scholarly journals Effects of Ionic Liquid and Biomass Sources on Carbon Nanotube Physical and Electrochemical Properties

2021 ◽  
Vol 13 (5) ◽  
pp. 2977
Author(s):  
Kudzai Mugadza ◽  
Annegret Stark ◽  
Patrick G. Ndungu ◽  
Vincent O. Nyamori
Keyword(s):  
Ionic Liquid ◽  
Electrochemical Properties ◽  
Photoelectron Spectroscopy ◽  
Nitrogen Doping ◽  
Electrochemical Impedance ◽  
Low Cost ◽  
Doping Content ◽  
Ongoing Research ◽  
Surface Areas ◽  
Pyridinic Nitrogen

The ongoing research toward meeting global energy demands requires novel materials from abundant renewable resources. This work involves an investigation on nitrogen-doped carbon nanotubes (N-CNTs) synthesized from relatively low-cost and readily available biomass as carbon precursors and their use as electrodes for supercapacitors. The influence of the ionic liquid 1-butyl-3-methylimidazolium chloride, or its combination with either sugarcane bagasse or cellulose (IL-CNTs, ILBag-CNTs, and ILCel-CNTs, respectively), in the synthesis of N-CNTs and the resultant effect on their physical and electrochemical properties was studied. Systematic characterizations of the N-CNTs employing transmission electron microscopy (TEM), thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), elemental analysis, nitrogen sorption analysis, cyclic voltammetry, and electrochemical impedance spectroscopy were performed. TEM data analysis showed that the mean outer diameters decreased, in the order of IL-CNTs > ILBag-CNTs > ILCel-CNTs. The N-CNTs possess only pyridinic and pyrrolic nitrogen-doping moieties. The pyridinic nitrogen-doping content is lowest in IL-CNTs and highest in ILCel-CNTs. The N-CNTs are mesoporous with surface areas in the range of 21–52 m2 g−1. The ILCel-CNTs had the highest specific capacitance of 30 F g−1, while IL-CNTs has the least, 10 F g−1. The source of biomass is beneficial for tuning physicochemical properties such as the size and surface areas of N-CNTs, the pyridinic nitrogen-doping content, and ultimately capacitance, leading to materials with excellent properties for electrochemical applications.

scholarly journals A Facile and Green Synthesis of a MoO2-Reduced Graphene Oxide Aerogel for Energy Storage Devices

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 594 ◽  
Author(s):  
Mara Serrapede ◽  
Marco Fontana ◽  
Arnaud Gigot ◽  
Marco Armandi ◽  
Glenda Biasotto ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Chemical Reduction ◽  
Low Cost ◽  
Xps Analysis ◽  
3D Scaffold ◽  
Energy Storage Devices ◽  
Reduced Graphene

A simple, low cost, and “green” method of hydrothermal synthesis, based on the addition of l-ascorbic acid (l-AA) as a reducing agent, is presented in order to obtain reduced graphene oxide (rGO) and hybrid rGO-MoO2 aerogels for the fabrication of supercapacitors. The resulting high degree of chemical reduction of graphene oxide (GO), confirmed by X-Ray Photoelectron Spectroscopy (XPS) analysis, is shown to produce a better electrical double layer (EDL) capacitance, as shown by cyclic voltammetric (CV) measurements. Moreover, a good reduction yield of the carbonaceous 3D-scaffold seems to be achievable even when the precursor of molybdenum oxide is added to the pristine slurry in order to get the hybrid rGO-MoO2 compound. The pseudocapacitance contribution from the resulting embedded MoO2 microstructures, was then studied by means of CV and electrochemical impedance spectroscopy (EIS). The oxidation state of the molybdenum in the MoO2 particles embedded in the rGO aerogel was deeply studied by means of XPS analysis and valuable information on the electrochemical behavior, according to the involved redox reactions, was obtained. Finally, the increased stability of the aerogels prepared with l-AA, after charge-discharge cycling, was demonstrated and confirmed by means of Field Emission Scanning Electron Microscopy (FESEM) characterization.

scholarly journals Diazonium-Modified Screen-Printed Electrodes for Immunosensing Growth Hormone in Blood Samples

Biosensors ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 88 ◽  
Author(s):  
Nan Li ◽  
Ari M. Chow ◽  
Hashwin V. S. Ganesh ◽  
Melanie Ratnam ◽  
Ian R. Brown ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Low Cost ◽  
High Sensitivity ◽  
Sample Volume ◽  
Screening Methods ◽  
Serum Samples ◽  
Potential Applicability ◽  
Screen Printed

Altered growth hormone (GH) levels represent a major global health challenge that would benefit from advances in screening methods that are rapid and low cost. Here, we present a miniaturized immunosensor using disposable screen-printed carbon electrodes (SPCEs) for the detection of GH with high sensitivity. The diazonium-based linker layer was electrochemically deposited onto SPCE surfaces, and subsequently activated using covalent agents to immobilize monoclonal anti-GH antibodies as the sensing layer. The surface modifications were monitored using contact angle measurements and X-ray photoelectron spectroscopy (XPS). The dissociation constant, Kd, of the anti-GH antibodies was also determined as 1.44 (±0.15) using surface plasmon resonance (SPR). The immunosensor was able to detect GH in the picomolar range using a 20 µL sample volume in connection with electrochemical impedance spectroscopy (EIS). The selectivity of the SPCE-based immunosensors was also challenged with whole blood and serum samples collected at various development stages of rats, demonstrating the potential applicability for detection in biological samples. Our results demonstrated that SPCEs provided the development of low-cost and single-use electrochemical immunosensors in comparison with glassy carbon electrode (GCE)-based ones.

scholarly journals Effects of the Carbon Support Doping with Nitrogen for the Hydrogen Production from Formic Acid over Ni Catalysts

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4111 ◽  
Author(s):  
Alina D. Nishchakova ◽  
Dmitri A. Bulushev ◽  
Olga A. Stonkus ◽  
Igor P. Asanov ◽  
Arcady V. Ishchenko ◽  
...  
Keyword(s):  
Formic Acid ◽  
Photoelectron Spectroscopy ◽  
Total Content ◽  
Carbon Support ◽  
Nickel Catalysts ◽  
Synthesis Temperature ◽  
Free Carbon ◽  
Nitrogen Doped ◽  
Surface Areas ◽  
Pyridinic Nitrogen

Porous nitrogen-doped and nitrogen-free carbon materials possessing high specific surface areas (400–1000 m2 g−1) were used for deposition of Ni by impregnation with nickel acetate followed by reduction. The nitrogen-doped materials synthesized by decomposition of acetonitrile at 973, 1073, and 1173 K did not differ much in the total content of incorporated nitrogen (4–5 at%), but differed in the ratio of the chemical forms of nitrogen. An X-ray photoelectron spectroscopy study showed that the rise in the synthesis temperature led to a strong growth of the content of graphitic nitrogen on the support accompanied by a reduction of the content of pyrrolic nitrogen. The content of pyridinic nitrogen did not change significantly. The prepared nickel catalysts supported on nitrogen-doped carbons showed by a factor of up to two higher conversion of formic acid as compared to that of the nickel catalyst supported on the nitrogen-free carbon. This was related to stabilization of Ni in the state of single Ni2+ cations or a few atoms clusters by the pyridinic nitrogen sites. The nitrogen-doped nickel catalysts possessed a high stability in the reaction at least within 5 h and a high selectivity to hydrogen (97%).

scholarly journals Characterization of ultraviolet-modified biochar from different feedstocks for enhanced removal of hexavalent chromium from water

2019 ◽  
Vol 79 (9) ◽  
pp. 1705-1716 ◽  
Author(s):  
Zhongya Peng ◽  
Xiaomei Liu ◽  
Hongkun Chen ◽  
Qinglong Liu ◽  
Jingchun Tang
Keyword(s):  
Functional Groups ◽  
Hexavalent Chromium ◽  
Uv Irradiation ◽  
Photoelectron Spectroscopy ◽  
Environmental Remediation ◽  
Low Cost ◽  
Surface Areas ◽  
Modified Biochar ◽  
Sorption Ability ◽  
Novel Material

Abstract Biochars produced from different feedstocks via pyrolytic carbonization and ultraviolet (UV) modification were used as alternative adsorbents for aqueous hexavalent chromium (Cr(VI)) remediation. Structural and morphological analysis showed that UV irradiation increased the surface area of biochar and added a large amount of oxygen-containing functional groups on the biochar's surface, resulting in about 2–5 times increase of Cr(VI) removing capacity (14.39–20.04 mg/g) compared to that of unmodified biochars (3.60–8.43 mg/g). The sorption ability among different feedstocks after modification was as follows: corn stack > sawdust > wheat straw. The adsorption kinetics and adsorption isotherm data agreed well with the pseudo-second-order model and Freundlich model, respectively. Experimental and modeling results suggested that the oxygen-containing functional groups and surface areas of biochars were notably increased after UV irradiation, which was mainly governed by surface complexation. X-ray photoelectron spectroscopy analysis showed that reduction occurred during Cr(VI) adsorption. In addition, UV irradiation significantly increased the concentration of dissolved organic matter (DOM) in biochars. The collected outcomes showed that UV-modified biochar was a good material for the removal of hexavalent chromium from aqueous medium. The excellent adsorption capacity, environmental-friendly and low cost properties made the novel material an auspicious candidate for environmental remediation.

scholarly journals Nitrogen-Doped Carbon Aerogels Derived from Starch Biomass with Improved Electrochemical Properties for Li-Ion Batteries

2021 ◽  
Vol 22 (18) ◽  
pp. 9918
Author(s):  
Marcelina Kubicka ◽  
Monika Bakierska ◽  
Krystian Chudzik ◽  
Michał Świętosławski ◽  
Marcin Molenda
Keyword(s):  
Electrochemical Properties ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Potato Starch ◽  
Specific Capacity ◽  
Carbon Aerogel ◽  
Carbon Aerogels ◽  
Modern World ◽  
X Ray ◽  
Li Ion

Among all advanced anode materials, graphite is regarded as leading and still-unrivaled. However, in the modern world, graphite-based anodes cannot fully satisfy the customers because of its insufficient value of specific capacity. Other limitations are being nonrenewable, restricted natural graphite resources, or harsh conditions required for artificial graphite production. All things considered, many efforts have been made in the investigation of novel carbonaceous materials with desired properties produced from natural, renewable resources via facile, low-cost, and environmentally friendly methods. In this work, we obtained N-doped, starch-based carbon aerogels using melamine and N2 pyrolysis as the source of nitrogen. The materials were characterized by X-ray powder diffraction, elemental analysis, X-ray photoelectron spectroscopy, galvanostatic charge–discharge tests, cyclic voltammetry, and electrochemical impedance spectroscopy. Depending on the doping method and the nitrogen amount, synthesized samples achieved different electrochemical behavior. N-doped, bioderived carbons exhibit far better electrochemical properties in comparison with pristine ones. Materials with the optimal amount of nitrogen (such as MCAGPS-N8.0%—carbon aerogel made from potato starch modified with melamine and CAGPS-N1.2%—carbon aerogel made from potato starch modified by N2 pyrolysis) are also competitive to graphite, especially for high-performance battery applications. N-doping can enhance the efficiency of Li-ion cells mostly by inducing more defects in the carbon matrix, improving the binding ability of Li+ and charge-transfer process.

Voltammetric determination of hexestrol based on the enhanced effect of a polymerized 3-decyl-1-(3-pyrrole-propyl)imidazolium tetrafluoroborate ionic liquid film electrode

2016 ◽  
Vol 94 (5) ◽  
pp. 470-475 ◽  
Author(s):  
Yingying Wu ◽  
Xuemin Chen ◽  
Yanying Wang ◽  
Chunya Li
Keyword(s):  
Ionic Liquid ◽  
Liquid Film ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Carbon Electrode ◽  
Film Electrode ◽  
Oxidation Peak ◽  
Polymerized Ionic Liquid

3-Decyl-1-(3-pyrrole-propyl)imidazolium tetrafluoroborate (DPIMBF4) ionic liquid was synthesized and characterized. DPIMBF4 ionic liquid not only possesses a pyrrole group that can be electrochemically polymerized onto a glassy carbon electrode surface by using a multipotential step technique, but it also contains a long carbon chain that can improve the stability of a polymerized ionic liquid film in an aqueous solution. X-ray photoelectron spectroscopy, scanning electron microscope, and electrochemical impedance spectroscopy were used to confirm the successful polymerization of the ionic liquid. Voltammetry was employed to investigate the electrochemical behaviors of an environmental estrogen, hexestrol, at the polymerized ionic liquid film electrode. Hexestrol presents an irreversible oxidation peak at the polymerized DPIMBF4 ionic liquid film electrode. Compared with the bare glassy carbon electrode, the oxidation peak of hexestrol increased significantly on the polymerized DPIMBF4 ionic liquid film electrode. The oxidation peak current was found to be linearly related to hexestrol concentration in the range of 5.0 × 10−9 to 1.0 × 10−5 mol L−1. The detection limit was calculated to be 1.25 × 10−9 mol L−1 (S/N = 3). Hexestrol in crucian meat was determined using the polymerized DPIMBF4 ionic liquid film electrode with good accuracy.

scholarly journals A low-cost, low-density, and corrosion resistant AlFeMnSi compositionally complex alloy

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
S. P. O’Brien ◽  
J. Christudasjustus ◽  
L. Esteves ◽  
S. Vijayan ◽  
J. R. Jinschek ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Surface Film ◽  
Low Cost ◽  
Incongruent Dissolution ◽  
Complex Alloy ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractA compositionally complex alloy was designed, consisting of equiatomic concentrations of four low-cost commodity elements (Al, Fe, Mn, and Si). The alloy was characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The corrosion of the AlFeMnSi alloy, as evaluated using potentiodynamic polarization tests and electrochemical impedance spectroscopy in 0.6 M NaCl solution, was comparable with that of stainless steel (SS) 304L. Detailed X-ray photoelectron spectroscopy analysis was carried out, including the determination of high-resolution spectra and surface sputtering. In addition, scanning transmission electron microscopy was also used to study the surface film(s) developed after constant immersion. The AlFeMnSi alloy exhibited a unique form of ‘passivity’ that arises from the development of a silicon-rich surface film from dynamic incongruent dissolution.

scholarly journals A low-cost, low-density and corrosion resistant compositionally complex alloy: AlFeMnSi

2020 ◽  
Author(s):  
Sean O'Brien ◽  
Luiza Esteves ◽  
Nick Birbilis ◽  
Rajeev Gupta
Keyword(s):  
Photoelectron Spectroscopy ◽  
Lower Cost ◽  
Electrochemical Impedance ◽  
Surface Film ◽  
Low Cost ◽  
Complex Alloy ◽  
Corrosion Resistant ◽  
X Ray ◽  
New Class ◽  
Promising Alloy

A new class of compositionally complex alloy, consisting of equiatomic concentrations of Al, Fe, Mn and Si is reported. The alloy was characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Corrosion behavior of the AlFeMnSi alloy, as evaluated using potentiodynamic polarization tests and electrochemical impedance spectroscopy in 0.6 M NaCl solution, was comparable with that of stainless steel (SS) 304L. X-ray photoelectron spectroscopy was used to study the AlFeMnSi surface film. The AlFeMnSi alloy also exhibited a lower cost, lower density, and a higher hardness as compared with SS 304L, rendering it a promising alloy for bespoke applications.

scholarly journals Graphene Oxide Nanoparticles Modified Paper Electrode as a Biosensing Platform for Detection of the htrA Gene of O. tsutsugamushi

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4366
Author(s):  
Deepak Kala ◽  
Tarun Kumar Sharma ◽  
Shagun Gupta ◽  
Vivek Verma ◽  
Atul Thakur ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Electrochemical Properties ◽  
Differential Pulse Voltammetry ◽  
Electrochemical Impedance ◽  
Low Cost ◽  
Differential Pulse ◽  
Oxide Nanoparticles ◽  
Layer By Layer ◽  
Dna Sensor ◽  
Pulse Voltammetry

The unique structural and electrochemical properties of graphene oxide (GO) make it an ideal material for the fabrication of biosensing devices. Therefore, in the present study, graphene oxide nanoparticles modified paper electrodes were used as a low-cost matrix for the development of an amperometric DNA sensor. The graphene oxide was synthesized using the modified hummers method and drop cast on a screen-printed paper electrode (SPPE) to enhance its electrochemical properties. Further, the GO/SPPE electrode was modified with a 5′NH2 labeled ssDNA probe specific to the htrA gene of Orientia tsutsugamushi using carbodiimide cross-linking chemistry. The synthesized GO was characterized using UV-Vis, FTIR, and XRD. The layer-by-layer modification of the paper electrode was monitored via FE-SEM, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The sensor response after hybridization with single-stranded genomic DNA (ssGDNA) of O. tsutsugamushi was recorded using differential pulse voltammetry (DPV). Methylene blue (1 mM in PBS buffer, pH 7.2) was used as a hybridization indicator and [Fe(CN)6]−3/−4 (2.5 mM in PBS buffer, pH 7.2) as a redox probe during electrochemical measurements. The developed DNA sensor shows excellent sensitivity (1228.4 µA/cm2/ng) and LOD (20 pg/µL) for detection of O. tsutsugamushi GDNA using differential pulse voltammetry (DPV).

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