Carbon Letters 2021 KCI Impact Factor : 0.52

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pISSN : 1976-4251 / eISSN : 2233-4998

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2021, Vol.31, No.4

  • 1.

    Crumpled and porous graphene for supercapacitor applications: a short review

    Mathew Elma Elizaba , Balachandran Manoj | 2021, 31(4) | pp.537~555 | number of Cited : 1
    Abstract
    Research on Graphene and its importance in the field of energy conversion and storage devices such as fuel cells, batteries, supercapacitors and solar cells has gained momentum recently. It is studied to be the most suitable electrode material for enhanced performance of supercapacitors in terms of charge–discharge cycles, specific capacitance, high power and energy densities and so on, specifically due to its high conductivity and large theoretical surface area. Unfortunately, it posits lot of challenges due to its irreversible stacking between the individual sheets resulting in the decrease in the Specific Surface Area (SSA) compared to the theoretically reported values. Numerous studies have been carried out to prevent this stacking in order to increase the surface area, thereby being a more suitable material for the manufacture of electrodes for supercapacitors as its capacitance greatly depends on the electrode material. To solve this problem, the conversion of two-dimensional graphene sheets to three-dimensional crumpled graphene structure has been verified to be the most effective approach. The study of crumpled graphene has been one of the recent trends in the field of energy storage applications in consumer electronics and hybrid vehicles as the process of crumpling can be controlled to suit the prospective device applications.
  • 2.

    Carbon substrates: a review on fabrication, properties and applications

    Ramesh M. , Rajeshkumar L. , Bhoopathi R. | 2021, 31(4) | pp.557~580 | number of Cited : 0
    Abstract
    Carbon lives along with us in our daily life and has a vital role to play. It is present in the air and within all living organisms. Due to its handheld advantage in nano-properties that are utilized in many applications, carbon substrates came under limelight during the recent decades. Carbon substrates are most widely used in cancer detection, catalysis, bio-sensing, adsorption, drug delivery, carbon capture, hydrogen storage, and energy. Alongside, composite materials with carbon as an additive are also developing rapidly in applications like infrastructures, automobile, health care, consumer goods, etc. which became an integral chunk of our life. In this paper diferent types of carbon substrates and its applications, properties of the substrates were reviewed. The applications and methods of synthesis of carbon substrates are also dealt with a broad perspective.
  • 3.

    Nitrogen release and pore formation through KOH activation of nitrogen-doped carbon materials: an evaluation of the literature

    Wabo Samuel Ghomsi , Klepel Olaf | 2021, 31(4) | pp.581~592 | number of Cited : 0
    Abstract
    The simultaneous use of KOH and nitrogen to manufacture carbon materials provides these materials with properties that the presence of only one of these additives would not give them, such as high porosity and reactivity. However, it is difcult to obtain nitrogen-doped carbon materials with both high porosity and high nitrogen content, as the KOH signifcantly reduces the nitrogen content. In this review the complex relationships between nitrogen content and nitrogen precursor amount, KOH amount and the activation temperature are discussed, with a focus on the diferent N-functional groups and the porosity of the fabricated carbons. Generally, increasing activation temperature and increasing KOH amount decrease the nitrogen content due to reactions with the N-containing substructures of carbon, resulting in the release of nitrogen as N2, HCN and other N gases. Increasing these parameters can also result in the reduction of pyridine-N while the amount of quaternary-N increases simultaneously. Besides this, an increase in the amount of nitrogen precursor leads to an increase in the porosity of N-doped materials. However, too high amounts of the nitrogen precursor generate an excess of nitrogen which blocks the pore system and consequently reduces the porosity of the doped carbons.
  • 4.

    Nanostructures and nanomechanical properties of ion-irradiated HOPG

    Zhou Yuying , Wang Ying , Lei Qiantao and 3 other persons | 2021, 31(4) | pp.593~599 | number of Cited : 0
    Abstract
    Highly Oriented Pyrolytic Graphite (HOPG) was half covered using aluminum foil and exposed to irradiation with 70 keV C+ ions at room temperature (~25 ℃). The surface layer (height=178.3±4.7 nm) of the irradiated area was destroyed, many nano-sized dendritic protrusions were observed and smooth inner layer was exposed. The peak area ratio (ID/IG) in Raman spectra increased after ion irradiation, indicating that a change in atomic structure and transformation from the sp2 to sp3 phase. The mechanical properties were explored using atomic force microscopy in peakforce mode, which revealed that the Young’s modulus of the exposed inner layer was similar to unirradiated area, while the Young’s modulus of the dendritic protrusions was higher. There fndings provid
  • 5.

    Enhancing the performance of supercapacitor electrode from chemical activation of carbon nanofibers derived Areca catechu husk via one-stage integrated pyrolysis

    Taer Erman , Febriyanti Friska , Mustika Widya Sinta and 3 other persons | 2021, 31(4) | pp.601~612 | number of Cited : 0
    Abstract
    A carbon nanofber was produced from the Areca catechu husk as a supercapacitor electrode, utilizing a chemical activation of potassium hydroxide (KOH) at diferent concentrations. One-stage integrated pyrolysis both carbonization and physical activation were employed for directly converting biomass to activated carbon nanofber. The morphology structure, specifc surface area, pore structure characteristic, crystallinity, and surface compound were characterized to evaluate the infuence on electrochemical performance. The electrochemical performance of the supercapacitor was measured using cyclic voltammetry (CV) through a symmetrical system in 1 M H2SO4. The results show that the KOH-assisted or absence activation converts activated carbon from aggregate into a unique structure of nanofber. The optimized carbon nanofber showed the large specifc surface area of 838.64 m2 g−1 with the total pore volume of 0.448 cm3 g−1, for enhancing electrochemical performance. Benefcial form its unique structural advantages, the optimized carbon nanofber exhibits high electrochemical performance, including a specifc capacitance of 181.96 F g−1 and maximum energy density of 25.27 Wh kg−1 for the power density of 91.07 W kg−1. This study examines a facile conventional route for producing carbon nanofber from biomass Areca catechu husk in economical and efcient for electrode supercapacitor.
  • 6.

    Enhanced electrical conductivity of doped graphene fiber via vacuum deposition

    Park Beum Jin , PARK, HOSEOK | 2021, 31(4) | pp.613~618 | number of Cited : 0
    Abstract
    Graphene fber is considered as a potential material for wearable applications owing to its lightness, fexibility, and high electrical conductivity. After the graphene oxide (GO) solution in the liquid crystal state is assembled into GO fber through wet spinning, the reduced graphene oxide (rGO) fber is obtained through a reduction process. In order to further improve the electrical conductivity, herein, we report N, P, and S doped rGO fbers through a facile vacuum difusion process. The precursors of heteroatoms such as melamine, red phosphorus, and sulfur powders were used through a vacuum difusion process. The resulting N, P, and S doped rGO fbers with atomic% of 6.52, 4.43 and 2.06% achieved the higher electrical conductivities compared to that of rGO fber while preserving the fbrious morphology. In particular, N doped rGO fber achieved the highest conductivity of 1.11 ×104 S m−1, which is 2.44 times greater than that of pristine rGO fber. The heteroatom doping of rGO fber through a vacuum difusion process is facile to improve the electrical conductivity while maintaining the original structure.
  • 7.

    Exploration on reduced graphene oxide/strontium pyro niobate electrode material for electrochemical energy storage applications

    Kumar M. Infant Shyam , Kirupavathy S. Shahil , Shalini S. | 2021, 31(4) | pp.619~633 | number of Cited : 0
    Abstract
    Most recently, graphene-related composite-modifed electrode surfaces are been widely employed to improve surface interactions and electron transfer kinetics. Hydrothermally prepared strontium pyro niobate (SPN) and reduced graphene oxide/ strontium pyro niobate (RGOSPN) nanostructures reveal excellent morphology. X-ray difraction analysis of SPN and RGOSPN agree with standard data. Thermogravimetry–diferential scanning calorimetry analyses show that RGOSPN has higher thermal stability than SPN. In addition, from the polarization–electric feld (P–E) loop measurements, the estimated value of remnant polarization (Pr ) and coercive electric feld (Ec) of SPN are 0.039 µC cm−2 and −2.90 kV cm−1 and that of RGOSPN nanocomposite are 0.0139 µC cm−2 and −2.04 kV cm−1. Cyclic voltammetry measurements show that RGOSPN nanocomposite manifests the possibility of electrochemical reversibility beyond long cycles without change in performance. The redox cycle reveal that RGOSPN can be used as part of a composite electrode for hybrid capacitors dynamic conditions. Moreover, the specifc capacitance of SPN and RGOSPN was calculated using galvanostatic charge–discharge (GCD) technique. The observed energy density of 9.1 W h kg−1 in RGOSPN is higher when compared with previous reported values.
  • 8.

    Enhanced electrochemical performances of activated carbon (AC)-nickel-metal organic framework (SIFSIX-3-Ni) composite and ion-gel electrolyte based supercapacitor

    Leekyuseok , Seo Ye Ji , Jeong Hyeon Taek | 2021, 31(4) | pp.635~642 | number of Cited : 0
    Abstract
    In this study, we investigated that the activated carbon (AC)-based supercapacitor and introduced SIFSIX-3-Ni as a porous conducting additive to increase its electrochemical performances of AC/SIFSIX-3-Ni composite-based supercapacitor. The AC/SIFSIX-3-Ni composites are coated onto the aluminum substrate using the doctor blade method and conducted an ion-gel electrolyte to produce a symmetrical supercapacitor. The electrochemical properties of the AC/SIFSIX-3-Ni composite-based supercapacitor are evaluated through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge/discharge tests (GCD). The AC/SIFSIX-3-Ni composite-based supercapacitor showed reasonable capacitive behavior in various electrochemical measurements, including CV, EIS, and GCD. The highest specifc capacitance of the AC/SIFSIX-3-Ni composite-based supercapacitor was 129 F g−1 at 20 mV s−1.
  • 9.

    Hierarchical porous carbons derived from corncob: study on adsorption mechanism for gas and wastewater

    Feng Zhi-Yuan , Meng Long-Yue | 2021, 31(4) | pp.643~653 | number of Cited : 0
    Abstract
    Hierarchical porous carbons (HPCs) have been successfully prepared by a facile carbonization and subsequent CO2 activation process using corncob as a natural carbon precursor and Mg(C2H3O2)2 as a MgO nano-template precursor. The prepared corncob-based hierarchical porous carbons (C-HPCs) with desirable micropores and mesopores feature the excellent absorbency of gas (i.e., CO2 and CH4) and solution (i.e., methylene blue (MB)). Increasing the ratio of Mg(C2H3O2)2/corncob enlarged the specifc surface area up to 1004 m2 /g, micropore and mesopore volumes, CO2, CH4, and MB adsorption capacities (112, 31 and 230 mg/g after 325 min, respectively). The results indicated that the pore structures of C-HPCs can be easily and suitably controlled by the amount of the template precursor and CO2 activation efecting concurrently, which leads to fascinating adsorption capacity for CO2, CH4, and MB.
  • 10.

    Investigation of hydrogen adsorption behavior of graphene under varied conditions using a novel energy-centered method

    Luhadiya Nitin , Kundalwal S. I. , Sahu S. K. | 2021, 31(4) | pp.655~666 | number of Cited : 0
    Abstract
    The adsorption of molecular hydrogen on the monolayer graphene sheet under varied temperature and pressure was studied using molecular dynamics simulations (MDS). A novel method for obtaining potential energy distributions (PEDs) of systems was developed to estimate the gravimetric density or weight percentage of hydrogen. The Tersof and Lennard–Jones (LJ) potentials were used to describe interatomic interactions of carbon–carbon atoms in the graphene sheet and the interactions between graphene and hydrogen molecules, respectively. The results estimated by the use of novel method in conjunction with MDS developed herein were found to be in excellent agreement with the existing experimental results. The efect of pressure and temperature was studied on the adsorption energy and gravimetric density for hydrogen storage. In particular, we focused on hydrogen adsorption on graphene layer considering the respective low temperature and pressure in the range of 77–300 K and 1–10 MPa for gas storage purpose which indicate the combination of optimal extreme conditions. Adsorption isotherms were plotted at 77 K, 100 K, 200 K, and 300 K temperatures and up to 10 MPa pressure. The simulation results indicate that the reduction in temperature and increase in pressure favor the gravimetric density and adsorption energies. At 77 K and 10 MPa, the maximum gravimetric density of 6.71% was observed. Adsorption isotherms were also analyzed using Langmuir, Freundlich, Sips, Toth, and Fritz–Schlunder equations. Error analysis was performed for the determination of isotherm parameters using the sum of the squares of errors (SSE), the hybrid fractional error function (HYBRID), the average relative error (ARE), the Marquardt’s percent standard deviation (MPSD), and the sum of the absolute errors (SAE).
  • 11.

    Preparation of activated carbon spheres and their electrochemical properties as supercapacitor electrode

    An Xin , Xing Guannan , Wang Jing and 3 other persons | 2021, 31(4) | pp.667~676 | number of Cited : 0
    Abstract
    The carbon spheres (CSs) synthesized by an ultrasonic-spray pyrolysis method were activated for supercapacitor electrode. There are plenty of cracks on the surface of the activated carbon spheres (ACSs), which expend with increasing the activation temperature and activator dosage. The specifc capacitance of ACSs increases with the activation temperature and activator dosage and reach to maximal value at certain conditions. Importantly, the ACS sample activated at relatively low activation temperature (600 °C) and 7 of mass ratio of KOH to CSs has the highest specifc capacitance (about 209 F g−1 at 50 mA g−1 of current density) and indicates the excellent cycling stability after 1000 consecutive charge–discharge cycles. Furthermore, the graphene sheets could be found in the samples that were activated at 1000 °C. And the electrode prepared by the sample has the very low series resistance because of the excellent conductivity of the formed graphene sheets.
  • 12.

    Poly(amidoamine) dendrimer-grafted carbon nanotubes as a hybrid multifunctional curing agent for epoxy-modified polyurethane

    Izadi Mohammadreza , Mardani Hanieh , Roghani-Mamaqani Hossein and 1 other persons | 2021, 31(4) | pp.677~688 | number of Cited : 0
    Abstract
    Carbon nanotube (CNT) grafted with hyperbranched poly(amidoamine) (PAMAM) dendrimer (CNTD) were used as a multifunctional curing and composite agent of polyurethane (PU) terminated with epoxy units. Amino-functionalized CNT was used as the core for grafting the frst generation of PAMAM dendrimer by sequential addition of methyl acrylate and ethylenediamine. Two diferent epoxy-terminated PUs (PUB and PU-PMDA) were prepared from the reaction of poly(ethylene glycol), excess amounts of hexamethylene diisocyanate, and diferent chain extenders (1,4-butanediol for PUB and pyromellitic dianhydride (PMDA) for PU-PMDA), and subsequent end group transformation of the isocyanate groups to epoxy functionalities using glycidol. Fourier transform infrared spectra and thermogravimetric analysis (TGA) results showed that CNTD was successfully prepared. TGA thermograms revealed that thermal decomposition of composites were carried out in two main steps related to the soft and hard segments. In addition, char content and thermal stability of the composites were increased with increasing the CNTD content. Most importantly, the PMDA chain extender resulted in high thermal stability of the epoxy-terminated PU composites. X-ray difraction and scanning and transmission electron microscopies presented morphological and structural properties of nanotubes and hybrid composites.
  • 13.

    Smooth surface induced glossy appearance of freestanding multiwall carbon nanotube sheet

    Susantyoko Rahmat Agung , Aldarmaki Noura , Karam Zainab and 2 other persons | 2021, 31(4) | pp.689~693 | number of Cited : 0
    Abstract
    Carbon nanotube (CNT) structures reported in the literature often have a black color with low refectance and matt surface appearance. Only a few papers reported the high refectance and glossy appearance of the CNT surface on a substrate. To our knowledge, no one has reported the glossy appearance of freestanding CNT. Herein, we have successfully fabricated a freestanding multi-walled CNT sheet with a glossy or mirror-like surface appearance. Raman spectroscopy confrmed that both matt and glossy freestanding CNT sheets have the same chemical composition. We found that the glossy freestanding CNT sheet has a relatively fat surface morphology compared to matt freestanding CNT sheet, as seen in the atomic force microscopy results. We attributed the glossy appearance due to a relatively fat surface morphology of the freestanding CNT sheet.
  • 14.

    Facile synthesis of nitrogen-doped carbon dots (N-CDs) and N-CDs/NiO composite as an efficient electrocatalyst for oxygen evolution reaction

    Kou Xiaoli , Xin Xin , Zhang Yan and 1 other persons | 2021, 31(4) | pp.695~706 | number of Cited : 0
    Abstract
    Nitrogen-doped carbon dots (N-CDs), derived from the biomass (anthocyanin), are the novel additive to the nanocarbon materials, which is expected to bring a wide spectrum of novel applications. Moreover, metallic oxides are emerging for their unique potential for electrocatalysis. Herein, we report the synthesis of N-CDs for the selective detection of Fe3+ with a limit of detection of 2.57 μM in the range of 5–60 μM using ethylenediamine and H2O2 by a hydrothermal method. The obtained N-CDs displayed a spherical morphology with a particle size range of 2–7 nm and emitted blue luminescence at 394 nm under excitation at 319 nm. Meanwhile, we have demonstrated the fabrication of cost-efcient electrocatalysts for oxygen evolution reaction (OER) in an alkaline medium, employing N-CDs. Owing to the successful incorporation of N-CDs into NiO nanospheres, the resulting N-CDs/NiO with large surface areas, fast charge transfer, and increased conductivity vastly improved the catalytic activity. Remarkably, the optimal of N-CDs/NiO composite requires the overpotential of only 380 mV at a current density of 10 mA cm−2 and a relatively low Tafel slope of 57.96 mV dec−1 compared with pure NiO. These results open up a facile route for the application of N-CDs and ofer prospects for CD-metal hybrids as high OER catalysts in electrochemical energy devices.
  • 15.

    Electrical percolation and fluidity of conductive recycled mortar cement: graphite powder: recycled sand with addition of industrial waste carbon fiber

    Espinoza-Moreno C. A. , Rodriguez-Rodriguez M. , Pellegrini-Cervantes M. J. and 5 other persons | 2021, 31(4) | pp.707~720 | number of Cited : 0
    Abstract
    The use of recycled materials, such as the fne recycled aggregate made from concrete waste and carbon fber (CF) product of industrial waste, for the manufacture of conductive recycled mortars (CRM), transforms the mortar base cement normally made with cement:sand in a sustainable multifunctional material, conferring satisfactory mechanical and electrical properties for non-structural uses. This action provides ecological benefts, reducing the use of natural fne aggregates from rivers and the amount of concrete waste deposited in landflls resulting from construction waste. In this investigation the efect of the addition of CF on electrical properties in hardened, wet and dry state, electric percolation in dry state and fuidity of the wet mixture of a cement based CRM was evaluated: fne recycled aggregate: graphite powder, CRM specimens with dimensions of 4×4×16 cm. were manufactured for 3, 7 and 28 days of age and sand/cement ratios=1.00, graphite/cement=1.00, water/cement=0.60 and CF=0.1, 0.3, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0% compared to the weight of cement. The results demonstrated the efect of the addition of CF in CRM, reducing fuidity of the mixtures due to the opposition generated by its physical interaction of CF with recycled sand or recycled fne aggregate and graphite powder (GP), in its case, placing the electric percolation percolation at 0.30% and 0.45% of CF for CRM with and without GP, respectively. Increases in electrical conductivity (EC) without the presence of GP are defned by the contact between the CF and the conductive paths formed. In contrast, with the presence of GP, the EC is defned by the contact between the CF and the GP simultaneously, forming conductive routes with greater performance in its EC.
  • 16.

    Valorization of spent activated carbon in glycerine deodorization unit for methylene blue removal

    Hui Tang Shu , Zaini Muhammad Abbas Ahmad | 2021, 31(4) | pp.721~728 | number of Cited : 0
    Abstract
    Spent Calgon Filtrasorb activated carbon (SAC) from glycerine deodorization unit was evaluated for the removal of methylene blue (MB). The SAC was used without further modifcation. The SAC was characterized for BET surface area, pH, pHpzc and FTIR to determine the textural and chemical properties of SAC. The batch adsorption study of MB was carried out under diferent initial concentrations (5–500 mg/L), pH (2–11) and contact time (0–200 h). The SAC was found to have high BET surface area, pore volume and average pore diameter of 735 m2 /g, 0.292 cm3 /g and 2.56 nm, respectively. The properties of SAC contributed to high MB adsorption capacity of 283 mg/g. The equilibrium data ftted well with Langmuir model, indicating monolayer adsorption; while the activation energy (Ea) of Dubinin–Radushkevitch (D–R) model is lower than 8 kJ/mol, signifying physisorption. The adsorption kinetics was best illustrated by pseudo-second-order model, while the intraparticle difusion and Boyd models suggested that flm difusion is the rate-controlling step. These fndings showed that Calgon Filtrasorb SAC from glycerine deodorization unit can be potentially reused an adsorbent for the removal of dyes.
  • 17.

    A simple nonenzymatic glucose sensor based on coconut shell charcoal powder-coated nickel foil electrode

    Edakkaparamban Shuaib , Parasseri Muhammed Shafi , Yogesh Gaurav Kumar and 2 other persons | 2021, 31(4) | pp.729~735 | number of Cited : 0
    Abstract
    In this work, a simple nonenzymatic glucose sensor has been proposed based on coconut shell charcoal (CSC) modifed nickel foil as working electrode in a three-electrode electrochemical cell. Charcoal was prepared by the pyrolysis of coconut shells. The most important advantages of coconut shells are cost-efectiveness and their abundance in nature. The morphology and phase of the CSC powder were characterized by scanning electron microscopy and X-ray difraction. The electrochemical performance of the CSC powder coated Nickel foil electrode was investigated by cyclic voltammetry and chronoamperometry. The sensor shows a higher sensitivity of 2.992 mA cm−2 mM−1 in the linear range of 0.5–5.5 mM and slightly lower sensitivity of 1.1526 mA cm−2 mM−1 in the range of 7–18.5 mM glucose concentration with a detection limit of 0.2 mM. The anti-interference property of CSC powder also was investigated and found that the response of interfering species was less signifcant compared to glucose response. The proposed sensor ofers good sensitivity, wide linear range, and a very low response to interfering biomolecules.
  • 18.

    Camphor leaf-derived activated carbon prepared by conventional physical activation and its water adsorption profile

    Chairunnisa , Takata N. , Thu K. and 3 other persons | 2021, 31(4) | pp.737~748 | number of Cited : 0
    Abstract
    Preparation of activated carbon from biomass residue with conventional steam activation was conducted to fnd the alternative raw materials for meeting the high demand for low-cost porous material in the desiccant application. In this study, activated carbons were produced from dead camphor leaves using two-step methods at diferent preparation temperatures. The characterization results revealed that the prepared activated carbons have a surface area of 700 m2 /g, with 75% of microporosity. The water vapor sorption study reported that the water uptake of camphor leaf-based activated carbons was strongly afected by the pore properties of the materials. Moreover, from the water adsorption kinetics, it was observed that the rate constant of adsorption was varied at each relative pressure, which can be assumed that the water adsorption mechanism is diferent at each relative pressure. From these results, it was revealed that the prepared camphor leaf-based activated carbons have a promising ability to adsorb water vapor from humid air.
  • 19.

    Valuation of banana peel waste for producing activated carbon via NaOH and pyrolysis for methylene blue removal

    Maia Lana S. , Duizit Letícia D. , Pinhatio Fernanda R. and 1 other persons | 2021, 31(4) | pp.749~762 | number of Cited : 0
    Abstract
    The discharge of dye-containing industrial efuents such as methylene blue (MB) in water bodies has resulted in severe aquatic and human life problems. In addition to this factor, there is the accumulation of banana peel wastes, which can generate ecological damage. Thus, this research purpose a diferent method from the literature using the banana peel waste (BP) to produce activated carbon (ACBP) by NaOH activation followed by pyrolysis at 400 °C to remove methylene blue (MB). The material was characterized by TGA, XRD, SEM, BET, and FTIR. The infuence of dye concentration (10, 25, 50, 100, 250, and 500 mg L−1) was investigated. ACBP presented a well-developed pore structure with a predominance of mesopores and macropores. This morphological structure directly infuences the MB removal capacity. The highest efciency for dye removal was in the MB initial concentration of 25 mg L−1, sorbent of 0.03 g, and contact time of 60 min, which were 99.8%. The adsorption isotherms were well defned by Langmuir, Freundlich, and Temkin isotherm models. The Langmuir model represented the best ft of experimental data for ACBP with a maximum adsorption capacity of 232.5 mg g−1. This adsorbent showed a comparatively high performance to some previous works. So, the banana peel waste is an efcient resource for producing activated carbon and the adsorption of methylene blue.
  • 20.

    Growth of rGO nanostructures via facile wick and oil flame synthesis for environmental remediation

    Lekshmi G. S. , Tamilselvi R. , Prasad Karthika and 4 other persons | 2021, 31(4) | pp.763~777 | number of Cited : 0
    Abstract
    Oil spills into ocean or coastal waters can result in signifcant damage to the environment via pollution of aquatic ecosystems. Absorbents based on reduced graphene oxide (rGO) foams have the capacity to remove minor or major oil spills. However, conventional chemical synthesis of rGO often uses petrochemical precursors, potentially harmful chemicals, and requires special processing conditions that are expensive to maintain. In this work, an alternative cost-efective and environmentally friendly approach suitable for large-scale production of high-quality rGO directly from used cooking sunfower oil is discussed. Thus, produced faky graphene structures are efective in absorbing used commercial sunfower oil and engine oil, via monolayer physisorption in the case of used sunfower and engine oils facilitated by van der Waals forces, π–π stacking and hydrophobic interactions, π-cation (H+) stacking and radical scavenging activities. From adsorption kinetic models, frst-order kinetics provides a better ft for used sunfower oil adsorption (R2=0.9919) and second-order kinetics provides a better ft for engine oil adsorption (R2=0.9823). From intra-particle difusion model, R2 for USO is 0.9788 and EO is 0.9851, which indicates that both used sunfower and engine oils adsorption processes follow an intra-particle difusion mechanism. This study confrms that waste-derived rGO could be used for environmental remediation.
  • 21.

    Activated carbon microspheres derived from hydrothermally treated mango seed shells for acetone vapor removal

    de Andrade Robson C. , Menezes Rodrigo S. Gonzaga , Fiuza-Jr Raildo A. and 1 other persons | 2021, 31(4) | pp.779~793 | number of Cited : 0
    Abstract
    Mango fruit seed shells were used as starting materials to produce activated carbons for the capture of acetone, a typical volatile organic compound (VOC), from gaseous streams. This fruit waste presents high volatiles and low ashes contents, as expected for the lignocelulosic materials commonly used for the preparation of activated carbons. The starting material was hydrothermally treated at 180 or 250 °C for 5 h and the obtained hydrochars were activated with KOH solutions. The carbon samples were characterized by SEM, EDX, TG/DTA, Raman spectroscopy and textural analysis by physisorption. The adsorption capacity and adsorption cycles were investigated by TG. The hydrochars presented spherical morphology and the activated carbons derived from them presented heterogeneous micropore structures allowing to high capacity of acetone vapor removal, namely 472 mg/g, at 30 °C and 363 mg/g, at 50 °C. The results indicate that the adsorption capacity of the activated carbons is directly related to their Dubinin-Astakhov micropore surface areas and microporous volumes determined by NLDFT. The adsorption of acetone vapor showed a pseudo-frst order kinetics and both external and intraparticle transport contributed for the overall process. Highly efcient and stable acetone vapor removal was observed over the activated carbons after fve cycles.
  • 22.

    Modification of the graphene oxide surface with copper pentacyanonitrosylferrate nanoparticles for electro-oxidation of hydrazine

    Maraldi Vitor Alexandre , do Carmo Devaney Ribeiro | 2021, 31(4) | pp.795~807 | number of Cited : 0
    Abstract
    The preparation of graphene oxide and the modifcation of its surface directly with copper pentacyanonitrosylferrate (III) nanoparticles are presented in this work, as well as the characterization of the materials using Fourier-transform infrared spectra, X-ray difractometry and scanning electron microscopy techniques. Beyond that, the study on the electrochemical behavior of the dispersed bimetallic complex on the graphene oxide, as known as GOCuNP, surface was carried out by the cyclic voltammetry technique. The graphite paste electrode modifed with GOCuNP was successfully applied in the detection of hydrazine, presenting limit of detection of 1.58×10–6 mol L−1 at concentration range of 1.00×10–5 to 5.00×10–3 mol L−1 of hydrazine, being so the proposed bimetallic complex formed can be considered as a potential candidate for the manufacturing of electrochemical sensors for hydrazine detection.
  • 23.

    Facile tuning of carbon nanotube morphologies via residual carbon control during catalyst preparation stage

    Kim Sumin , Gang In Ji , Park Young Soo and 1 other persons | 2021, 31(4) | pp.809~819 | number of Cited : 0
    Abstract
    In this study, Fe–Mo–MgO catalysts for the synthesis of carbon nanotubes (CNTs) were prepared using the combustion method and CNTs were synthesized through catalytic chemical vapor deposition. The combustion time was controlled to 0.5, 1, 2, 3, 5, 10, and 24 h in the catalyst preparation stage. The residual carbon contents after the combustion stage and the morphologies of synthesized CNTs were also analyzed. The diameter, yield, and crystallinity of the synthesized CNTs were found to remarkably vary according to the combustion time in the catalyst preparation process. The amount of residual carbon in the catalyst considerably afects the purity, crystallinity, diameter and its distribution, and wall number of CNTs. Based on the yield and crystallinity, CNTs synthesized using the catalyst with a combustion time of 3 h were determined to be the most appropriate for application in feld emitters
  • 24.

    Development of nitrogen-doped carbon quantum dots as fluorescent probes for highly selective and sensitive detection of the heavy-ion Fe3+

    Liu Rui , Zhang Yan , Piao Yingai and 1 other persons | 2021, 31(4) | pp.821~829 | number of Cited : 0
    Abstract
    Highly luminescent carbon quantum dots (CQDs) are developed as fuorescent probes for selective detection of the heavy-ion Fe3+, where the CQDs exhibit excellent nontoxicity, functionalizability, sensitivity, and selectivity. Biomass-based CQDs and nitrogen-doped CQDs (N-CQDs) are synthesized for the selective detection of Fe3+ by using H2O2 as an oxidant and polyetherimide (PEI) as a nitrogen precursor by a green hydrothermal synthesis method. The prepared CQDs and N-CQDs exhibit an elliptical morphology and with an average particle size of 7 and 4 nm, respectively, and emit blue photoluminescence at 445 and 468 nm under excitation at 367 and 343 nm, respectively. The CQDs and N-CQDs exhibit good water solubility because of the abundant hydroxyl and carboxyl/carbonyl groups and graphic/pyrrolic/pyridinic nitrogen on the surfaces, giving rise to a quantum yield of about 24.2% and 30.7%, respectively. Notably, the Matrimony vine-PEI-based CQDs exhibit excellent Fe3+ selectivity and sensitivity relative to the Matrimony vine-based CQDs due to complexation of the numerous phenolic hydroxyl groups and nitrogen-containing groups with Fe3+, leading to increased fuorescence quenching, which greatly improves the sensitivity of detection. The minimum detection limit was 2.22 µmol L−1 with a complexation constant of 44.7.
  • 25.

    Synthesis of MoS2 nanoparticles grown on crumpled 3D graphene microballs using a microfluidic droplet generator

    Park Minsu , Kim Sanha , Jung Jae Hwan and 1 other persons | 2021, 31(4) | pp.831~836 | number of Cited : 0
    Abstract
    In this study, the MoS2 nanoparticles grown on crumpled 3D graphene microball (3D GM–MoS2) was synthesized using a microfuidic droplet generator with thermal evaporation-driven capillary compression and hydrothermal reaction. The morphology and size of 3D GM–MoS2 are controlled by the concentration of nano-sized graphene oxide (GO) and the fow rate of oil phase on the droplet generator. The 3D GM–MoS2 with fully sphere-shape and uniform size (~5 µm), and homogeneous growth of MoS2 nanoparticles could be synthesized at the fow rate of the oil phase of 60 µL/min with the optimized GO concentration of 1.0 mg/mL, and (NH4)2MoS4 concentration of 2.0 mg/mL.