Specific Surface Area Carbon Research Articles

Metal-carbon compositions as thermolysis products of complex compounds [Co(А)6]х[Fe(CN)6]у•nH2O (А = NH3, en/2)

The formation conditions of residual carbon have been studied for thermolysis in an inert atmosphere of double complex compounds of two groups of analogs: [Co(А)6][Fe(CN)6] and [Co(А)6]4[Fe(CN)6]3∙nH2O, where A = NH3, en/2. Isothermal experiments were carried out for extreme points of thermograms to obtain and analyze thermolysis products. Carbon was extracted from thermolysis products by leaching with hydrochloric acid, and its composition, thermal stability in air, specific surface area, and crystalline modification were investigated. The maximum carbon yield was for the compound [Co(NH3)6][Fe(CN)6], the largest specific surface area of carbon was 380 m2/g for [Co(en)3][Fe(CN)6]∙2H2O. The extracted carbon contains the admixtures of Co and Fe. The extracted carbon is stable when heated in air up to 450-500°С and burns completely up to 700°С. The carbon samples are largely graphitized.

Trichoderma bridges waste biomass and ultra-high specific surface area carbon to achieve a high-performance supercapacitor

Trichoderma is cultivated on a solid medium prepared from wheat straw and food waste. The harvested mixture is fully used to prepare high specific surface carbon. The carbon is further assembled into an electrode to assess its electrochemical performance as a supercapacitor. As adjusted by the activation temperature, the carbon derived at 800 °C displays an extremely high specific surface area of 3977.3 m2 g−1, and the carbon derived at 900 °C shows a large pore volume of 2.372 cm3 g−1. Correspondingly, an excellent specific capacitance of 409.7 F g−1 at a current density of 0.5 A g−1 can be achieved in a three-electrode system. The symmetric supercapacitor achieves a high energy density of 11.3 Wh kg−1 with a corresponding power density of 240.0 W kg−1, and exhibits a good capacitance retention of 99.2% after 10000 cycles at the current density of 5 A g−1 in a 6.0 mol L−1 KOH electrolyte. Based on these results, a novel low-cost path for preparing high-performance materials for energy storage applications is achieved from real-world biomass sources and provides new insights to realize the full utilization of biomass waste.

Vanadium -mediated ultrafine Co/Co9S8 nanoparticles anchored on Co-N-doped porous carbon enable efficient hydrogen evolution and oxygen reduction reactions.

Developing cost-effective, highly-active and robust electrocatalysts is of vital importance to supersede noble-metal ones for both hydrogen evolution reactions (HERs) and oxygen reduction reactions (ORRs). Herein, a unique vanadium-mediated space confined strategy is reported to construct a composite structure involving Co/Co9S8 nanoparticles anchored on Co-N-doped porous carbon (VCS@NC) as bifunctional electrocatalysts toward HER and ORR. Benefitting from the ultrafine nanostructure, abundant Co-Nx active sites, large specific surface area and defect-rich carbon framework, the resultant VCS@NC exhibits unexceptionable HER catalytic activity, needing extremely low HER overpotentials in pH-universal media (alkaline: 117 mV, acid: 178 mV, neutral: 210 mV) at a current density of 10 mA cm-2, paralleling at least 100 h catalytic durability. Notably, the VCS@NC catalyst delivers high-efficiency ORR performance in alkaline solution, accompanied with a quite high half wave potential of 0.901 V, far overmatching the commercial Pt/C catalyst. Our research opens up novel insight into engineering highly-efficient multifunctional non-precious metal electrocatalysts by a metal-mediated space-confined strategy in energy storage and conversion system.

Engineered biochars from organic wastes for the adsorption of diclofenac, naproxen and triclosan from water systems

Abstract The increased volume of produced toxic sewage sludge requires suitable management and utilization. Biochar production is an eco-efficient technology that uses toxic wastes towards highly efficient materials in pharmaceuticals removal from water. The management of sewage sludge towards engineered biochar can solve several problems: waste volume minimalization and obtaining of the novel highly efficient sorbents. The objective of this work was an evaluation of the affinity of sewage sludge-derived biochars towards selected pharmaceuticals in water systems. In order to achieve high specific surface area and high carbon content of biochar different carrier gas conditions, preparation temperatures and different raw materials were tested. The maximum adsorption capacity was following: diclofenac - 92.7 mg/g; triclosan - 113 mg/g and naproxen - 127 mg/g. The best fitting of the experimental results revealed mainly pseudo-second order model. The adsorption of diclofenac can occur via π-stacking interactions with the biochar surface mainly via Dubinin-Radushkevich model. Both interactions between the phenyl groups of triclosan molecules and phenol groups on biochar via hydrogen bonding, and non-covalent π-π stacking of aromatic groups of triclosan and biochar were responsible for monolayer surface coverage. The adsorption of naproxen was ascribed to Langmuir, Temkin and Dubinin-Radushkevich models and strong π–π electro-donor-acceptor interactions.

Monodispersed Ni2P nanodots embedded in N, P co-doped porous carbon as super stable anode material for potassium-ion batteries

Transition metal phosphides are considered as attractive anode materials of potassium-ion batteries owing to their high specific capacity and abundant reserves. However, the huge volume expansion and agglomeration of transition metal phosphides during the charge-discharge process always limit their practical application. In this work, we designed and prepared the composite of Ni2P and N, P co-doped porous carbon (Ni2P@NPC) by using biomass (gelatin) as raw material. Gelatin is rich in nitrogen element and has strong chelation with metal ions, resulting in uniform distribution of small Ni2P nanodots (5 nm in diameter) in N, P co-doped porous carbon. Moreover, the Ni2P@NPC composite was demonstrated to have large specific surface area and large carbon interlayer spacing, which could provide abundant reaction sites for K ions. The Ni2P@NPC has excellent electrochemical performance with a high capacity of 282mAhg−1 at 100 mA g−1 after 100 cycles, and it still remains 212mAhg−1 after 5000 cycles at 1 A g−1. In addition, the potassium-ion storage mechanism and the structure change of Ni2P@NPC during the charge-discharge cycles were investigated as well. This work provides a simple and environmentally friendly method to synthesize the high-performance anode materials for potassium-ion batteries.

Fabricating a modified biochar-based all-solid-state flexible microsupercapacitor using pen lithography

Despite an increasing interest in supercapacitors using biochar for fabricating eco-friendly energy modules, fabrication processes for most biochar-based supercapacitors are neither flexible nor easy. In this study, we fabricated an all-solid-state flexible MnO2/HNO3 pretreated biochar (NBC)/Poly(3,4-ethylenedioxythiophene) (PEDOT) composite microsupercapacitor (MSC) using pen lithography. Dispersion of biochar as ink for pen lithography was improved by HNO3 pretreatment. Specific surface area and graphitic carbon structure of the biochar were also increased by HNO3 pretreatment, resulting a high capacitance of electrochemical double layer. The fabricated MSC showed an increased pseudocapacitive behavior after adding an optimized amount of MnO2. Its capacitance was 76.6 F g−1 at 0.1 A g−1 of current density with an energy density of 14.0 Wh kg−1 at a power density of 53.1 W kg−1. The capacitive behavior of the fabricated MSC was stable over 500 bending cycles. The proposed MSC can be applied to fabricate flexible and eco-friendly energy modules.

Electrocatalytic Properties of {Mo-S}-Based Compounds with Regard to the Hydrogen Evolution Reaction and Application to PEM Water Electrolysis

Large amounts of molecular hydrogen (H2) are used in the chemical industry for a quite diverse set of applications, including gasoline refining, the synthesis of nitrogenous fertilizers, metal reduction, and many others.In this communication, we report on the synthesis of a family of thiomolybdic {MoS}-based electrocatalysts and their systematic electrochemical characterization for the hydrogen evolution reaction. The electrocatalysts, free of noble metals, have been further mixed with high specific surface area carbon agents (graphene and Vulcan) in view of catalytic ink formulation for implementation into high surface electrolysis proton exchange membrane cells. As a proof-of-concept, the electrocatalysts have been tested into areal electrolysis cells of 7 cm2. The results show high electrocatalytic efficiency and faradaic yields getting closer to what expected on metal Pt-based electrodes, making the thiomolybdic complexes good candidates for their implementation into practical electrolysis cells.The importance of this study is that it provides a full study, describing the synthesis and preparation of the electrocatalytic complexes and their physico-chemical and electrochemical characterization. As a proof-of-concept, our thiomolybdic based-electrode has been characterized into areal low pH solutions in large-scale electrolysis cells (7 cm2) towards practical applications in electrolyzers.Molecular molybdenum sulphide species have been extensively studied and considered as versatile chemical platform allowing to develop multifunctional catalytic materials, such as metal-substituted derivatives or coordination complexes, specifically designed with regard to the applied process.In order to further investigate the HER properties of such class of compounds, we report herein on the development of {Mo3S4}-based molecular HER catalysts, taking benefit of the well-known chemical properties of the aqua cluster [Mo3S4(H2O)9]4+, used as precursor in this work.The HER electrocatalytic performances of this hybrid catalyst have been investigated in both homogeneous and heterogenous phase, with the goal to design the first {Mo3S4}-based PEM (Proton Exchange Membrane) cathode for water electrolysis.The electrodes modified with Mo3S4 catalysts exhibit a high HER activity with an onset potential at −407 mV/SCE and a Tafel slope of −150 mV/dec. The potential at which a current density of 30 mA/cm2 was passed in 0.1 M H2SO4 (pH = 0.7) was found to be -0.5 V/SCE on Pt, -0.6 V/SCE on {Mo3S4}-based molecular HER catalysts + Vulcan. Finally, the complexes have been implemented at the cathode of PEM water electrolysis cells in place of platinum. The polarization curves have been measured and compared to those obtained with platinum. The HER overvoltage was increased by ~250 mV with the complex compared to Pt. These results show that {MoS}-based electrocatalysts are good candidates to replace Pt for the HER in PEM water electrolysis technology but optimization is still required and will be discussed.

Modeling and Optimization of Pollutants Removal during Simultaneous Adsorption onto Activated Carbon with Advanced Oxidation in Aqueous Environment.

The paper presents the results of studies on the modeling and optimization of organic pollutant removal from an aqueous solution in the course of simultaneous adsorption onto activated carbons with varied physical characteristics and oxidation using H2O2. The methodology for determining the models used for predicting the sorption and catalytic parameters in the process was presented. The analysis of the influence of the sorption and catalytic parameters of activated carbons as well as the oxidizer dose on the removal dynamics of organic dyes-phenol red and crystal violet-was carried out based on the designated empirical models. The obtained results confirm the influence of specific surface area (S) of the activated carbon and oxidizer dose on the values of the reaction rate constants related to the removal of pollutants from the solution in a simultaneous process. It was observed that the lower the specific surface area of carbon (S), the greater the influence of the oxidizer on the removal of pollutants from the solution. The proposed model, used for optimization of parameters in a simultaneous process, enables to analyze the effect of selected sorbents as well as the type and dose of the applied oxidizer on the pollutant removal efficiency. The practical application of models will enable to optimize the selection of a sorbent and oxidizer used simultaneously for a given group of pollutants and thus reduce the process costs.

The impact of pyrolysis temperature on physicochemical properties and pulmonary toxicity of tobacco stem micro-biochar

Biochars (BCs) are currently widely used, yet their impact on human health is mostly unknown. We generated micro-tobacco stem-pyrolysed BCs (mTBCs) at different pyrolysis temperatures and assessed pulmonary toxicity in normal human lung epithelial BEAS-2B cells. mTBCs generated at 350 °C (mTBC350) and 650 °C (mTBC650) were analysed and compared for physicochemical properties and adverse effects. Pyrolysis temperature had a significant influence on chemical composition, particle size, specific surface area and aromatic carbon structure. mTBC650 displayed a highly ordered aromatic carbon structure with smaller particle size, high surface area (20.09 m2/g) and high polycyclic aromatic hydrocarbon and metal content. This composition could promote reactive oxygen species accumulation accompanied by greater cytotoxicity, genotoxicity and epithelial barrier malfunction in cultured cells. Thus, the risk of pulmonary toxicity owing to micro-BCs (mBCs) is affected by pyrolysis temperature. Long-term exposure to mBCs produced at high temperatures may lead to or exacerbate pulmonary disease.

A facile and general procedure to hyperporous carbons: carbonization of organic zinc salts

A facile, one step procedure is proposed to prepare hyperporous carbons by using zinc organic salts as precursors. The volatile character of zinc at high temperature not only leads to high specific surface area, but also avoids the post-washing step after carbonization. The pore texture of the carbons can be easily turned by using different precursor and the factors that affect the porosity are examined in detail. It is found that a precursor with a high Zn/C ratio and chain-like structure tends to form high specific surface area carbons. The carbons show high potential when used for CO2 capture and electrode material of supercapacitor. Especially for Zn–C–C derived from zinc citrate, shows a high specific surface area of 2933 cm3 g−1, a high CO2 uptake of 88 cm3 g−1 at 298 K and a high capacitance of 260 F g−1 at a current density of 1 A g−1. We believe that by choosing proper Zn organic salts precursors, carbonaceous materials with properties that surpass those reported here can be prepared and more application fields are waited to be extended by these carbons.

Non‐metallic printed circuit board waste derived carbon for the supercapacitor electrode material

Highly specific surface area carbon materials derived from the waste printed circuit board (WPCB) for supercapacitor electrode material are feasibly prepared via microwave carbonisation and KOH activation process with controlled activation temperature. The effect of activation temperature on the pore structure and the electrochemical performance of the products are studied. The results demonstrate that the appropriate pore structure plays an important role in the application of supercapacitor. The electrochemical performance tests show that the specific capacitance of WPCB-800 can reach 134.2 F g−1 at current density of 200 mA g−1, and the capacity retention rate is 96.2% after 2000 cycles.

Ethanol and KOH co-pretreatment towards ultra-high specific surface area carbons for high-rate and high-energy supercapacitors.

A new avenue for fabricating ultra-high specific surface area (SSA) carbons with hierarchical porous and excellent energy storage ability is achieved from the biomass-waste of pitaya peel with the pre-treating process by ethanol and KOH to optimize the microstructure and porosity, displaying excellent supercapacitance in different electrolytes.

Numerical and experimental study of oil transfer in laminated shale

Lamination is ubiquitous in shale oil reservoirs and significantly influences the oil transfer process. Understanding oil transfer in laminated shale is important for shale oil reservoir development. Therefore, a mathematic model is developed to describe the processes involved in vacuum-imbibition tests. In constructing the mathematic model, viscous flow in inorganic pore, oil adsorption, and absorption in organic matter, and oil diffusion through organic matter surface and interior are considered. In addition, a crucial link between the model and physical characteristics of shale (specific surface area, clay content, and total organic carbon content) is established. The results reveal that the saturation capacities of free oil, adsorbed oil, and absorbed oil in shale depend on the porosity, specific surface area and volume of organic matter, respectively. The oil contents in the adsorption and absorption phase range from 2.2% to 8.3% and 41.8% to 51.4% of the total oil content for the three samples in this study, respectively. When the equilibrium time is used to determine the oil transfer in shale, a larger specific surface area, a smaller thickness of lamination, and smaller volume fractions of organic–clay matrix to total volume of the samples hasten oil transfer. Also, an ideal vacuum-imbibition process of oil in laminated shale is discussed. The results reveal that oil diffusion through the surface of organic matter accelerates the oil transfer in laminated shale. However, the effect of the effectivity diffusion coefficient of oil in the adsorption phase (Ds) on the oil transfer is smaller than that of the effectivity diffusion coefficient of oil in the absorption phase (Dd).

H3IDC-assisted synthesis of mesoporous ultrafine Co3O4/N-doped carbon nanowires as a high rate and long-life anode for Lithium-ion batteries

A facile low-temperature hydrothermal method is developed to synthesize the Co-based coordination polymer precursor with ultrafine one-dimensional (1D) nanostructure by using 4,5-imidazole-dicarboxylic acid (H3IDC) as the ligand. The precursor is transformed into mesoporous ultrafine Co3O4/NC nanowires through calcined process. The mesoporous ultrafine Co3O4/NC nanowires are all less than 20 nm in diameter, and constructed by interconnecting N-doped carbon coated Co3O4 nanocrystals. As an anode in Lithium-ion batteries, the as-prepared Co3O4/NC nanowires electrode shows an outstanding rate capability and long-cycle stability. At 0.1 A g−1, it displays an initial capacity of 1358 mA h g−1 and maintains a reversible capacity of 1294 mA h g−1 after 500 cycles. Meanwhile, it has a reversible capacity of 897 mA h g−1 after 1000 cycles at 1.0 A g−1. Moreover, the volume specific capacity of Co3O4/NC nanowires electrode is 1121.1 mA h cm−3 after 1000 cycles at 1.0 A g−1. The excellent lithium storage performance is attributed to the synergistic effect of ultrafine nanowires, abundant mesopores, large specific surface area, pseudocapacitive behavior and continuous high-conductivity N-doped carbon coating.

Study on co-combustion characteristics of hydrochar and anthracite coal

Non-isothermal thermogravimetric analysis was employed to study the combustion reaction behavior of three different hydrochars and one anthracite in the paper. The particle size distribution analysis, scanning electron microscopy, specific surface area and Raman spectroscopy were also used to observe and characterize physiochemical properties. The Coats-Redfern kinetic model method was used to calculate the activation energy of different combustion reactions. The results showed that the combustion of fiber reject had a more effective combustion property than the other two hydrochars. The main reason was that fiber reject had higher specific surface area and lower carbon microcrystalline structure. Meanwhile, the co-combustion of different hydrochars with coal had similar combustion trends, and with the increase of hydrochar proportion, the combustion rate was higher. The results of the kinetic calculation correspond to this conclusion. It can be found that as the proportion of the three hydrochar increased, the activation energy of two stages gradually decreased.

Estimating the mineral surface area of soils by measured water adsorption. Adjusting for the confounding effect of water adsorption by soil organic carbon

AbstractSpecific surface area can be a strong predictor of organic carbon (SOC) contents in soils. Specific surface area can be estimated reliably and cost‐effectively from water adsorption by air‐dry soil samples, but SOC itself can also adsorb water. For estimating the mineral component of specific surface area, it is, therefore, necessary to exclude water‐adsorption by SOC. Here, we refer to “apparent specific surface area” for measurements that include water adsorption by both mineral soil and SOC. We used a mathematical approach to estimate water adsorption by SOC so that this component can be subtracted from measurements of apparent specific surface area.We used a dataset of apparent specific surface area and soil carbon at seven depths from 50 soil cores collected from a research farm in the Manawatu region in New Zealand. Both apparent specific surface area and SOC content decreased with soil depth with very high correlation (r2 = 0.98). We estimated the SOC contribution to apparent specific surface area from the slope of the relationship between changes in apparent specific surface area and SOC content. For our soils, the SOC contribution to apparent specific surface area was estimated as 0.43 ± 0.02 m2 mgC−1. This parameter allows apparent specific surface area measurements to be corrected for the water adsorption by SOC to calculate the functionally relevant mineral specific surface area.Highlights Soil surface area can be estimated from the H2O content of air‐dry soil but SOC also adsorbs H2O. We developed a mathematical approach to estimate water adsorption by SOC. We estimated the contribution of SOC to apparent specific surface area as 0.43 ± 0.02 m2 mgC−1. Mineral specific surface area can be inferred by subtracting SOC‐based H2O adsorption.

Synergistic effect by high specific surface area carbon black as secondary filler in silica reinforced natural rubber tire tread compounds

The partial replacement of silica by high specific surface area and high structure Carbon Black (CB) N134 as secondary filler, keeping the same total filler content at 55 phr, shows a clear synergistic effect on overall performance. At low content of CB, i.e. in the range of 0–36 wt% of CB relative to total filler amount, the Payne effect and tan delta at both 0 °C and 60 °C change marginally, but thereafter gradually increase. Cure times are shortened in the presence of CB, facilitating an increase of productivity. Bound rubber content and mechanical properties show an optimum at 18 wt% of CB relative to total filler amount or at a ratio of silica/CB 45/10 phr. With regard to tire performance as indicated by the laboratory test results, the abrasion resistance, wet grip and ice traction can therefore be enhanced while maintaining the tire rolling resistance at the optimum level for this silica/CB ratio.

HNBR-based composite for seals used in coolant fluids: Swelling related to different silicates at high temperature

The effects of five fillers (two synthetic calcium silicates, one natural calcium silicate, talcum and a low specific surface area carbon black) filled with hydrogenated acrylonitrile butadiene rubber (HNBR) for possible use in seal for coolant fluids were developed by hardness, mechanical properties and hot air aging properties. Fluid blends were used to simulate the degraded OAT coolant. The swelling mechanism of HNBR vulcanizates was investigated by XRD, SEM, EDS, FT-IR and GC-MS. The results indicated that the filler with high specific surface area was easier to combine with HNBR. Hot air aging tests revealed a relatively high heat resistance and can meet the practical requirements. 2-ethylhexanoic acid hydrolyzed by sodium 2-ethylhexanoate as corrosion inhibitor react with silicate fillers in rubber to form 2-ethylhexanoate into the coolant, thus the network structure of rubber destroyed, while 2-ethylhexanoic acid and ethylene glycol diethyl-hexanoate as well as a small amount of ethylene glycol and water immersed into rubber. Higher crystallinity and lower specific surface area made natural CaSiO3 an efficient intrinsic base reserve to scavenge acidic products and effectively reduce the swell of filled HNBR.

Equilibrium studies on batch adsorption of alizarin red in aqueous solution using activated carbons derived from orange peels

Adsorption has been one of the most preferred methods for the removal of dyes from aqueous solutions due to its simplicity and economic advantages. In this research, activated carbon prepared from orange peels has been characterized using Boehm titration which revealed the surface as having 7.70 mmol/g and 3.64 mmol/g total acidic and basic sites respectively. Scanning Electron Microscope (SEM) imaging showed that the adsorbent had heterogeneous surface morphology while the pH of zero point charge (pHzpc) of the adsorbent was found to be 3.6. Furthermore, Sear’s titration has shown that the activated carbon specific surface area was 791.1 m2 g - . 1The influence of various experimental parameters have been probed and optimized. The optimized conditions were set for the study of adsorption equilibrium and the experimental data were treated using Langmuir, Freundlich, Dubnin-Radushkevic (D-R) and Halsey isotherm models. However, all the four isotherm models were in good fit with the data obtained as indicated by the regression coefficients (R2 value) of 0.944 for the Langmuir isotherm, 0.993 for both Freundlich and Halsey models, and 0.980 for D-R model. The maximum monolayer coverage capacity (qm) was determined to be 11.5 mg/g at room temperature, which is higher than some presented in the previous literature.Keywords: Adsorption, Alizarin red, Orange peels, Textile dyes, Waste water, Adsorption isotherm

Tuning surface properties of N-doped carbon with TiO2 nano-islands for enhanced phenol hydrogenation to cyclohexanone

Abstract ZIF-derived N-doped carbon (CN) materials were modified in this work by TiO2 nano-islands with oxygen vacancies (OV) through a sol-gel method and subsequent thermal treatment. By loading Pd nanoparticles (NPs) on CN@TiO2, Pd@CN@TiO2 catalysts were fabricated. Superior catalytic performance of Pd@CN@TiO2 was found in the selective phenol hydrogenation to cyclohexanone, with a TOF of 30.1 h−1, 2.2-fold as high as that of Pd@CN. The synergistic effect of CN and TiO2 nano-islands was responsible for the superior catalytic performance. More OV was generated due to the high specific surface area of CN. At the same time, CN could also enhance the hydrophilicity, and adsorb more phenol in non-planar fashion. The TiO2 nano-islands with OV could improve the Pd dispersion, make more Pd element on the support surface, strengthen the antioxidizability of Pd and induce electron-rich Pd NPs. Furthermore, the as-fabricated Pd@CN@TiO2 showed good recyclability in the phenol hydrogenation, and also exhibited excellent catalytic performance in the catalytic hydrogenation of phenol with diverse functional groups. These findings provide the feasibility of using the high-performance catalysts for the hydrogenation of phenol derivatives.