obviously compared to the pristine carbon cloth because the surface plasmon resonance effect could increase the local temperature greatly. After the desalination, the ion concentrations (Mg2+, K+, Ca2+, and Na+ ions) in water are far below the limit of drinking water. Such high-performance floating ANCC material may offer a feasible and paradigm strategy to manage the global water contamination and freshwater shortage problem.

Mn3O4 Nanoparticle‐Decorated Carbon Cloths with Superior Catalytic Activity for the VII/VIII Redox Reaction in Vanadium Redox Flow Batteries

AbstractMn3O4 nanoparticle‐decorated carbon cloths are prepared as the electrodes for vanadium redox flow batteries. The Mn3O4 nanoparticles are prepared using a two‐step process, in which MnOOH nanoflakes are electrodeposited on the surface of the carbon cloth and subsequently converted to Mn3O4 nanoparticles by a thermal treatment. The prepared electrode exhibits a superior electrocatalytic activity toward the VII/VIII redox reaction. It is demonstrated that the peak potential separation of the VII/VIII redox reaction on the as‐prepared electrode is reduced from 402.0 mV to 82.4 mV at a scan rate of 5 mV s−1 when the pristine carbon cloth is deposited with Mn3O4 nanoparticles. The flow battery with carbon cloths decorated with 0.31 mg cm−2 of Mn3O4 nanoparticles as the electrode exhibits an energy efficiency of 88 %, which is 17 % higher than that of the battery assembled with the pristine carbon cloth at a current density of 100 mA cm−2. Therefore, the superior electrocatalytic activity of Mn3O4 nanoparticles reported offers a promising approach to improve the performance of carbon‐based electrodes, which can reduce the capital cost of vanadium redox flow batteries.

Defect-rich carbon fiber electrocatalysts with porous graphene skin for flexible solid-state zinc–air batteries

Rechargeable flexible Zn–air batteries have attracted great attentions as promising next-generation energy storage devices for portable and wearable electronics. Bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) electrocatalysts on the air electrode are critical for improving the energy storage performance of Zn–air batteries. Free-standing electrocatalysts with superb OER/ORR reactivity render promising flexible power sources for the wearable and stretchable devices. In this contribution, a metal-free electrocatalyst based on surface modification of flexible carbon cloth is proposed. A coaxial cable-like structure with carbon fiber skeleton coated by nanostructured porous and defect-rich graphene skin is in situ fabricated through a facile H2 etching approach. With abundant heteroatoms and defects as active sites, the nanocarbon shells coated carbon cloth exhibits excellent OER/ORR bifunctional activity. The OER and ORR current densities on graphene skin modified carbon fiber are 20 and 3 times higher than those of pristine carbon cloth, respectively. This emerging carbon cloth derived electrocatalyst with porous graphene skin also serves as the air electrode in a rechargeable flexible solid-state Zn air battery with polymer gel electrolyte, and demonstrates stable charge/discharge cycling even under bending. This strategy of constructing nanostructures directly on carbon fibers benefits the rational design of flexible and functionalized materials for electrocatalytic energy applications.

Microwave Reaction: A Facile Economic and Green Method to Synthesize Oxygen‐Decorated Graphene from Carbon Cloth for Oxygen Electrocatalysis

AbstractOxygen‐functionalized graphene is active for oxygen evolution reaction (OER). However, the high costs, complex instruments and pollution risks in the synthesis process make oxygen‐functionalized graphene difficult to be industrialized. The microwave reaction has originally been used to remove the oxygen groups on graphene structures. In this work, the microwave reaction is reversed to decorate oxygen groups on graphene from carbon cloth, by solely using a household microwave oven. After microwave treatment, the carbon cloth shows greatly improved OER performance with a much lower overpotential of 417 mV, in comparison with the pristine carbon cloth (627 mV), due to the decoration of oxygen groups on graphene, a higher electron conductivity and a higher specific surface area. Meanwhile, an overpotential of 542 mV at 10 mA cm−2 is obtained in an acidic electrolyte, which is one of the best values for non‐precious OER catalysts in acidic media. This work provides a facile, green and economic method for producing functionalized carbon catalysts for OER.

Optimal loading of quaternized chitosan nanofillers in functionalized polyvinyl alcohol polymer membrane for effective hydroxide ion conduction and suppressed alcohol transport

A polymer composite was prepared by incorporating 5-20 wt% quaternized chitosan (Q-chitosan) nanoparticles into quaternized polyvinyl alcohol (Q-PVA) to enhance the dimensional stability and conductive properties. Compared with the pristine Q-PVA membrane, the ionic conductivity of the Q-PVA composites with 5–10 wt% Q-chitosan was improved due to increased polymeric free volume hole density. The methanol permeability is suppressed in these Q-PVA/Q-chitosan composites because of the confined swelling in the presence of the fillers, shrinking the free volume size. The Q-PVA/5%Q-chitosan composite exhibits higher peak power density (Pmax) than other Q-PVA membranes in direct methanol fuel cells. A Pmax of 92 mW cm−2 is attained using the Q-PVA/5%Q-chitosan composite at 90 °C with 5–6 mg cm−2 catalyst loads on micro-porous layer-containing carbon cloth. The high load of 20 wt% Q-chitosan does not benefit ionic conduction and power generation, probably due to interfacial resistance at rough surfaces. Using the Q-PVA/5%Q-chitosan composite and reduced catalyst loads of 1–2 mg cm−2 on pristine carbon cloth, Pmax of 90 mW cm−2 can be achieved at 60 °C for both methanol and ethanol fuel cells, but declined at 90 °C due to insufficient catalysts. Overall the Q-PVA/Q-chitosan composite offers a potential electrolyte for energy devices operating in an alkaline environment.

A novel method to significantly boost the electrocatalytic activity of carbon cloth for oxygen evolution reaction

To realize energy-efficient and cost-effective production of hydrogen by electrochemical water splitting, central to the research endeavors is the exploration of highly active and earth-abundant electrocatalysts for oxygen evolution reaction (OER). Promising non-noble candidates for OER are often based on transition metal oxides, while carbon-based electrocatalysts typically receive little attention due to their relatively poor performance. In this work, we present a novel method to significantly activate carbon cloth for OER by creating oxygen-containing functional groups on its surface with the assistance of peroxovanadium complexes, which have been seldom used to oxidize carbon materials. Compared to pristine carbon cloth (P-CC), the activated carbon cloth (A-CC) exhibits higher specific surface area and faster electron transfer rate. Particularly, the overpotential of A-CC (310 mV) to afford a current density of 10 mA cm−2 is much lower than that of P-CC and even comparable to that of noble RuO2/C (280 mV), ranking A-CC among the best reported nonmetal catalysts for OER. Moreover, densely distributed VO2 (B) nanoplates in the intermediate product of VO2 (B)/CC can prevent the highly active A-CC from degrading in air for two months, which endows another excellent feature for this fabrication method.

2D Metal-Organic Frameworks Derived Nanocarbon Arrays for Substrate Enhancement in Flexible Supercapacitors.

Direct assembling of active materials on carbon cloth (CC) is a promising way to achieve flexible electrodes for energy storage. However, the overall surface area and electrical conductivity of such electrodes are usually limited. Herein, 2D metal-organic framework derived nanocarbon nanowall (MOFC) arrays are successfully developed on carbon cloth by a facile solution + carbonization process. Upon growth of the MOFC arrays, the sites for growth of the active materials are greatly increased, and the equivalent series resistance is decreased, which contribute to the enhancement of the bare CC substrate. After decorating ultrathin flakes of MnO2 and Bi2 O3 on the flexible CC/MOFC substrate, the hierarchical electrode materials show an abrupt improvement of areal capacitances by around 50% and 100%, respectively, compared to those of the active materials on pristine carbon cloth. A flexible supercapacitor can be further assembled using two hierarchical electrodes, which demonstrates an energy density of 124.8 µWh cm-2 at the power density of 2.55 mW cm-2 .