| 1. |
- Dyatkin, Boris, et al.
(författare)
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Electrode Surface Composition of Dual-Intercalation, All-Graphite Batteries
- 2017
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Ingår i: C-JOURNAL OF CARBON RESEARCH. - : MDPI. - 2311-5629. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Dual-intercalation batteries implement graphite electrodes as both cathodes and anodes and offer high specific energy, inexpensive and environmentally sustainable materials, and high operating voltages. Our research investigated the influence of surface composition on capacities and cycling efficiencies of chemically functionalized all-graphite battery electrodes. We subjected core-shell spherical particles and synthetic graphite flakes to high-temperature air oxidation, and hydrogenation to introduce, respectively, -OH, and -H surface functional groups. We identified noticeable influences of electrode surface chemistry on first-cycle efficiencies and charge storage densities of anion and cation intercalation into graphite electrodes. We matched oxidized cathodes and hydrogenated anodes in dual-ion batteries and improved their overall performance. Our approach provides novel fundamental insight into the anion intercalation process and suggests inexpensive and environmentally sustainable methods to improve performance of these grid-scale energy storage systems.
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| 2. |
- Hedayati, Ali, 1984, et al.
(författare)
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Chemical Recycling of Consumer-Grade Black Plastic into Electrically Conductive Carbon Nanotubes
- 2019
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Ingår i: C - Journal of Carbon Research. - : MDPI AG. - 2311-5629. ; 5:2
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Tidskriftsartikel (refereegranskat)abstract
- The global plastics crisis has recently focused scientists' attention on finding technical solutions for the ever-increasing oversupply of plastic waste. Black plastic is one of the greatest contributors to landfill waste, because it cannot be sorted using industrial practices based on optical reflection. However, it can be readily upcycled into carbon nanotubes (CNTs) using a novel liquid injection reactor (LIR) chemical vapor deposition (CVD) method. In this work, CNTs were formed using black and white polystyrene plastics to demonstrate that off-the-shelf materials can be used as feedstock for growth of CNTs. Scanning electron microscopy analysis suggests the CNTs from plastic sources improve diameter distribution homogeneity, with slightly increased diameters compared with control samples. Slight improvements in quality, as determined by Raman spectroscopy of the D and G peaks, suggest that plastics could lead to increased quality of CNTs. A small device was constructed as a demonstrator model to increase impact and public engagement.
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| 3. |
- Larsson, Karin, 1955-
(författare)
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The Combined Influence of Dopant Species and Surface Termination on the Electronic Properties of Diamond Surfaces
- 2020
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Ingår i: C-JOURNAL OF CARBON RESEARCH. - : MDPI AG. - 2311-5629. ; 6:2
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Forskningsöversikt (refereegranskat)abstract
- The combined effects of geometrical structure and chemical composition on the diamond surface electronic structures have been investigated in the present study by using high-level theoretical calculations. The effects of diamond surface planes [(111) vs. (100)], surface terminations (H, F, OH, O-ontop, O-bridge, vs. NH2), and substitutional doping (B, N vs. P), were of the largest interest to study. As a measure of different electronic structures, the bandgaps, work functions, and electron affinities have been used. In addition to the effects by the doping elements, the different diamond surface planes [(111) vs. (100)] were also observed to cause large differences in the electronic structures. With few exceptions, this was also the case for the surface termination species. For example, O-ontop-termination was found to induce surface electron conductivities for all systems in the present study (except for a non-doped (100) surface). The other types of surface terminating species induced a reduction in bandgap values. The calculated bandgap ranges for the (111) surface were 3.4-5.7 (non-doping), and 0.9-5.3 (B-doping). For the (100) surface, the ranges were 0.9-5.3 (undoping) and 3.2-4.3 (B-doping). For almost all systems in the present investigation, it was found that photo-induced electron emission cannot take place. The only exception is the non-doped NH2-terminated diamond (111) surface, for which a direct photo-induced electron emission is possible.
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| 4. |
- Ossler, Frederik, et al.
(författare)
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Finger-like carbon-based nanostructures produced by combustion of flour-based sticks (spaghetti)
- 2019
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Ingår i: C: Journal of Carbon Research. - : MDPI AG. - 2311-5629.
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Tidskriftsartikel (refereegranskat)abstract
- Biomass is becoming particularly important as a starting material for advanced carbon structures. In this study, we found interesting nanostructures on the surface of burnt spaghetti using scanning electron microscopy, transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX) for analysis. The structures were elongated and finger-like, with evidence that the tubes have shell and core components. The shell was carbon that included amorphous and layered graphene structures. EDX showed enriched potassium and phosphorous in the core and at the tip of the tubes. The results indicate that tube formation depends on phase separation of polar/ionic and nonpolar moieties when water is produced in the biomass from the pyrolysis/combustion. The tube growth is most probably due to the raising pressure of vapor that cannot escape through the carbon film that is formed at the surface of the stick from flame heat. This process resembles glass blowing or volcanic activity, where the carbon acts as the glass or earth’s crust, respectively. These observations suggest that new interesting tubular nanostructures with different properties on the inside and outside can be produced in a relatively simple way, utilizing processes of combustion of starch-rich biomass materials.
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| 5. |
- Shtepliuk, Ivan, et al.
(författare)
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Insights into the Electrochemical Behavior of Mercury on Graphene/SiC Electrodes
- 2019
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Ingår i: C — Journal of Carbon Research. - : MDPI. - 2311-5629. ; 5:3
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Tidskriftsartikel (refereegranskat)abstract
- Fast and real time detection of Mercury (Hg) in aqueous solutions is a great challenge due to its bio-accumulative character and the detrimental effect on human health of this toxic element. Therefore, development of reliable sensing platforms is highly desirable. Current research is aiming at deep understanding of the electrochemical response of epitaxial graphene to Mercury exposure. By performing cyclic voltammetry and chronoamperometry measurements as well as density functional theory calculations, we elucidate the nature of Hg-involved oxidation-reduction reactions at the graphene electrode and shed light on the early stages of Hg electrodeposition. The obtained critical information of Hg behavior will be helpful for the design and processing of novel graphene-based sensors.
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| 6. |
- Le, Thi Kim Cuong, et al.
(författare)
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Observation of Structural Changes during Oxidation of Black and Brown Soot Using Raman Spectroscopy
- 2024
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Ingår i: C: Journal of Carbon Research. - 2311-5629. ; 10:38
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Tidskriftsartikel (refereegranskat)abstract
- In this study, Raman spectroscopy has been used to evaluate the evolution of the structural modification of soot during oxidation processes at various preset temperatures up to 700 °C. Two types of well-characterized mini-CAST soot, representing black soot and brown soot, were examined. The major difference between the signals from the two types of soot was the higher photoluminescence (PL) signal for brown soot compared with black soot, in addition to some variations in the first-order Raman signatures such as oxygenated groups and their evolutions during thermal oxidation treatment. An interesting observation was the increase in the PL signal for brown soot at increasing temperatures up to 150 °C probably due to the formation of small oxidized polycyclic aromatic hydrocarbon and defects, followed by a decrease in the PL signal until the soot was fully oxidized. We also demonstrated that brown soot is prone to oxidation in ex situ measurements, a factor that should be considered in the Raman analysis of soot.
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| 7. |
- Menzler, M., et al.
(författare)
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Testing of Diamond Electrodes as Biosensor for Antibody-Based Detection of Immunoglobulin Protein with Electrochemical Impedance Spectroscopy
- 2022
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Ingår i: C-Journal of Carbon Research. - : MDPI AG. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- To control the increasing virus pandemics, virus detection methods are essential. Today's standard virus detections methods are fast (immune assays) or precise (PCR). A method that is both fast and precise would enable more efficient mitigation measures and better life comfort. According to recent papers, electrochemical impedance spectroscopy (EIS) has proven to detect viruses fast and precise. Boron-doped diamond (BDD) was used as a high-performance electrode material in these works. The aim of this work was to perform an initial test of BDD-based EIS for biosensing. As an easily available standard biomaterial, human immunoglobulin G (IgG) was used as analyte. Niobium plates were coated via hot-filament activated chemical vapor deposition with polycrystalline diamond, and doped with boron for electrical conductivity. An anti-human IgG antibody was immobilised on the BDD electrodes as a biosensing component. Four different analyte concentrations up to 1.1 mu g per litre were tested. During EIS measurements, both impedance over frequency curves and Nyquist plot demonstrated no clear sign of a change of the charge transfer resistance. Thus, no positive statement about a successful biosensing could be made so far. It is assumed that these issues need to be investigated and improved, including the relation of BDD electrode size to electrolyte volume, termination of the BDD electrodes (H, O) for a successful functionalisation and EIS frequency range. The work will be continued concerning these improvement issues in order to finally use virus materials as analyte.
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| 8. |
- Ritopečki, Milica S., et al.
(författare)
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Density Functional Theory Analysis of the Impact of Boron Concentration and Surface Oxidation in Boron-Doped Graphene for Sodium and Aluminum Storage
- 2023
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Ingår i: C - Journal of Carbon Research. - : MDPI. - 2311-5629. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Graphene is thought to be a promising material for many applications. However, pristine graphene is not suitable for most electrochemical devices, where defect engineering is crucial for its performance. We demonstrate how the boron doping of graphene can alter its reactivity, electrical conductivity and potential application for sodium and aluminum storage, with an emphasis on novel metal-ion batteries. Using Density Functional Theory calculations, we investigate both the influence of boron concentration and the oxidation of the material on the mentioned properties. It is demonstrated that the presence of boron in graphene increases its reactivity towards atomic hydrogen and oxygen-containing species; in other words, it makes B-doped graphene more prone to oxidation. Additionally, the presence of these surface functional groups significantly alters the type and strength of the interaction of Na and Al with the given materials. Boron-doping and the oxidation of graphene is found to increase the Na storage capacity of graphene by a factor of up to four, and the calculated sodiation potentials indicate the possibility of using these materials as electrode materials in high-voltage Na-ion batteries.
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| 9. |
- Simões Dos Reis, Glaydson
(författare)
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Sustainable supercapacitors based on polypyrrole-doped activated biochar from wood waste electrodes
- 2023
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Ingår i: C - Journal of Carbon Research. - 2311-5629. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis of high-performance carbon-based materials from biomass residues for electrodes has been considered a challenge to achieve in supercapacitor-based production. In this work, activated biochar has been prepared as the active electrode material for supercapacitors (SCs), and an effective method has been explored to boost its capacitive performance by employing polypyrrole (PPy) as a biochar dopant. The results for physicochemical characterization data have demonstrated that PPy doping affects the biochar morphology, specific surface area, pore structure, and incorporation of surface functionalities on modified biochar. Biochar-PPy exhibited a surface area of 87 m2 g−1, while pristine biochar exhibited 1052 m2 g−1. The SCs were assembled employing two electrodes sandwiched with PVA solid-state film electrolyte as a separator. The device was characterized by standard electrochemical assays that indicated an improvement of 34% in areal capacitance. The wood electrodes delivered high areal capacitances of 282 and 370 mF cm−2 at 5 mA cm−2, for pure biochar and biochar doped with PPy, respectively, with typical retention in the capacitive response of 72% at the end of 1000 cycles of operation of the supercapacitor at high current density, indicating that biochar-PPy-based electrode devices exhibited a higher energy density when compared to pure biochar devices.
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