This article presents the effect of polyaniline (PANI) embedded copper cobaltite (CuCo2O4) as an electrode material for high performance supercapacitor application. The composite of PANI-CuCo2O4 was ...prepared via blending process. The formation of PANI-CuCo2O4 composite was confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The surface morphologies showed that the spinel structure of CuCo2O4 (average particle size of 30nm) was well distributed on PANI matrix, suggest the effective intercalation of CuCo2O4 with PANI matrix. The electrochemical properties of CuCo2O4, PANI and PANI-CuCo2O4 composite were investigated using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) in 1M of KOH as an aqueous electrolyte. The PANI-CuCo2O4 composite showed the improved specific capacitance of 403C/g than that of pure CuCo2O4 and PANI.The enhanced electrochemical performance was obtained due to the augmentation of redox active sites and synergetic effect between PANI and CuCo2O4 nanoparticles. Additionally, the fabricated (activated carbon (AC)/PANI-CuCo2O4) asymmetric supercapacitor device can be cycled reversibly at a cell voltage of 1.5V, which exhibited excellent electrochemical performances with an energy density of 76Wh/kg and a power density of 599W/kg. It also presented a superior life cycle with 94% capacitance retention after 3000 cycles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The present paper is focused on the structure, microstructure, and electrical properties of Ca (calcium)- and Dy (dysprosium)-doped ceria electrolyte materials. The CaDDC (Ce
0.8
Dy
0.175
Ca
0.025
O
...2-δ
) sample was prepared through a modified sol–gel low-temperature process using sucrose and pectin. Rietveld analysis of powder x-ray diffraction (XRD) patterns confirms the cubic structure with a single phase. The Raman spectroscopy studies confirm the improved oxygen vacancies for the sample CaDDC over pure ceria. The scanning electron microscopy (SEM) images showed the highly dense surface. Energy-dispersive spectroscopy (EDS) confirms the sample chemical composition. Impedance spectroscopic studies were carried out to analyze the electrical properties. Migration energy (
E
m
) and association energy (
E
asso
.
) were calculated from the dielectric relaxation process for oxide ion migration. Relaxation peaks were observed in tangent loss due to the presence of defect pairs. Modulus analysis showed a single relaxation peak, which indicates the reorientation of defect associates. The Ce
0.8
Dy
0.175
Ca
0.025
O
2-δ
sample exhibits improved conductivity of 1.23 × 10
–2
S/cm at 600°C with an activation energy of 0.89 eV.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Excellent anti-corrosive properties of grapheme.•Pure graphene coatings and graphene composite coatings were used as anti-corrosive.•Anti-corrosion mechanism, optimization measures, and corrosion ...resistance of grapheme.•Explanation on its existing problems, challenges, and future research directions have been highlighted.
In various academic and industrial interests, graphene has achieved remarkable attention mainly by its distinctive chemical, mechanical, thermal, electrical and excellent anti-corrosion properties respectively, whereby the previous and ongoing researches have shown positive outcomes and its respective results achieved were at a satisfactory level. Over the last few years, the scope of the research on the applications of graphene based anti-corrosion has been intensely broadened and consists of two components, firstly pure graphene coatings and secondly graphene composite coatings. In the formulation of polymeric coatings, due to graphene and its derivatives having extraordinary lamellar structure, this material is highly suitable as anti-corrosive additives. Graphene creates pathways that are highly tortuous, thereby preventing the water and oxygen molecules to be diffused to the metal-based surface of materials, resulting in the protection of metal from oxidation and corrosion. Therefore, comprehensively reviewed in this article is the graphene-based coatings applications to metal anti-corrosion. First, the basic fundamentals of anti-corrosive coating technology will be discussed followed by and the current progress. Second, in detail, the preparation of graphene followed by pure graphene coatings methods respectively are illustrated. Third, the pure graphene coating in terms of corrosion resistance will be discussed, followed by detailed explanation on its existing problems and optimization respectively. Next, associated with graphene-based organic coatings, the graphene and graphene oxide dispersion and modification will be discussed, followed by the mechanism of barrier properties of graphene as well as the influence of the electrical conductivity. The anti-corrosion mechanism, optimization measures, corrosion resistance, and existing problems are summarized for the composite coatings fabricated using graphene. The challenges and future developments of anticorrosive graphene coatings are finally discussed and proposed, and their potential applications are discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the present review, we focused on the fundamental concepts of hydrogels—classification, the polymers involved, synthesis methods, types of hydrogels, properties, and applications of the hydrogel. ...Hydrogels can be synthesized from natural polymers, synthetic polymers, polymerizable synthetic monomers, and a combination of natural and synthetic polymers. Synthesis of hydrogels involves physical, chemical, and hybrid bonding. The bonding is formed via different routes, such as solution casting, solution mixing, bulk polymerization, free radical mechanism, radiation method, and interpenetrating network formation. The synthesized hydrogels have significant properties, such as mechanical strength, biocompatibility, biodegradability, swellability, and stimuli sensitivity. These properties are substantial for electrochemical and biomedical applications. Furthermore, this review emphasizes flexible and self-healable hydrogels as electrolytes for energy storage and energy conversion applications. Insufficient adhesiveness (less interfacial interaction) between electrodes and electrolytes and mechanical strength pose serious challenges, such as delamination of the supercapacitors, batteries, and solar cells. Owing to smart and aqueous hydrogels, robust mechanical strength, adhesiveness, stretchability, strain sensitivity, and self-healability are the critical factors that can identify the reliability and robustness of the energy storage and conversion devices. These devices are highly efficient and convenient for smart, light-weight, foldable electronics and modern pollution-free transportation in the current decade.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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•Co3O4 nanograin-decorated rGO composite was fabricated via hydrothermal route.•rGO-Co3O4 nanograin composite was used for modification of electrode.•rGO-Co3O4 nanograins showed ...excellent catalytic performance towards dopamine detection.•rGO-Co3O4 nanocomposite selectively detected dopamine in the presence of interfering species.
A sensitive and selective detection of dopamine (DA) by a sensor based on cobalt oxide (Co3O4) nanograin-decorated reduced graphene oxide (rGO) composite modified glassy carbon electrode (GCE) is reported. The rGO-Co3O4 nanograin composites are synthesized by a facile hydrothermal route and optimized by varying the contents of rGO (5.7, 7.4, 9.1 and 10.7wt%, denoted as C1, C2, C3 and C4 respectively). The crystallinity of the composite is examined by X-ray diffraction (XRD). Raman spectrum revealed the successful reduction of graphene oxide (GO) into rGO. The surface morphology through field emission scanning electron microscopy (FESEM) revealed that the granular-shaped Co3O4 are decorated on rGO matrix with an average particle size of∼35nm. For electrochemical oxidation of DA, glassy carbon electrode (GCE) is modified with nanocomposites. Cyclic voltammetric results show that C3 modified GCE exhibit enhanced electrocatalytic performance in terms of oxidation potential and peak current in comparison to those of bare GCE, Co3O4 nanograins, C1, C2 and C4 modified GCE. The choronoamperometric studies indicate that C3 modified GCE exhibit a low detection limit of (S/N=3) 0.277μM in the linear range of 1–30μM. In addition, C3 demonstrates good selectivity towards the detection of DA in the presence of a 100-fold higher concentration of ascorbic acid, glucose and uric acid as the interfering species. The electrochemical sensing studies suggest that 3D rGO-Co3O4 nanograins endow excellent catalytic activity, high selectivity and sensitivity towards DA.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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•Nickel oxide with different particle sizes are developed by a facile process.•The smaller particle size of 6nm with face centered cubic structure was observed.•CV and EIS study shows ...the pseudocapacitive behavior of NiO nanostructures.•NiO with smaller particle size exhibited enhanced specific capacitance.
In this work, we demonstrate the influence of nickel oxides with divergent particle sizes as the working electrodes for supercapacitor application. The nanostructured nickel oxide (NiO) is synthesized via facile sonochemical method, followed by calcination process. The crystallinity and surface purity of prepared samples are clearly examined by X-ray diffraction and Raman analysis. NiO crystallinity is significantly increased with increasing calcination temperatures. The surface analysis confirmed that the calcination at 250°C exhibited nanoclutser like NiO with average particle size of ∼6nm. While increasing the calcination temperature beyond 250°C, hexagonal shaped NiO is observed with enhanced particle sizes. The electrochemical performance confirmed the good redox behavior of NiO electrodes. Moreover, NiO with average particle size of ∼6nm exhibited high specific capacitance of 449F/g at a scan rate of 5mV/s compared to other samples with particle sizes of ∼21nm (323F/g) and ∼41nm (63F/g). This is due to the good ion transfer mechanism and effective electrochemical utilization of the working electrode.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Deep Neural Networks (DNNs) have been extensively used in many areas including image processing, medical diagnostics and autonomous driving. However, DNNs can exhibit erroneous behaviours that may ...lead to critical errors, especially when used in safety-critical systems. Inspired by testing techniques for traditional software systems, researchers have proposed neuron coverage criteria, as an analogy to source code coverage, to guide the testing of DNNs. Despite very active research on DNN coverage, several recent studies have questioned the usefulness of such criteria in guiding DNN testing. Further, from a practical standpoint, these criteria are white-box as they require access to the internals or training data of DNNs, which is often not feasible or convenient. Measuring such coverage requires executing DNNs with candidate inputs to guide testing, which is not an option in many practical contexts. In this paper, we investigate diversity metrics as an alternative to white-box coverage criteria. For the previously mentioned reasons, we require such metrics to be black-box and not rely on the execution and outputs of DNNs under test. To this end, we first select and adapt three diversity metrics and study, in a controlled manner, their capacity to measure actual diversity in input sets. We then analyze their statistical association with fault detection using four datasets and five DNNs. We further compare diversity with state-of-the-art white-box coverage criteria. As a mechanism to enable such analysis, we also propose a novel way to estimate fault detection in DNNs. Our experiments show that relying on the diversity of image features embedded in test input sets is a more reliable indicator than coverage criteria to effectively guide DNN testing. Indeed, we found that one of our selected black-box diversity metrics far outperforms existing coverage criteria in terms of fault-revealing capability and computational time. Results also confirm the suspicions that state-of-the-art coverage criteria are not adequate to guide the construction of test input sets to detect as many faults as possible using natural inputs.
There has been significant progress in the last few decades in addressing the biomedical applications of polymer hydrogels. Particularly, stimuli responsive hydrogels have been inspected as elegant ...drug delivery systems capable to deliver at the appropriate site of action within the specific time. The present work describes the synthesis of pH responsive semi-interpenetrating network (semi-IPN) hydrogels of N-succinyl-chitosan (NSC) via Schiff base mechanism using glutaraldehyde as a crosslinking agent and Poly (acrylamide-co-acrylic acid)(Poly (AAm-co-AA)) was embedded within the N-succinyl chitosan network. The physico-chemical interactions were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and field emission scanning electron microscope (FESEM). The synthesized hydrogels constitute porous structure. The swelling ability was analyzed in physiological mediums of pH 7.4 and pH 1.2 at 37°C. Swelling properties of formulations with various amounts of NSC/ Poly (AAm-co-AA) and crosslinking agent at pH 7.4 and pH 1.2 were investigated. Hydrogels showed higher swelling ratios at pH 7.4 while lower at pH 1.2. Swelling kinetics and diffusion parameters were also determined. Drug loading, encapsulation efficiency, and in vitro release of 5-fluorouracil (5-FU) from the synthesized hydrogels were observed. In vitro release profile revealed the significant influence of pH, amount of NSC, Poly (AAm-co-AA), and crosslinking agent on the release of 5-FU. Accordingly, rapid and large release of drug was observed at pH 7.4 than at pH 1.2. The maximum encapsulation efficiency and release of 5-FU from SP2 were found to be 72.45% and 85.99%, respectively. Kinetics of drug release suggested controlled release mechanism of 5-FU is according to trend of non-Fickian. From the above results, it can be concluded that the synthesized hydrogels have capability to adapt their potential exploitation as targeted oral drug delivery carriers.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this paper, we review different types of polymer electrolytes, recent approaches and technological applications of polymer electrolytes. The report first discusses the characteristics, advantages ...and applications for three types of polymer electrolytes: gel polymer electrolytes, solid polymer electrolytes and composite polymer electrolytes. Next, we discuss the features and performance of different polymer hosts based on some important and recently published literature. Recent progress of some approaches used in improving the performance of the polymer electrolytes is highlighted. The last part of the review includes the technological applications of some electrical energy storing/converting devices: electrochemical capacitors, batteries, fuel cells and dye-sensitized solar cells. It is also stressed that the technological advancement in the polymer electrolytes plays a pivotal role in the development of energy storing/converting systems.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Biopolymer electrolytes exhibit VTF relationship.•Addition of ionic liquid in polymer electrolytes reduces Tg.•Ionic liquid-doped polymer electrolyte has better electrochemical properties of EDLC.
...Biopolymer electrolytes containing corn starch, lithium hexafluorophosphate (LiPF6) and ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BmImPF6) are prepared by solution casting technique. Temperature dependence-ionic conductivity studies reveal Vogel–Tamman–Fulcher (VTF) relationship which is associated with free volume theory. Ionic liquid-based biopolymer electrolytes show lower glass transition temperature (Tg) than ionic liquid-free biopolymer electrolyte. X-ray diffraction (XRD) studies demonstrate higher amorphous region of ionic liquid-added biopolymer electrolytes. In addition, the potential stability window of the biopolymer electrolyte becomes wider and stable up to 2.9V. Conclusively, the fabricated electric double layer capacitor (EDLC) shows improved electrochemical performance upon addition of ionic liquid into the biopolymer electrolyte. The specific capacitance of EDLC based on ionic liquid-added polymer electrolyte is relatively higher than that of ionic liquid-free polymer electrolyte as depicted in cyclic voltammogram.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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