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Specific capacitance plot against the current density (a) cyclic stability of both symmetric devices at 3 A g À1 (b) first four charge/ discharge curves of the Fe 2 O 3 /GA SC at 2.5 A g À1 (c) and Nyquist plots of Fe 2 O 3 /GA and Fe 2 O 3 /G SCs (d).
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Three dimensional (3D) iron oxide (Fe2O3)/graphene aerogel (GA) hybrid (Fe2O3/GA) was synthesized by a novel in situ hydrothermal method. Due to the high surface area and sponge structure of GA, which facilitate the access of electrolyte to the internal surface of the graphene film, this 3D Fe2O3/GA composite consequently lead to a robust and super...
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... discharge current density was increased to 8 A g À1 , the Fe 2 O 3 /GA SC still exhibited considerable capacitance of 300 F g À1 , in contrast with 171 F g À1 for Fe 2 O 3 /G SC, indicating high rate capability of Fe 2 O 3 /GA SC (Fig. 6a). The capacitance of the Fe 2 O 3 /GA reported here at a current density of 1.5 A g À1 is also higher than that of many metal-oxide based anode materials and comparable to or even higher than that of the cathode materials such as MnO 2 Table S1. † The specic capacitance of the as- prepared Fe 2 O 3 /GA SC is superior to that of many ...
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... process at current density of 3 A g À1 . The as fabricated Fe 2 O 3 /GA SC device exhibit 328 and 297 F g À1 for the rst and 2200th cycles, respectively, corresponding to 90.5% of capacitance retention. While the Fe 2 O 3 /G SC shows 234 F g À1 and 190 F g À1 under the same testing conditions, corresponding to only 81% capacitance retention (Fig. 6b). The capacitance loss in the Fe 2 O 3 /G SC might be mainly caused by volume changes as a result of restacking of graphene layers and subsequent particle pulveri- zation. The 3D structure in the Fe 2 O 3 /GA SC electrode can release the mechanical stress during charge-discharge process, and therefore is benecial in maintaining the ...
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... of graphene layers and subsequent particle pulveri- zation. The 3D structure in the Fe 2 O 3 /GA SC electrode can release the mechanical stress during charge-discharge process, and therefore is benecial in maintaining the stability of the electrode structure. 26 The rst four galvanostatic charge- discharge curves at 2.5 A g À1 is shown in Fig. 6c, corroborates the result with cyclic stability. In order to investigate the resis- tance of the composites, AC impedance spectral analysis (EIS) for both devices was carried out. Nyquist plots were collected in the frequency range of 100 kHz to 0.1 Hz at open circuit potential (Fig. 6d). Z 0 and Z 00 refer to the real and imaginary ...
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... charge- discharge curves at 2.5 A g À1 is shown in Fig. 6c, corroborates the result with cyclic stability. In order to investigate the resis- tance of the composites, AC impedance spectral analysis (EIS) for both devices was carried out. Nyquist plots were collected in the frequency range of 100 kHz to 0.1 Hz at open circuit potential (Fig. 6d). Z 0 and Z 00 refer to the real and imaginary parts of the impedance. It can be observed that quantitatively, all Nyquist plot curves are same (straight line) in shape, having two distinct parts, a small semicircle arc at high frequency region and a linear part at low frequency region. The arc usually corresponds to the charge transfer ...
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... also tested at different scan rate. With increasing scan rate, there is no obvious distortion of the CV curves, indicating high rate capability (Fig. 7c). The CV curve of the 90 bent device at 20 mV aer 2000 cycles is similar to that of its initial state without any obvious change, showing high exibility and excellent stability of the device (Fig. S6 ...
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The performance of synergetic hybrid aerogel materials of vanadia and graphene as electrode materials in supercapacitors was evaluated. The hybrid materials were synthesized by two methods. In Method I, premade graphene oxide (GO) hydrogel was first chemically reduced by L-ascorbic acid and then soaked in vanadium triisopropoxide solution to obtain...
Citations
... Hence, it is concluded that the electrochemical performance of these pseudocapacitive MnO 2 and PANI can be improved by NG ae . Khattak et al. [70] prepared an Iron Oxide/ graphene aerogel nanocomposite (Fe 2 O 3 /GO) via a hydrothermal process. Because of the highly porous structure of graphene aerogel, the electrolyte can easily diffuse inside the surface of the graphene, so the produced Fe 2 O 3 /GA nanocomposite exhibits enhanced capacitance of 440 Fg −1 at 0.45 Ag −1 and more cyclic stability compared to Fe 2 O 3 /G composite. ...
Owing to the enchanting properties and applications possessed by graphene, scientific community showed enormous interest in the development of various graphene related materials. Among the varieties displayed by graphene, graphene aerogel, which is formed by the reduction of graphene oxide got immense attraction owing to the enhanced porosity, improved specific capacitance and increased surface area. The as-mentioned aerogel can be incorporated as a nanofiller for the fabrication of nanocomposites with improved properties which help them to widen their applications in energy storage, supercapacitor as well as sensors. The review provides a detailed investigation on the synthesis methods of graphene aerogel-based nanocomposites along with their properties and applications. Different areas including energy storage, sensors, supercapacitors, photocatalyst which can be flourished by the usage of graphene aerogel-based nanocomposites were discussed in a comprehensive manner followed by a focus on future perspectives.
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... This device outperforms most other relevant and reported devices. [22][23][24][25][26][27][28] Also, GCD tests of lithium-ion batteries (LIBs) ( Figure 7D) and SIBs ( Figure 7E) were performed on CA-8.4, CA@MnO 2 -8.4, ...
Designing and optimizing the pore structure of porous carbon electrodes is essential for diverse energy storage systems. In this study, an innovative approach spray phase‐inversion strategy was developed for the rapid and efficient fabrication of controlled porous carbon aerogel. Moreover, the aggregation structure of polyacrylonitrile is controlled by adjusting the Hansen's solubility parameter, thereby regulating the electrode material structure. Furthermore, the theoretical analysis of the spray phase‐inversion process revealed that this regulation process is jointly regulated by solvent hydrodynamic diameter and phase‐inversion kinetics. Through optimization, a novel porous carbon material was obtained that exhibited excellent performance as an electrode material. When utilized in supercapacitors for energy storage, it demonstrated a high specific capacitance of 373.1 F g⁻¹ in a 6 M KOH electrolyte solution. Simultaneously, it has been observed that the preparation strategy for porous electrodes offers notable advantages in terms of excellent designability, broad universality, simplicity, and high efficiency, thereby holding promise for large‐scale fabrication of diverse porous electrode materials and various types of electrodes for diverse energy storage applications.
... The obtained energy density and the power density values are presented in the form of the Ragone plot, as shown in Fig. 13c. The maximum energy density of the prepared ASC is 28.03 Wh Kg -1 at a power density of 586.68 W Kg -1 at a current density of 10 mAcm -2, and the values are superior to reported values in the literature [47][48][49]. Furthermore, as seen in Fig. 13d the fabricated ASC device showed a good coulomb efficiency of 94.5% and long-term cyclic stability of 94% over 5000 cycles at a scan rate of 10 mVs -1 , demonstrating its promising applicability in the field of supercapacitors. ...
Metal ion-doped transition metal oxides have been proposed as new electrode materials for developing high-performance energy storage devices. For supercapacitor applications, novel Chromium-doped iron oxide (Cr-doped α-Fe2O3) with sheet like morphology were fabricated by utilizing the Microwave route. The Cr-doped α-Fe2O3 nanosheets provided a large reaction area and fast electron transport which are desired for improving the electrochemical properties. The electrochemical properties of α-CrxFe2−xO3 (x = 0, 0.03, 0.06) electrodes were comprehensively studied using Cyclic voltammetry (CV), Galvanostatic Charging and discharging profiles and electrochemical impedance Spectroscopy in 3 M KOH electrolyte solution within a potential window of − 0.2 to 0.55 V. The 6% Cr-doped Hematite exhibited maximum redox activity because of its larger surface area and offered a specific capacitance of 1243 Fg⁻¹ at a scan rate of 5 mVs⁻¹ greater than pure α-Fe2O3 nanostructures. In addition, the 6% Cr doped sample showed less cyclic fatigue with 95.8% capacitance retention after 5000 CV cycles and a better conductivity with a resistance of only 2.57 Ω. Finally, an asymmetric Supercapacitor was designed, which showed a high energy density of 28.803 Wh Kg− 1 at a power density of 586.68 WKg⁻¹ and a good cyclic stability. The findings demonstrate that Cr-doped Hematite as electrode materials have potential application for high performance supercapacitors and may provide real solutions to the energy crisis.
... As observed in Figure 5, the existence of a pair of broad Red-Ox peaks around 0.7 V (shown by brown arrows in the figure) is due to the presence of the uncoated iron nanoparticles on the C1F carbon surface. 27 The presence of these Red-Ox peaks made us use the second acid wash to remove uncoated iron particles to produce C2F samples. As can be seen in the figure, the SC with both electrolytes shows a rectangular shape, especially at low sweep rates. ...
According to the technology of carbon-based supercapacitors, modifying the structure of carbon as an active electrode material leads to an increase in capacitance. A modification involves introducing heteroatoms such as nitrogen into the carbon structure and composing it with metals such as iron. In this research, an anionic source called ferrocyanide was used to produce N-doped carbon consisting of iron nanoparticles. In fact, ferrocyanide was located as a guest between the layers of a host material, which is zinc hydroxide in the α phase. This new nanohybrid material was then heat-treated under Ar, and the heated product after acid washing was iron nanoparticles wrapped with N-doped carbon materials. This material was used as an active material in the production of symmetric supercapacitors with different organic (TEABF4 in acetonitrile) and aqueous (sodium sulfate) electrolytes as well as a new electrolyte (KCN in methanol). Accordingly, the supercapacitor made by the N/Fe-carbon active material and the organic electrolyte showed a capacitance value of 21 F/g at a current density of 0.1 A/g. This value is comparable to and even higher than the values observed in commercial supercapacitors.
... In this synthesized method, the composite offered the specific capacitance of 504, 138 and 193Fg − 1 at different hybrid materials like Fe 2 O 3 nanorods/rGO, Fe 2 O 3 nanoparticles/rGO and Fe 2 O 3 gathered nanorods/ rGO. Tang et al. [106] prepared a novel class of composite containingiron oxide and graphene aerogel, which showed excellent performance. At different scan rates, the device with a 90 • bending angle was also examined. ...
... The iron oxide/GA electrode shows ahigh specific capacitance of 440 Fg − 1 for different bending angles, capacitance retention 90 % over 2200 cycles also indicating the excellent cycling stability. It can be seen that all Nyquist plot curves are quantitatively the same (straight line) in shape, with two unique sections, a little semicircle arc at high frequency and a linear part at low frequency in Fig. 4 (e) [106]. ...
Nanocomposite electrodes containing various dimensional structures of nanomaterials usually exhibit superior performances in supercapacitor applications because of their advantages on greater specific surface area, directional ion diffusion/charge transport roots, and structural durability etc. The novelty of the present study is that it reports recent advances of two-dimensional (2D) materials, such as graphene, MXene, transition metal
dichalcogenides (TMDs), and layered double hydroxides (LDHs), used for boosting the performance of metal oxide-based electrode (e.g., RuO2, MnO2, NiO, Fe3O4, Co3O4) in supercapacitors applications. Herein, the constituents, structural features, electrochemical behavior and the nature properties of several metal oxide-based
electrodes for supercapacitors are reviewed. The 2D material/metal oxide electrodes based supercapacitors have a high commercial potential due to their chemical stability, power and energy densities, specific capacitance, long cycle life, good electronic properties, and efficient ionic transport at the electrode-electrolyte
interface as visualized. Finally, the future prospects and challenges for the development of 2D material/metal oxide nanocomposite electrodes in next generation supercapacitors have been summarized.
... To improve the supercapacitor performance, iron oxside was co-located with carbonaceous materials. Khattak et al used iron oxide/graphene aerogel hybrids in the electrodes of supercapacitor by a novel in situ hydrothermal method [22]. These hybrids supercapacitor exhibited a high specific capacitance of 440 F g −1 and 90% capacitance retention after 2000 cycles. ...
The performance of supercapacitors strongly depends on the electrochemical characterizations of electrode materials. Herein, a composite material consisted of iron(III) oxide (Fe2O3) and multilayer graphene-wrapped copper nanoparticles (Fe2O3/MLG-Cu NPs) is fabricated on a flexible carbon cloth (CC) substrate via two-step synthesis process for supercapacitor application. Where, MLG-Cu NPs are prepared on CC by one-step chemical vapor deposition (CVD) synthesis approach; thereafter, the Fe2O3 is further deposited on the MLG-Cu NPs/CC via successive ionic layer adsorption and reaction (SILAR) method. The related material characterizations of Fe2O3/MLG-Cu NPs are well investigated by scanning electron microscopic (SEM), high resolution transmission electron microscopy (HR-TEM), Raman spectrometer and X-ray photoelectron spectroscopy (XPS); the electrochemical behaviors of the pertinent electrodes are studied by cyclic voltammogram (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) measurements. The flexible electrode with Fe2O3/MLG-Cu NPs composites exhibits the best specific capacitance of 1092.6 mF cm-2 at 1 A g-1, which is much higher than those of electrodes with Fe2O3 (863.7 mF cm-2), MLG-Cu NPs (257.4 mF cm-2), multilayer graphene hollow balls (MLGHBs, 14.4 mF cm-2) and Fe2O3/MLGHBs (287.2 mF cm-2). Fe2O3/MLG-Cu NPs electrode also exhibits an excellent GCD durability, and its capacitance remains 90% of its original value after 1200 cycles of the GCD process. Finally, a supercapacitor system consisted of four Fe2O3/MLG-Cu NPs/CC electrodes can efficiently power various light-emitting diodes (i.e., red, yellow, green, and blue lights), demonstrating the practical application of Fe2O3/MLG-Cu NPs/CC electrode.
... Whereas, after the addition of 3 and 5 wt% rGO, the BFO particles become smaller and have a more porous microstructure (Fig. 2c, d). By increasing rGO concentration, more rGO surfaces are available, and BFO can nucleate more on rGO nanosheets, thus decreasing their particle size, which is in agreement with some previous studies [26][27][28]. Consequently, BGO thin films, especially BGO3, possess micro and nano porosity, which provides a high surface-area-tovolume ratio. Besides, the presence of BFO between rGO nanosheets may prevent the cluster formation of rGO nanosheets originated by the van der Waals force, leading to rapid charge carrier transfer [28]. ...
... Consequently, BGO thin films, especially BGO3, possess micro and nano porosity, which provides a high surface-area-tovolume ratio. Besides, the presence of BFO between rGO nanosheets may prevent the cluster formation of rGO nanosheets originated by the van der Waals force, leading to rapid charge carrier transfer [28]. Also, The FESEM cross-sectional images of BFO, BGO1, BGO2, and BGO3 thin films are shown in Fig. 2e-h. ...
In this study, a facile chemical approach was utilized to successfully fabricate a porous bismuth ferrite (BiFeO3, BFO)/reduced graphene oxide (rGO) nanocomposite thin film as a photoanode for photoelectrochemical (PEC) water splitting. The BFO nanoparticles possess a pure rhombohedral distorted perovskite crystal structure and are grafted onto rGO nanosheets. BFO/rGO (BGO) thin film has smaller nanoparticles (around 100 nm) and higher porosity which provides a higher surface area compared to BFO. Moreover, BGO exhibits higher visible absorption, a narrower band gap energy of 1.95 eV, and a lower recombination rate of charge carriers. The BGO photoanode has a maximum photocurrent density of 0.451 mA.cm⁻² at 1.23 V versus the reversible hydrogen electrode (RHE) under 100 mW.cm⁻² illumination which is 2.5 times more than the BFO photoanode. The applied bias photon-to-current efficiency (ABPE) of BGO nanocomposite film is 0.21%, which is approximately 2.5 times that of BFO. The obtained results reveal an intimate heterostructure between BFO nanoparticles and rGO nanosheets. The charge separation and transfer of BFO are significantly boosted by incorporating the rGO. This study sheds light on the mechanism insights of enhanced PEC water splitting in BFO/rGO thin film, offering a new approach to the design and fabrication of high-efficiency photoanodes.
... A porous carbonized cotton/ZnO/CuS composite electrode showed a specific capacitance of 1830 mF cm −2 at 2 mA cm −2 and 74% retention with the current density increasing from 2 to 10 mA cm −2 and a loss of 14.8% of the initial capacitance after 5000 cycles [116]. An Fe 2 O 3 /Graphene aerogel hybrid electrode was used to build a highly flexible all-solid-state symmetric supercapacitor device, which could be bent by several angles providing a high specific capacitance, i.e., 440 Fg −1 and 90% capacitance retainment over 2200 cycles [117]. Confined anatase TiO 2 nanoparticles were achieved in conductive activated carbon interconnected nanopores. ...
Personal, portable, and wearable electronics have become items of extensive use in daily life. Their fabrication requires flexible electronic components with high storage capability or with continuous power supplies (such as solar cells). In addition, formerly rigid tools such as electrochromic windows find new utilizations if they are fabricated with flexible characteristics. Flexibility and performances are determined by the material composition and fabrication procedures. In this regard, low-cost, easy-to-handle materials and processes are an asset in the overall production processes and items fruition. In the present mini-review, the most recent approaches are described in the production of flexible electronic devices based on NiO as low-cost material enhancing the overall performances. In particular, flexible NiO-based all-solid-state supercapacitors, electrodes electrochromic devices, temperature devices, and ReRAM are discussed, thus showing the potential of NiO as material for future developments in opto-electronic devices.
... The ASC could deliver an energy density of 12 Wh kg −1 at a load current-density of 0.1 A g −1 . At a load current-density of 5 A g −1 , the ASC achieves a power density as high as 11.8 kW kg −1 along with an energy density of 6.5 Wh kg −1 , which outperforms many other symmetric and asymmetric SCs including, α-Fe 2 O 3 NRs//MnO 2 ASC (7.9 Wh kg −1 , 1918 W kg −1 ), 5 Fe 2 O 3 /GA-based symmetric SC (6.7 Wh kg −1 , 1.6 kW kg −1 ), 32 Ni(OH) 2 //F2RF-150 ASC (4.1 Wh kg −1 , 66 1 W kg −1 ), 33 MnO 2 -CNP symmetric SC (4.8 Wh kg −1 , 14 kW/kg), 34 MnO 2 /3D Graphene-based symmetric SC (6.8 W h kg −1 , 62 W kg −1 ), 35 MnFe 2 O 4 //AC ASC (10.25 Wh kg −1 , 3076 W kg −1 for), 36 etc. Cycling performance of the ASC is evaluated during 15,000 CV cycles at a scan rate of 100 mV s -1 as shown in Fig. 6b. The ASC could retain 80% of its initial capacitance during this period. ...
... The use of highenergy density pseudo-capacitors is seriously restricted due to their low electronic conductivities. The assembly hybrid materials (EDLC+pseudocapacitive) are a fascinating combination that offers high energy density and power density as compared to bare EDLC and pseudocapacitors [9,45,46]. Aerogels consist of porous solid-state materials with extraordinary properties such as large open pores, extremely low density, and high surface area [47][48][49]. The aerogel made up of a 3D solid network with large pores having air-filled hence form a highly cross-linked structure. ...
Graphene and graphene-based hybrid materials have emerged as an outstanding supercapacitor electrode material primarily because of their excellent surface area, high electrical conductivity, and improved thermal, mechanical, electrochemical cycling stabilities. Graphene alone exhibits electric double layer capacitance (EDLC) with low energy density and high power density. The use of aerogels in a supercapacitor is a pragmatic approach due to its extraordinary properties like ultra-lightweight, high porosity and specific surface area. The aerogels encompass a high volume of pores which leads to easy soak by the electrolyte and fast charge-discharge process. Graphene aerogels assembled into three-dimensional (3D) architecture prevent there stacking of graphene sheets and maintain the high surface area and hence excellent cycling stability and rate capacitance. However, the energy density of graphene aerogels is limited due to EDLC type of charge storage mechanism. Consequently, 3D graphene aerogel coupled with pseudocapacitive materials such as transition metal oxides, metal hydroxides, conducting polymers, nitrides, chalcogenides show an efficient energy density and power density performance due to the presence of both types of charge storage mechanisms. This laconic review focuses on the design and development of graphene-based aerogel in the field of the supercapacitor. This review is an erudite article about methods, technology and electrochemical properties of graphene aerogel.
