We investigated different molar concentrations of cobalt precursor intercalated reduced graphene oxide (rGO) as possible electrode materials for supercapacitors. Cobalt oxide (Co 3 O 4 ) nanocubes ...intercalated reduced graphene oxides (rGO) were synthesized via a facile hydrothermal method. It has been found that the Co 3 O 4 particles with a cubical shape are decorated on rGO matrix with an average size of ∼45 nm. The structural crystallinity of rGO–Co 3 O 4 composites was examined by X-ray diffraction (XRD). Raman spectroscopy confirmed the successful reduction of GO to rGO and effective interaction between Co 3 O 4 and the rGO matrix. The electrochemical performances of rGO–Co 3 O 4 electrodes were examined using cyclic voltammetry and charge–discharge techniques. The maximum specific capacitance (278 F g −1 ) is observed at current density of 200 mA g −1 in the C2 electrode resulting from effective ion transfer and less particle aggregation of Co 3 O 4 on the rGO matrix than in the other electrodes. C2 exhibits good rate capability and excellent long-term cyclic stability of 91.6% for 2000 cycles. The enhanced electrochemical performance may result from uniform intercalation of cobalt oxide over the rGO. These results suggest that the Co 3 O 4 intercalated rGO matrix could play a role in improved energy storage capability.
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IJS, KILJ, NUK, UL, UM, UPUK
Nicotinamide Adenine Dinucleotide (NADH) is an important coenzyme in the human body that participates in many metabolic reactions. The impact of abnormal concentrations of NADH significantly causes ...different diseases in human body. Electrochemical detection of NADH using bare electrode is a challenging task especially in the presence of main electroactive interferences such as ascorbic acid (AA), uric acid (UA) and dopamine (DA). Modified electrodes have been widely explored to overcome the problems of poor sensitivity and selectivity occurred from bare electrodes. This review gives an overview on the progress of using conducting polymers, polyelectrolyte and its composites (co-polymer, carbonaceous, metal, metal oxide and clay) based modified electrodes for the sensing of NADH. In addition, developments on the fabrication of numerous conducting polymer composites based modified electrodes are clearly described.
•We review the conducting polymer and its composite materials for NADH sensing.•The detection mechanisms and the advantages of materials are emphasized.•Future perspectives and possible challenges in this area are outlined.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
This article presents the effect of different calcination temperatures on the structural, morphological and capacitance of nickel phosphate (Ni
3
(PO
4
)
2
) as an electrode material for ...supercapacitor applications. Ni
3
(PO
4
)
2
was synthesized
via
a sonochemical method followed by calcination at different temperatures (300, 600 and 900 °C, denoted as N300, N600 and N900, respectively). The phase structure and purity of Ni
3
(PO
4
)
2
were confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The surface morphologies showed that the particle size increased with increasing the calcination temperatures. The electrochemical performance of N300, N600 and N900 were investigated using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) in a 1 M KOH electrolyte. It was found that N300 exhibited the maximum specific capacity of 620 C g
−1
at 0.4 A g
−1
, which was significantly higher than N600 (46 C g
−1
) and N900 (14 C g
−1
). Here, the enhanced electrochemical performance was obtained due to the amorphous structure and augmentation of the redox active sites of the N300 particles. Additionally, the fabricated N300//activated carbon based asymmetric supercapacitor can be cycled reversibly at a cell voltage of 1.45 V. The device exhibited an energy density of 76 W h kg
−1
and a power density of 599 W kg
−1
with life cycles of 88.5% capacitance retention after 3000 cycles.
This article presents the effect of different calcination temperatures on the structural, morphological and capacitance of nickel phosphate (Ni
3
(PO
4
)
2
) as an electrode material for supercapacitor applications.
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IJS, KILJ, NUK, UL, UM, UPUK
A liquid electrolyte based on binary solvent systems of ethylene carbonate (EC), dimethyl carbonate (DMC) and lithium bis(trifluoromethane)sulfonimide (LiTFSI) salt incorporating with acrylic acid ...(AA) monomer was synthesized. The ionic conductivity studies revealed that the conductivity of the liquid electrolyte was enhanced from 2.16 × 10−3 to 2.24 × 10−3 S cm−1 at room temperature after the addition of 0.1 mol/kg AA due to the presence of a carbonyl group in AA structure. The viscosity and the temperature dependence of the ionic conductivity followed an Arrhenius equation. Interactions of the EC/DMC, LiTFSI and AA were characterized by Fourier transform infrared spectroscopy analysis. The electrochemical performance of the liquid electrolyte towards electric double layer capacitor (EDLC) was investigated using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques. EDLC performances demonstrated that the supercapacitors exhibited specific capacitance ∼24.01 F/g at 5 mV/s. The life cycle test revealed that supercapacitor cell incorporated with synthesized liquid electrolyte possessed excellent stability and coulombic efficiency even after 4000 cycles.
•Electrolyte based on Ethylene carbonate, dimethyl carbonate and LiTFSI was prepared.•Acrylic acid was added in above electrolyte and its affect was analysed.•Ionic conductivity studies revealed that sample AA 0.1 has highest conductivity.•The synthesized electrolyte showed enhance performance for supercapacitor.•The synthesized electrolyte based supercapacitor was highly stable.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
A facile and fast approach for the synthesis of a nanostructured nickel hydroxide (Ni(OH)2) via sonochemical technique is reported in the present study. The X-ray diffraction results confirmed that ...the synthesized Ni(OH)2 was oriented in β-phase of hexagonal brucite structure. The nanostructured Ni(OH)2 electrode exhibited the maximum specific capacitance of 1256F/g at a current density of 200mA/g in 1M KOH(aq). Ni(OH)2 electrodes exhibited the pseudocapacitive behavior due to the presence of redox reaction. It also exhibited long-term cyclic stability of 85% after 2000 cycles, suggesting that the nanostructured Ni(OH)2 electrode will play a promising role for high performance supercapacitor application.
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•Nanostructured nickel hydroxide was synthesized via one step process.•The non-aggregated β-phase of hexagonal brucite structure was observed.•It exhibited maximum specific capacitance of 1256F/g at 200mA/g.•It exhibited long-term cyclic stability of 93% after 1000 cycles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Dopamine (DA) is an important catecholamine neurotransmitter in the mammalian central nervous system that influences several physiological functions. The impact of DA levels within the human body ...significantly affects the body functions. Maintaining DA level is essential and the electrochemical detection methods are often used to detect the DA level to regulate the body function. In this review, graphene (functionalized graphene and N-doped graphene) and its composites (metal, metal oxide, polymer, carbonaceous materials, clay, zeolite, and metal-organic framework based graphene composites) modified electrodes with their improved sensing performance towards DA along with several interfering species are described. Further, recent developments on the fabrication of various graphene based composite modified electrodes are also presented. Some important strategies to improve the selectivity and sensitivity towards DA with graphene based composite modified electrodes are also described.
In this review, the recent progress in the electrochemical sensing of dopamine with various graphene and their nanocomposite materials modified electrodes are presented.
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IJS, KILJ, NUK, UL, UM, UPUK
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The development of low-cost fuel cell technology has involved substantial research on platinum-free or non-platinum group metal (non-PGM) catalysts for oxygen reduction reactions ...(ORR) in proton exchange membrane fuel cells. However, due to macroscale degradation and flooding issues in fuel cell systems, catalyst development has faced significant challenges in rapid active site degradation over a short time. This review presents the impacts of the non-PGM catalyst structure on the ORR activity and single-cell performance. A balance in the micropores, mesopores and macropores is sought to ensure high accessibility to the active sites, a high active site density, and good water management at the electrode layer to prevent active site blockage. The unsatisfactory single-cell performance of non-PGM electrodes also potentially arises from the conventional catalyst ink-casting technique. This review also provides insight into the necessary strategies for producing non-PGM MEAs via proper porous architecture and innovative catalyst casting techniques to develop promising low-cost PEMFC technology.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Solvent evaporation and leakage of liquid electrolytes that restrict the practicality of dye-sensitized solar cells (DSSCs) motivate the quest for the development of stable and ionic conductive ...electrolyte. Gel polymer electrolyte (GPE) fits the criteria, but it still suffers from low efficiency due to insufficient segmental motion within the electrolytes. Therefore, incorporating metal oxide nanofiller is one of the approaches to enhance the performance of electrolytes due to the presence of cross-linking centers that can be coordinated with the polymer segments. In this research, polymer composite gel electrolytes (PCGEs) employing poly (vinyl butyral-co-vinyl alcohol-co-vinyl acetate) (P(VB-co-VA-co-VAc)) terpolymer as host polymer, tetrapropylammonium iodide (TPAI) as dopant salt, and copper oxide (CuO) nanoparticles as the nanofillers were produced. The CuO nanofillers were synthesized by sonochemical method and subsequently calcined at different temperatures (i.e., 200, 350, and 500 °C), denoted as CuO-200, CuO-350, and CuO-500, respectively. All CuO nanoparticles have different shapes and sizes that are connected in a chain which impact the amorphous phase and the roughness of the surface, proven by the structural and the morphological analyses. It was found that the PCGE consisting of CuO-350 exhibited the highest ionic conductivity of 2.54 mS cm−1 and apparent diffusion coefficient of triiodide of 1.537 × 10−4 cm2 s−1. The enhancement in the electrochemical performance of the PCGEs is correlated with the change in shape (rod to sphere) and size of CuO particles which disrupted the structural order of the polymer chain, facilitating the redox couple transportation. Additionally, a DSSC was fabricated and achieved the highest power conversion efficiency of 7.05% with JSC of 22.1 mA cm−2, VOC of 0.61 V, and FF of 52.4%.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
NASICON-like Na
3
Zr
2
(SiO
4
)
2
PO
4
(NZSP) ceramic solid electrolyte with high ionic conductivity, safety, and durability becomes the main focus and attention as an alternative for traditional ...liquid electrolytes. NZSP containing NH
4
H
2
PO
4
and Na
3
PO
4
⋅12H
2
O as the phosphate source has been extensively studied as a solid electrolyte, but a deep understanding of the relationship between crystal growth and ionic conductivity is still lacking. Herein, we synthesized NZSP via a solid-state reaction using NaH
2
PO
4
as the phosphate source. The impact of different sintering holding times on the crystal phase, microstructure, ionic conductivity, and relaxation time of NZSP solid electrolytes was investigated. Microstructure studies revealed that the faceted NZSP sintered at 1100 °C for 24 h has the lowest formation of ZrO
2
and highest densification with the least pores. In addition, the sample achieved the highest room temperature ionic conductivity (4.11 ⨯ 10
−4
S cm
−1
) and the shortest relaxation time (0.4 μs), which are also crucial factors for the development of rechargeable all-solid-state batteries (ASSBs).
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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
This work reports on synthesis of zinc oxide/reduced graphene oxide (ZnO/rGO) nanocomposites in the presence of diethylenetriamine (DETA) via a facile microwave method. The X-ray diffraction (XRD) ...patterns of the nanocomposites correspond to the ZnO hexagonal phase wurtzite structure. The high-resolution transmission electron microscopy (HRTEM) images revealed that the ZnO nanorods, with an average length : diameter ratio of 10, were successfully deposited on the rGO sheets. Under the irradiation of sunlight, the nanocomposites showed enhanced adsorption-photocatalysis by more than twofold and photocurrent response by sixfold compared to the ZnO. The excellent photoactivity performance of the nanocomposites is contributed by smaller ZnO nanorod and the presence of rGO that acts as a photosensitizer by transferring electrons to the conduction band of ZnO within the nanocomposite during sunlight illumination.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
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