Porous Activated Carbon Research Articles

Synthesis of Ultrathin MnO2 Nanosheets/Bagasse Derived Porous Carbon Composite for Supercapacitor with High Performance

In this paper, activated porous carbon (AC) derived from bagasse was prepared by carbonization and activation using KOH. Then, a hydrothermal route was employed to fabricate ultrathin manganese oxide (MnO2) nanosheets/activated porous carbon (AC) composite (MnO2/AC). AC and MnO2/AC composite were employed as negative and positive electrode materials for a supercapacitor, respectively. An AC electrode delivers excellent electrochemical properties with a specific capacitance of 89 F g−1 at 1 A g−1 and super cycling stability of 89% capacitance retention after 5000 cycles. For a MnO2/AC composite, its specific capacitance can reach 492.5 F g−1 at 1 A g−1, but its cycle performance (78.4% capacitance retention after 5000 cycles) is lower than that of AC (89%). In view of the good electrochemical performance of AC and MnO2/AC composite, a MnO2/AC//AC all-solid-state asymmetric supercapacitor (ASC) was assembled. The constructed ASC exhibits high specific capacitance of 69.375 F g−1 at 1 A g−1 and delivers a high energy density of 24.67 Wh kg−1 at a power density of 814.8 W kg−1. Two ASCs in series can power one LED for more than 70 s. This work demonstrates that MnO2/AC//AC asymmetric supercapacitor shows good practical value.

Facile synthesis of three-dimensional porous carbon for high-performance supercapacitors

Porous activated carbon (PAC) with three-dimensionally (3D) interconnected structure has been successfully synthesized using sucrose and potassium hydroxide as carbon source and pore-forming agent, respectively. On account of its hierarchically porous structure and high specific surface area (1615 m2 g−1), the synthesized porous carbon displays a maximal specific capacitance of 119 F g−1 at 1 A g−1 and a capacitance retention rate of 81.2% after 5000 cycles at 20 A g−1 in 1 M TEABF4/AN electrolyte. It also exhibits a maximal specific capacitance of 178 F g−1 at 0.5 A g−1 and a capacitance retention rate of 88.9% after 10000 cycles at 16 A g−1 in 1 M Na2SO4 electrolyte. Moreover, the fabricated symmetric supercapacitor reveals a high energy density, 16.52 W h Kg−1 in 1 M TEABF4/AN and 15.78 W h Kg−1 in 1 M Na2SO4. Such an excellent supercapacitive performance implies that the prepared activated carbon with 3D interconnected porous structure could be potentially used for high performance energy storage device.

Hybrid material passivation approach to stabilize the silicon nanowires in aqueous electrolyte for high-energy efficient supercapacitor

The rapid oxidation of silicon nanowires (SiNWs) in an aqueous electrolyte imposes boundaries on their real-world applications. To alleviate this drawback, we propose a novel yet simple hybrid material passivation strategy to increase the energy storage capacity and aqueous electrolyte stability of SiNWs for high-energy efficient supercapacitor (SC) applications. Initially, a porous-activated carbon coating was applied to one-dimensional (1-D) metal-assisted chemically-etched (MACE) SiNWs. Later, the redox-active binary nickel cobaltite (NiCo2O4) fine nanoflakes were directly deposited over the carbonized SiNWs via a hydrothermal route. The resultant 1D core–shell architectured hierarchical SiNWs/carbon(C)/NiCo2O4(NCO) (SiNWs/C/NCO) electrode exhibit a peak capacitance of 2166 F/g, with excellent cycling stability over 10,000 charge-discharge cycles in a KOH electrolyte demonstrates its potential practical applications. To prove this claim, the symmetric hybrid SCs was designed. Notably, the symmetric hybrid SCs delivered an excellent energy density of 1.31 mWh/cm3 at a current density of 1 mA/cm2 with an outstanding energy efficiency (∼70–80% over all current densities), which signified a lower energy waste during the discharge process. These results showed that the hybrid material passivation strategy is useful for boosting the energy storage capacity and aqueous electrolyte stability of SiNWs to develop low-cost, high-energy SCs for real-life applications.

Detection of trace Cd2+, Pb2+ and Cu2+ ions via porous activated carbon supported palladium nanoparticles modified electrodes using SWASV

Abstract It is still of great challenge to develop green and efficient electrochemical sensors for detection of trace heavy metal ions. In this work, an efficient method was demonstrated for fabricating Palladium nanoparticles (Pd NPs) uniformly decorated porous activated carbon (PAC). The Pd NPs were in-situ reduced on PAC (Pd@PAC) via a KOH activation and thermal reduction method. The morphology investigation suggests that the Pd@PAC possess typical interconnected micropores and mesopores architecture with Pd NPs evenly dispersed on the surface of PAC. The Pd@PAC modified glassy carbon electrode (Pd@PAC/GCE) was used for the detection of trace Cd2+, Pb2+ and Cu2+ ions by square wave anodic stripping voltammetry (SWASV). It exhibited excellent sensitive and selective detection of heavy metal ions simultaneously and individually, together with good anti-interference, reproducibility, repeatability and stability under the same experimental conditions. Moreover, the Pd@PAC/GCE was utilized to detect heavy metal ions in real sample species, indicating potential application in real environment detection. Porous structure and Pd NPs make Pd@PAC excellent electrochemical activity, its interconnected micropores and mesopores architecture accelerate the mass diffusion and facilitate the deposition-stripping process of heavy metal ions. Pd NPs provide more active sites and improved conductivity significantly. The present investigation provides a green and feasible method to assemble efficient electrochemical sensors and electrocatalytic devices.

Innovative production of highly porous carbon for industrial effluent remediation via microwave vacuum pyrolysis plus sodium-potassium hydroxide mixture activation

This study reports a novel method using microwave vacuum pyrolysis combined with sodium-potassium hydroxide mixture (NaOH-KOH) activation to produce highly porous activated carbon (AC) from palm residue (i.e. palm kernel shell, PKS) – a solid residue constantly produced in large volume by palm industry. The yield and properties of AC produced were found significantly influenced by two key process parameters - type of activating agent and chemical impregnation ratio. The pyrolysis provided fast heating rate (60 °C/min), high temperature (607 °C), and short process time (35 min) to convert PKS into biochar, and the subsequent activation by NaOH-KOH mixture at 1.0 of chemical impregnation ratio resulted in 84 wt% yield of AC. The AC possessed high BET surface area (1320 m2/g) and highly porous structure formed by micro- and meso-pores, thus showing high adsorption capacity. The adsorption capacity of AC was examined via impregnation with nickel and aluminium atoms (termed “Ni/AC” and “Al/AC”) followed by application in treating industrial effluent abundantly released from palm oil mill (termed ‘palm oil mill effluent, POME). Both Ni/AC and Al/AC showed high removal efficiency in reducing the total suspended solid (TSS), oil and grease (O&G), biochemical (BOD) and chemical oxygen demand (COD) in POME. Higher removal efficiency on BOD and COD was observed for Ni/AC and Al/AC than normal AC (non-metallic AC). The production cost of AC using this pyrolysis method was estimated to be ranged from 4 to 10 USD/kg. The results show the exceptional promise of this pyrolysis method as an approach to transform PKS into highly porous AC for utilize as an adsorbent to treat POME.

Toward high-performance all-solid-state supercapacitors using facilely fabricated graphite nanosheet-supported CoMoS4 as electrode material

Hybrids of graphite nanosheet-supported CoMoS4 (GN-CoMoS4) were synthesized through a hydrothermal method. The CoMoS4 nanoparticles are uniformly distributed on the graphite nanosheets, leading to large specific surface area and good electrical conductivity. The GN-CoMoS4 hybrids were systematically studied for electrode materials of supercapacitors. Due to the amorphous characteristic of CoMoS4, which can supply more transportation channels for ion diffusion, together with the large specific surface area and excellent conductivity of GN, the as-prepared hybrid electrode material exhibited a high specific capacitance of 774 F g−1 at the current density of 1 A g−1 and an excellent cyclic stability (94.49% of its initial specific capacitance retained after 6000 cycles at a current density of 8 A g−1). An all-solid-state asymmetric supercapacitor was fabricated using GN-CoMoS4 as positive electrode and porous active carbon (AC) as negative electrode, which exhibited a highest energy density of 42.85 W h kg−1 at 900 W kg−1 and excellent cycling stability (93.2% retention after 8000 cycles). The results demonstrate that the GN-CoMoS4 hybrids are promising candidate for the electrode materials in high-performance supercapacitors because of the well-designed microstructure.

Orthogonal design-guided preparation of multi-level porous-activated carbon by pyrolysis of waste polyester textiles.

Multi-level porous amorphous-activated carbon with excellent adsorption performance was prepared by a ZnCl2-assisted pyrolysis of waste polyester textiles. Experimental parameters were optimized by using orthogonal design. Result of orthogonal design revealed that pyrolysis temperature and pyrolysis time were the dominant individual factors. Samples prepared at the optimal condition were systematically characterized by Brunauer-Emmett-Teller (BET) porosity analyzer, FT-IR spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). Iodine (I2), methylene blue (MB) and phenol (PhOH) were selected as target dyes to measure the adsorption performance. Experimental results showed that porous-activated carbon with multi-level pores could be obtained by optimizing experimental parameters. The specific surface area and total pore volume were calculated to be 846.37m2g-1 and 0.726cm3g-1, respectively. Benefit from its multi-level rich porosity, the optimized sample possessed attractive adsorption performance toward different types of dyes. The corresponding adsorption capacity toward I2, MB, and PhOH were calculated to be 980.48, 384.00, and 300.62mgg-1, respectively.

A porous activated carbon supported Pt catalyst for the oxidative degradation of poly[(naphthaleneformaldehyde)sulfonate

Abstract Wet catalytic oxidation of sodium poly[(naphthaleneformaldehyde)sulfonate], a hazardous contaminant of wastewater streams from the textiles industry, by hydrogen peroxide under ambient conditions was explored over platinum supported on a porous activated carbon (PAC). Bulk and surface properties of the Pt/PAC catalyst were investigated by XRD, XPS, SEM, TEM, FTIR, EPR and thermogravimetric analysis. The parent PAC, derived from pyrolysis and subsequent activation of rice husks, exhibited significant micro- and mesoporosity, and a high degree of surface oxidation. Incorporation of 1.7 wt% Pt resulted in mesopore blockage, and a corresponding drop in surface area, associated with the formation of large ∼8 nm metallic nanoparticles. Poly[(naphthaleneformaldehyde)sulfonate] oxidative degradation was studied as a function of reactant concentration and solution pH, revealing first order decomposition kinetics and good activity over pH 3–9 at ambient temperature. Electron Paramagnetic Resonance (EPR)-DMPO spin trapping experiments confirm that oxidation of the organic pollutant proceeded via hydroxyl radical generation. The 1.7 wt% Pt/PAC catalyst showed excellent catalyst stability for five consecutive runs over 25 h in a fluidised bed reactor, delivering > 85% removal of 100 mg/L sulfonate with negligible Pt leaching or activity loss, and comparable performance for treatment of a real tannery effluent stream with a COD equivalent of 1860 mg/L.

Facile synthesis of mesoporous ZnCo2O4 nanosheet arrays grown on rGO as binder-free electrode for high-performance asymmetric supercapacitor

Asymmetric supercapacitor (ASC) with high energy density has been developed successfully using rGO/ZnCo2O4 composite as positive electrode and activated porous carbon (AC) derived from lotus leaves as negative electrode in KOH solution. Mesoporous ZnCo2O4 nanosheet arrays grown on rGO were prepared via a simple hydrothermal method followed by calcination. RGO/ZnCo2O4 composite exhibited excellent electrochemical performance, which can achieve a specific capacity of 680 F g−1 at current density of 1 A g−1. Due to the high capacitance of porous rGO/ZnCo2O4 nanosheet structure and synergistic effect between the positive and negative electrodes, the RGO/ZnCo2O4//AC ASC showed excellent performance with high specific capacitance of 110 F g−1 at 0.5 A g−1 and good cycling stability with only 2.7% loss of available specific capacitance after 3000 cycles. More importantly, the maximum energy density of this ASC can achieve 31.25 W h kg−1 at a power density of 375 W kg−1. In addition, this ASC can store charge efficiently and two ASCs in series can light up a LED, which can last for over 15 min. These encouraging results show its great potential in the application of energy storage devices.

Single and multi-frequency impedance characterization of symmetric activated carbon single capacitor cells

Electrochemical impedance spectroscopy (EIS) technique is used for characterization of single cell symmetric capacitors having different mass loadings of activated carbon (AC). Relevant values of charge storage capacitance (CT) and internal resistance (ESR) were evaluated by the single frequency and multi-frequency analyses of measured impedance spectra. Curve fittings were based on the non-ideal R-C model that takes into account the parasitic inductance, contributions from electrode materials/contacts and the effects of AC porosity. Higher CT and lower ESR values were obtained not only for the cell with higher mass of AC, but also using the single vs. multi-frequency approach. Lower CT and higher values of ESR that are generally obtained using the multi-frequency method and curve fittings should be related to the not ideal capacitive response of porous AC material and too high frequency chosen in applying the single frequency analysis.

In Situ Generated Dual-Template Method for Fe/N/S Co-Doped Hierarchically Porous Honeycomb Carbon for High-Performance Oxygen Reduction.

Heteroatoms doping is able to produce catalytic sites in carbon materials for oxygen reduction reaction (ORR); while hierarchically porous structure is necessary for efficient exposure and accessibility of the usually limited catalytic sites in such activated carbon catalysts. This work reports an in situ generated dual-template method to synthesize the Fe/N/S co-doped hierarchically porous carbon (FeNS/HPC), with NaCl crystallites formed during the precursor lyophilization process as the primary template to generate ∼500 nm macropores with ultrathin graphene-like carbon-layer walls, and Fe3O4 nanoparticles formed during the high-temperature carbonization process as the secondary template to produce mesopores on the walls of macropores. As well as the coexistence of graphitic-N, pyridinic-N, and thiophene-S which are beneficial to ORR, the as prepared FeNS/HPC possesses a highly graphitized and interconnected hierarchical porous structure, giving a specific surface area as high as 938 m2 g-1. As a consequence, it exhibits excellent four-electron oxygen reduction performance in both alkaline and acid electrolytes. The in situ generation and facile solution removal make the present template method a promising way for scale-up preparation of active porous carbon materials for various applications.

Nitrogen doped hierarchically structured porous carbon fibers with an ultrahigh specific surface area for removal of organic dyes.

Recently, tremendous efforts have been devoted to creating inexpensive porous carbon materials with a high specific surface area (SSA) as adsorbents or catalysts for the efficient removal of organic pollutants. Here, activated porous carbon fibers with hierarchical structures were designed and constructed by an electrospinning technique, in situ polymerization, and activation and carbonization processes. Benefiting from the precursor fiber design and subsequent activation techniques, the activated porous carbon fibers (APCFs) derived from a benzoxazine/polyacrylonitrile (BA-a/PAN) precursor exhibited an ultrahigh SSA of 2337.16 m2 g−1 and a pore volume of 1.24 cm3 g−1, showing excellent adsorption capacity toward methylene blue (MeB, 2020 mg g−1). Interestingly, the APCFs after pre-adsorption of MeB also display robust activation of peroxymonosulfate (PMS) with singlet oxygen for the ultrafast removal of MeB. Meanwhile, the synergistic effect of adsorption and a catalytic oxidation reaction using APCFs can realize outstanding total organic carbon (TOC) removal in a comparatively short time. Moreover, a synergistic adsorption–oxidation mechanism for promoting the removal of MeB using APCFs was proposed. This study is useful for the design and development of novel metal-free carbon adsorbents, catalysts or catalyst carriers with an ultrahigh SSA for various applications.

Chemically Exfoliating Biomass into a Graphene‐like Porous Active Carbon with Rational Pore Structure, Good Conductivity, and Large Surface Area for High‐Performance Supercapacitors

AbstractActive carbons have unique physicochemical properties, but their conductivities and surface to weight ratios are much poorer than graphene. A unique and facile method is innovated to chemically process biomass by “drilling” holes with H2O2 and exfoliating into graphene‐like nanosheets with HAc, followed by carbonization at a high temperature for highly graphitized activated carbon with greatly enhanced porosity, unique pore structure, high conductivity, and large surface area. This graphene‐like carbon exhibits extremely high specific capacitance (340 F g−1 at 0.5 A g−1) and high specific energy density (23.33 to 16.67 W h kg−1) with excellent rate capability and long cycling stability (remains 98% after 10 000 cycles), which is much superior to all reported carbons including graphene. Synthesis mechanism for deriving biomass into porous graphene‐like carbons is discussed in detail. The enhancement mechanism for the porous graphene‐like carbon electrode reveals that rationally designed meso‐ and macropores are very critical in porous electrode performance, which can network micropores for diffusion freeways, high conductivity, and high utilization. This work has universal significance in producing highly porous and conductive carbons from biomass including biowastes for various energy storage/conversion applications.

Porous defect-modified graphitic carbon nitride via a facile one-step approach with significantly enhanced photocatalytic hydrogen evolution under visible light irradiation

Graphitic carbon nitride (g-C3N4) has been considered as one of the most promising photocatalysts for solar energy conversion. However, the intrinsic drawbacks of insufficient visible-light absorption and poor charge separation efficiency seriously limit its practical applications in visible light photocatalytic hydrogen evolution. In this work, a facile one-step strategy was proposed to construct a novel porous defect-modified graphitic carbon nitride (P-DCN) via thermal polymerization of a freeze-dried crystalline mixture containing dicyandiamide (DCDA) and ammonium chloride (NH4Cl) under nitrogen atmosphere, in which both porous feature and two types of defects (cyano group and nitrogen vacancy) were simultaneously introduced into g-C3N4 framework. Results show that the as-synthesized P-DCN Exhibits 26 times higher hydrogen evolution rate (HER) under visible light irradiation than bulk g-C3N4, reaching 20.9 μmol h−1. In combination of porous and defective characteristics, P-DCN even demonstrates 2.0 and 1.8 folds higher HER than highly active porous graphitic carbon nitride (P-CN) and defect-modified g-C3N4 (DCN), respectively. The outstanding photocatalytic performance for hydrogen production originates from the remarkably improved visible light harvesting capability, the notably promoted separation and recombination inhibition of photoinduced charge carriers, and the increased amount of active sites and the strengthened mass transfer resulting from the combination effect of the porous feature, as-formed defects, and the enlarged specific surface area. Moreover, this approach could render a new insight for designing highly efficient visible light photocatalysts for the other transformations including CO2 reduction, environmental remediation, and organic synthesis process.

Micro- and mesoporous-enriched carbon materials prepared from a mixture of petroleum-derived oily sludge and biomass

An innovative way of producing micro-mesoporous enriched active carbon (AC) materials from mixtures of petroleum industrial waste (oily sludge) and agricultural residue (rice husk) is presented. The quality of the products was evaluated by N2 adsorption–desorption isotherms and methylene blue (MB) adsorption tests. The asphaltene content of the oily sludge significantly affected the AC's specific surface area. The higher asphaltene content led to a higher specific surface area (2575m2/g) than that observed for the mixture with a lower asphaltene content (1849m2/g). Moreover, the ACs derived from mixtures of raw materials exhibited lower microporosity levels than those prepared with only oily sludge or rick husk. This may have been caused by the asphaltenes contained in oily sludge forming a carbon skeleton with the ash from the rice husk wrapped inside, generating more mesopores. The products prepared from the mixture also possessed far more oxygen-containing functional groups than AC produced from oily sludge alone. Meanwhile, the cellulose in the rice husk appeared to increase the amount of oxygen-functional groups in the AC products. The highest MB adsorption capabilities for the two AC samples were 588.24 and 757.58mg/g for AC-S1-3 and AC-S2-3, respectively. The Langmuir model fitted the experimental data better than the Freundlich model, suggesting the process can be described as homogeneous monolayer adsorption. X-ray diffraction and X-ray photoelectron spectroscopy data revealed the amorphous nature of the carbon in the AC products. Overall, mixtures of oily sludge and rice husk offer a promising option for preparing porous AC.

Porous Ni@C derived from bimetallic Metal–Organic Frameworks and its application for improving LiBH4 dehydrogenation

Hierarchically porous activated carbon (PAC) and Ni@C composite materials have been synthesized initially from MOF-5 and bimetallic Ni(II)-doped MOF-5s with the effective incorporation of Ni2+ ions into the frameworks. The products (PAC-1, Ni@C-1 and Ni@C-2) derived from MOFs contained rich micro/mesoporous structure and high specific surface areas (SSA): 2247, 919, and 484 m2 g−1, respectively. Interestingly, LiBH4 doped with Ni@C-1 showed the lowest onset temperature around 180 °C and fastest dehydrogenation kinetics. Results reveal that favorable synergistic effects of nanoconfinement and catalysis in Ni@C materials may improve hydrogen desorption kinetics, which demonstrates a promising strategy for the hydrogen-storage application of LiBH4.

Improvement of capacitive deionization performance via using a Tiron-grafted TiO2 nanoparticle layer on porous carbon electrode

A novel ion-selective inorganic-carbon composited electrode was designed to improve the performance of a capacitive deionization (CDI) process. Disodium 4,5-dihydroxy-1,3-benzenedisulfonate (Tiron) was grafted on the surface of titania nanoparticles, and a thin titania layer with a thickness of 10-12 μm was formed on porous activated-carbon (AC) electrode and used as the negative electrode in a CDI full cell. The resulting Tiron-grafted titania nanoparticles showed an excellent ion-exchange capacity (1.51 meq/g). As a result, the Tiron-titania/AC composited electrode was found to have improved desalination properties in terms of specific adsorption capacity, specific adsorption rate and current efficiency compared with the pristine CDI electrode. Improved desalination performance was attributed to a reduction in co-ion expulsion effect by ion-exchangeable functional groups in Tiron-grafted titania. In addition, the improved desalination performance through the introduction of a porous layer of Tiron-grafted titania was similar to that of the conventional membrane capacitive deionization (MCDI) using an ion-exchange membrane. From the results obtained, it has been experimentally proven that the use of Tiron-grafted TiO2/AC composite as the negative electrode in the CDI process is a simple and effective way to achieve high desalination performance.

Biomass-derived porous carbon modified glass fiber separator as polysulfide reservoir for Li-S batteries

Biomass-derived porous carbon has been considered as a promising sulfur host material for lithium-sulfur batteries because of its high conductive nature and large porosity. The present study explored biomass-derived porous carbon as polysulfide reservoir to modify the surface of glass fiber (GF) separator. Two different carbons were prepared from Oak Tree fruit shells by carbonization with and without KOH activation. The KOH activated porous carbon (AC) provides a much higher surface area (796 m2 g−1) than pyrolized carbon (PC) (334 m2 g−1). The R factor value, calculated from the X-ray diffraction pattern, revealed that the activated porous carbon contains more single-layer sheets with a lower degree of graphitization. Raman spectra also confirmed the presence of sp3-hybridized carbon in the activated carbon structure. The COH functional group was identified through X-ray photoelectron spectroscopy for the polysulfide capture. Simple and straightforward coating of biomass-derived porous carbon onto the GF separator led to an improved electrochemical performance in Li-S cells. The Li-S cell assembled with porous carbon modified GF separator (ACGF) demonstrated an initial capacity of 1324 mAh g−1 at 0.2 C, which was 875 mAh g−1 for uncoated GF separator (calculated based on the 2nd cycle). Charge transfer resistance (Rct) values further confirmed the high ionic conductivity nature of porous carbon modified separators. Overall, the biomass-derived activated porous carbon can be considered as a promising alternative material for the polysulfide inhibition in Li–S batteries.

Efficient Synthesis of 2-Methylfuran from Bio-Derived Furfural over Supported Copper Catalyst: The Synergistic Effect of CuOx and Cu

Transforming biomass into value‐added chemicals will reduce our reliance to fossil resources. This work reports the development of an activated carbon (AC) supported Cu‐based catalyst (Cu/AC) capable of efficiently convert bio‐derived furfural (FAL) into 2‐methylfuran (2‐MF), a valuable chemical and bio‐fuel. The Cu/AC catalyst was synthesized by a facile ultrasound‐assisted impregnation method with the aid of the reduction property of active carbon. The effect of synthetic conditions was investigated. It was found that the best performed catalyst (Cu/AC‐400/2) can be obtained from 2 h calcination at 400 °C. With Cu/AC‐400/2 as the catalyst, an almost 100% yield of 2‐MF can be obtained within 4 h under 170 °C reaction temperature and 3 MPa H2 pressure. Experimental evidence suggested that FAL was catalytically converted into 2‐MF via the formation of furfuryl alcohol (FOL) intermediate. Extensive characterization results indicated that the superior catalytic performance of Cu/AC‐400/2 catalyst could be attributed to the uniform sized and well dispersed Cu nanoparticles (NPs) with optimal proportions of Cu2+, Cu0 and Cu+ embedded on large surface area porous active carbon. Cycling test proved the synthesized catalyst could be reutilized during successive catalytic cycles because of Cu NPs distributed uniformly on the AC surface and the weak interaction between copper and support.

Black aspergillus-derived highly porous carbon fibers for capacitive applications

The increasing demand for high-performance supercapacitors has aroused great interest in fabricating materials with excellent specific capacitance and cycling stability. Here we report a porous activated carbon (PAC) derived from the pyrolysis of the renewable filamentous fungi in an inert atmosphere. PAC exhibits a high specific surface area of 1800 m2 g−1 with hierarchical structures. The N doped PAC electrode shows a remarkable gravimetric capacitance of 298 F g−1, and excellent cycling stability with 100% capacitance retention after 10,000 cycles. In addition, the rate capability of this material is pretty good and better than that of previously reported graphene and activated carbon-based materials. Furthermore, the as-assembled symmetric supercapacitor device exhibits good gravimetric energy density of 10.32 W h Kg−1. This work provides a new sustainable source of filamentous fungi for fabricating high performance porous carbon materials for supercapacitors.