In the new era of modern flexible and bendable technology, graphene-based materials have attracted great attention. The excellent electrical, mechanical, and optical properties of graphene as well as ...the ease of functionalization of its derivates have enabled graphene to become an attractive candidate for the construction of flexible devices. This paper provides a comprehensive review about the most recent progress in the synthesis and applications of graphene-based composites. Composite materials based on graphene, graphene oxide (GO), and reduced graphene oxide (rGO), as well as conducting polymers, metal matrices, carbon-carbon matrices, and natural fibers have potential application in energy-harvesting systems, clean-energy storage devices, and wearable and portable electronics owing to their superior mechanical strength, conductivity, and extraordinary thermal stability. Additionally, the difficulties and challenges in the current development of graphene are summarized and indicated. This review provides a comprehensive and useful database for further innovation of graphene-based composite materials.
Conducting polymers for battery applications have been subject to numerous investigations during the last two decades. However, the functional charging rates and the cycling stabilities have so far ...been found to be insufficient for practical applications. These shortcomings can, at least partially, be explained by the fact that thick layers of the conducting polymers have been used to obtain sufficient capacities of the batteries. In the present letter, we introduce a novel nanostructured high-surface area electrode material for energy storage applications composed of cellulose fibers of algal origin individually coated with a 50 nm thin layer of polypyrrole. Our results show the hitherto highest reported charge capacities and charging rates for an all polymer paper-based battery. The composite conductive paper material is shown to have a specific surface area of 80 m2 g−1 and batteries based on this material can be charged with currents as high as 600 mA cm−2 with only 6% loss in capacity over 100 subsequent charge and discharge cycles. The aqueous-based batteries, which are entirely based on cellulose and polypyrrole and exhibit charge capacities between 25 and 33 mAh g−1 or 38−50 mAh g−1 per weight of the active material, open up new possibilities for the production of environmentally friendly, cost efficient, up-scalable and lightweight energy storage systems.
Composites of polypyrrole (PPy) and Cladophora nanocellulose, reinforced with 8 μm‐thick chopped carbon filaments, can be used as electrode materials to obtain paper‐based energy‐storage devices with ...unprecedented performance at high charge and discharge rates. Charge capacities of more than 200 C g−1 (PPy) are obtained for paper‐based electrodes at potential scan rates as high as 500 mV s−1, whereas cell capacitances of ∼60–70 F g−1 (PPy) are reached for symmetric supercapacitor cells with capacitances up to 3.0 F (i.e.,0.48 F cm−2) when charged to 0.6 V using current densities as high as 31 A g−1 based on the PPy weight (i.e., 99 mA cm−2). Energy and power densities of 1.75 Wh kg−1 and 2.7 kW kg−1, respectively, are obtained when normalized with respect to twice the PPy weight of the smaller electrode. No loss in cell capacitance is seen during charging/discharging at 7.7 A g−1 (PPy) over 1500 cycles. It is proposed that the nonelectroactive carbon filaments decrease the contact resistances and the resistance of the reduced PPy composite. The present straightforward approach represents significant progress in the development of low‐cost and environmentally friendly paper‐based energy‐storage devices for high‐power applications.
Adding carbon filaments to composite electrodes containing polypyrrole and nanocellulose significantly improves the performance of supercapacitors based on these electrodes. The electrode charge capacity and cell capacitance are maintained at high potential scan rates and charging currents when carbon filaments are included to decrease the cell resistance. The results represent significant progress in the development of inexpensive, paper‐based, environmentally friendly energy‐storage devices.
Graphene oxide based electrode materials show remarkable electrochemical properties due to the improved specific surface area and electrical conductivity for supercapacitor applications. ...Hydrothermally synthesized graphene oxide based aluminum sulfide nanowalls on nickel foam (NF) have revealed excellent pseudocapacitive behavior with the specific capacitance 2362.15 F g-1 at 2 mVs-1 as observed through cyclic voltammetry. The galvanostatic charge-discharge measurements confirmed a specific capacitance 2373.51 F g-1 at 3 mAcm−2. Hexagonal phase of the graphene oxide (GO) based Al2S3 nanowalls also showed good discharge time of 820 s and energy density 118.68 WhKg−1 at 3 mAcm−2. Moreover, the fabricated electrode material exhibited good power density 2663.58 W kg-1 at 20 mAcm−2. The impedance results also confirmed the pseudocapacitive characteristics and revealed weak contact and Warburg resistances for the electrode material in half cell. Hence, GO based Al2S3 nanowalls performed as a prominent electrode material for asymmetric supercapacitors. Additionally, electrode material also exhibited excellent symmetric behavior, which again suggested a good electrode structure for supercapacitor applications.
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•GO based Al2S3 nanowalls showed excellent pseudo capacitance of 2362.15 F g-1.•GO based Al2S3 nanowalls revealed Pd of 2663.58 W kg-1 at current density 20 mAcm−2.•GO based Al2S3 nanowalls showed high Csp (2373.51 F g-1) and Ed (118.68 WhKg−1).•GO based Al2S3 nanowalls showed good symmetric behavior with Ed of 20.55 WhKg−1.•GO based Al2S3 nanowalls is suitable for symmetric and asymmetric supercapacitors.
A non-enzymatic dopamine electrochemical sensing probe was developed. A hexagonal shape zinc-doped cobalt oxide (Zn-Co
2
O
4
) nanostructure was prepared by a facile hydrothermal approach. The ...combination of Zn, which has an abundance of electrons, and Co
3
O
4
exhibited a synergistically electron-rich nanocomposite. The crystallinity of the nanostructure was investigated using X-ray diffraction. A scanning electron microscope (SEM) was used to examine the surface morphology, revealing hexagonal nanoparticles with an average particle size of 400 nm. High-resolution transmission electron microscopy (HR-TEM) was used to confirm the nanostructure of the doped material. The nanostructure’s bonding and functional groups were verified using Fourier transform infrared spectroscopy (FTIR). The electrochemical characterization was conducted by using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and amperometry. The resistivity of the electrode was confirmed through EIS and showed that the bare glassy carbon electrode (GCE) exhibited higher charge transfer resistance as compared to modified Zn-Co
2
O
4
/GCE. The sensing probe was developed by modifying the surface of GCE with Zn-Co
2
O
4
nanostructure and tested as an electrochemical sensor for dopamine oxidation; it operated best at a working potential of 0.17 V (vs Ag/AgCl). The developed sensor exhibited a low limit of detection (0.002 µM), a high sensitivity (126 µA. µM
−1
cm
−2
), and a wide linear range (0.2 to 185 µM). The sensor showed a short response time of < 1 s. The sensor’s selectivity was investigated in the presence of coexisting species (uric acid, ascorbic acid, adrenaline, epinephrine, norepinephrine, histamine, serotonin, tyramine, phenethylamine, and glucose) with no effects on dopamine determination results. The developed sensor was also successfully used for determining dopamine concentrations in a real sample.
Graphical abstract
The exploration of electrode functional materials for supercapacitors may bring a revolution to energy storage devices to boost the portable industry. Herein, lanthanum sulfide nanorods and reduced ...graphene oxide (rGO)–templated lanthanum sulfide nanorods have been synthesized using the hydrothermal process. Structural, morphological, and compositional analyses were conducted using X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The specific surface area has been measured using the Brunauer–Emmett–Teller technique. Individual lanthanum sulfide and rGO-templated lanthanum sulfide showed the morphology of nanorods. Cyclic voltammetry tests predicted the pseudocapacitive nature of the lanthanum sulfides for supercapacitor applications. The rGO effectively improved the electrochemical characteristics of the lanthanum sulfide, which might be due to the facilitation of charge carriers through nanorods, as the rGO-templated lanthanum sulfide nanorod showed a specific capacitance of 75.17 F/g at a scan rate of 30 mV/s evidenced by cyclic voltammetry (CV) curves. The rGO significantly increased the discharge time from 60 to 188 s, specific capacitance from 20.32 to 34.12 F/g, and energy density from 572 to 1185 mW/kg compared to individual lanthanum sulfide nanorods as seen by the galvanostatic charge/discharge profile. The rGO-templated lanthanum sulfide nanorods showed a power density of 255.20 W/kg at a high current density of 0.2 A/g and a specific capacitance retention up to 91.60% for 2000 cycles at scan rate of 20 mV/s. Symmetric cell exhibited the specific capacitance of 94.45 F/g, energy density of 6.43 Wh/kg at the current density of 0.05 A/g, and power density of 351.25 W/kg at the current density of 0.2 A/g. The test results indicate that the use of rGO is effective in improving the electrochemical characteristics of lanthanum sulfide nanorods for supercapacitor applications.
In recent era of modern and bendable technology, energy dearth arises as a paramount subject around the globe with a dire demand of flexible and lightweight energy storage devices. This study targets ...fabrication of reduced graphene oxide (rGO) and utility of abundantly available, cost effective, and environment friendly lignocelluloses (LC) fibers extracted from Carica papaya source, as a binder to bind active material (rGO) as robust and compact paper sheet. Fabricated samples were analyzed by X-ray diffraction for crystallographic analysis, Scanning electron microscopy, Transmission electron microscope for morphology, Fourier transform infrared spectroscopy for structural bonding, and Raman spectroscopy for vibrational modes. Robust and bendable rGO/LC paper electrode was tested for energy storage application by employing in different characterizations, i.e., cyclic voltammetry for capacitive behavior, galvanostatic charge–discharge for symmetric EDLC, and electrochemical impedance spectroscopy for resistive charge kinetics, respectively. rGO/LC composite sheet employed as working electrode in 3-electrode CV measurements and revealed specific capacitance of 591 F/g at a scan rate of 5 mV/s by keeping the undistorted shape of voltammograms at higher scan rates which present it as a suitable candidate for modern flexible and energy storage devices. rGO/LC-based symmetric cell revealed the highest specific capacitance of 228 F/g at applied current density of 0.1 A/g, the energy density of 6.3 Wh/kg, and power density of 129 W/kg, respectively. rGO/LC-based symmetric cell confirmed the cycling stability by revealing capacitance retention of 82% after 200 cycles. It can conclude that biomass-based rGO paper sheet can be a potential candidate as environmentally safe with remarkable electrochemical activity in energy storage applications.
Composite materials and their applications constitute a hot field of research nowadays due to the fact that they comprise a combination of the unique properties of each component of which they ...consist. Very often, they exhibit better performance and properties compared to their combined building blocks. Graphene oxide (GO), as the most widely used derivative of graphene, has attracted widespread attention because of its excellent properties. Abundant oxygen-containing functional groups on GO can provide various reactive sites for chemical modification or functionalization of GO, which in turn can be used to develop novel GO-based composites. This review outlines the most recent advances in the field of novel dyes and pigments encompassing GO as a key ingredient or as an important cofactor. The interactions of graphene with other materials/compounds are highlighted. The special structure and unique properties of GO have a great effect on the performance of fabricated hybrid dyes and pigments by enhancing the color performance of dyes, the anticorrosion properties of pigments, the viscosity and rheology of inks, etc., which further expands the applications of dyes and pigments in dyeing, optical elements, solar-thermal energy storage, sensing, coatings, and microelectronics devices. Finally, challenges in the current development as well as the future prospects of GO-based dyes and pigments are also discussed. This review provides a reference for the further exploration of novel dyes and pigments.
Highly porous polypyrrole (PPy)-nanocellulose paper sheets have been evaluated as inexpensive and disposable electrochemically controlled three-dimensional solid phase extraction materials. The ...composites, which had a total anion exchange capacity of about 1.1 mol kg(-1), were used for extraction and subsequent release of negatively charged fluorophore tagged DNA oligomers via galvanostatic oxidation and reduction of a 30-50 nm conformal PPy layer on the cellulose substrate. The ion exchange capacity, which was, at least, two orders of magnitude higher than those previously reached in electrochemically controlled extraction, originated from the high surface area (i.e. 80 m(2) g(-1)) of the porous composites and the thin PPy layer which ensured excellent access to the ion exchange material. This enabled the extractions to be carried out faster and with better control of the PPy charge than with previously employed approaches. Experiments in equimolar mixtures of (dT)(6), (dT)(20), and (dT)(40) DNA oligomers showed that all oligomers could be extracted, and that the smallest oligomer was preferentially released with an efficiency of up to 40% during the reduction of the PPy layer. These results indicate that the present material is very promising for the development of inexpensive and efficient electrochemically controlled ion-exchange membranes for batch-wise extraction of biomolecules.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The past one and a half decades have witnessed the tremendous progress of two-dimensional (2D) crystals, including graphene, transition-metal dichalcogenides, black phosphorus, MXenes, hexagonal ...boron nitride, etc., in a variety of fields. The key to their success is their unique structural, electrical, mechanical and optical properties. Herein, this paper gives a comprehensive summary on the recent advances in 2D materials for optoelectronic approaches with the emphasis on the morphology and structure, optical properties, synthesis methods, as well as detailed optoelectronic applications. Additionally, the challenges and perspectives in the current development of 2D materials are also summarized and indicated. Therefore, this review can provide a reference for further explorations and innovations of 2D material-based optoelectronics devices.
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