Navaneethan Duraisamy

Facile sonochemical synthesis of nanostructured NiO with different particle sizes and its electrochemical properties for supercapacitor application

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.

Enhanced electrochemical performance of cobalt oxide nanocube intercalated reduced graphene oxide for supercapacitor application

We investigated different molar concentrations of cobalt precursor intercalated reduced graphene oxide (rGO) as possible electrode materials for supercapacitors. Cobalt oxide (Co3O4) nanocubes intercalated reduced graphene oxides (rGO) were synthesized via a facile hydrothermal method. It has been found that the Co3O4 particles with a cubical shape are decorated on rGO matrix with an average size of ∼45 nm. The structural crystallinity of rGO–Co3O4 composites was examined by X-ray diffraction (XRD). Raman spectroscopy confirmed the successful reduction of GO to rGO and effective interaction between Co3O4 and the rGO matrix. The electrochemical performances of rGO–Co3O4 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 Co3O4 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 Co3O4 intercalated rGO matrix could play a role in improved energy storage capability.

Conducting polymer and its composite materials based electrochemical sensor for Nicotinamide Adenine Dinucleotide (NADH).

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.

Ultrahigh capacitance of amorphous nickel phosphate for asymmetric supercapacitor applications

This article presents the effect of different calcination temperatures on the structural, morphological and capacitance of nickel phosphate (Ni3(PO4)2) as an electrode material for supercapacitor applications. Ni3(PO4)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 Ni3(PO4)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.

Influences Of Sintering Temperatures And Crystallite Sizes On Electrochemical Properties Of LiNiPo4 As Cathode Materials Via Sol–Gel Route For Lithium Ion Batteries

Acetates of lithium (LiC2H3O2) and nickel (NiC2H3O2) together with ammonium dihydrogen phosphate (NH4)H2PO4 were used as starting materials to prepare LiNiPO4 cathode materials via sol–gel technique. This simple and effective method of using distilled water as main solvent was assisted by small amount of oxalic acid. Final product was obtained after sintering process at temperatures of 500u2009°C, 600 u2009°C, 700u2009°C, and 800u2009°C for 3u2009h. The peaks in X-ray diffraction patterns reveal ordered olivine structure of LiNiPO4 under Pnma space group. The surface morphologies as in field emission scanning electron microscopy images clearly showed complete formation of LiNiPO4 with uniform size distribution. Charge–discharge tests recorded initial discharge capacities of 97.3u2009mAhu2009g−1 and 91.1u2009mAhu2009g−1 for LiNiPO4 obtained at sintering temperatures of 700 and 800u2009°C respectively in the voltage range 2.5–4.5u2009V. Insitu carbon coating during synthesis improved electrochemical performances of LiNiPO4. Sintering temperature 700u2009°C produced smaller LiNiPO4 particles compared to 800u2009°C, which enables good capacity retention.Graphical Abstract

An enhanced performance of hybrid supercapacitor based on polyaniline-manganese phosphate binary composite

AbstractManganese phosphate (Mn3(PO4)2) particles decorated polyaniline (PANI) have been proposed as a promising electrode material for supercapacitors. Mn3(PO4)2 particles were synthesized via the sonochemical method followed by calcination. The size of the particles was optimized by varying the sonication times: 30, 60, and 90xa0min which were labeled as M30, M60, and M90. The optimized Mn3(PO4)2 (M90) was blended with presynthesized PANI to form PANI-Mn3(PO4)2 composite (PANI-M90). The phase structure and purity of the synthesized materials were authenticated via X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The morphological studies through field emission scanning electron microscopy (FESEM) showed that M90 particles are firmly anchored on branched-structured PANI which is beneficial for the quick transfer of charges. The electrochemical performance of M30, M60, M90, and PANI-M90 was investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) in 1xa0M KOH electrolyte. PANI-M90 exhibited significantly improved specific capacity (347xa0C/g) than M90 (88xa0C/g) at 1xa0A/g due to the augmentation of redox active sites and the synergistic effect between the conductive PANI and Mn3(PO4)2. Furthermore, the hybrid supercapacitor (activated carbon//PANI-M90) achieved a maximum energy density of 14.7xa0Wh/kg and a power density of 378xa0W/kg with 80% of capacity retention after 3000 charge-discharge cycles.n Graphical abstractGraphical abstract for the morphology and the cyclic voltammogram of M30, M60, M90, and PANI-M90 performed in 1 M KOH

Na-doped LiMnPO4 as an electrode material for enhanced lithium ion batteries

We report the influence of sodium (Na)-incorporated lithium manganese phosphate as an active material on its performance in electrochemical study for energy storage application. Li1−xNaxMnPO4 with different mole ratios (0.00 ≤ x ≤ 0.05) of sodium is synthesized via a simple sol–gel method. The discharge capacity of Li1−xNaxMnPO4 varies with respect to mole ratios of sodium incorporated. The maximum discharge capacity of 92.45 mAh g−1 is observed in Li0.97Na0.03MnPO4, which is higher than that of pristine LiMnPO4 and other Na-incorporated LiMnPO4. The maximum cyclic stability is found to be 84.15% up to 60 cycles. These results demonstrate that Li0.97Na0.03MnPO4 plays a significant role in future energy storage application.

Effect Of Sintering Temperature On Structural Properties Of LiMnPO4 Cathode Materials Obtained By Sol–Gel Method

AbstractnNanostructured LiMnPO4 cathode materials were successfully achieved by sol–gel route with the aid of oxalic acid and nitric acid. The effects of sintering temperatures on structural properties especially strain and crystallite size were analysed. The structural crystallinity and average particle sizes (42–77xa0nm) of LiMnPO4 are significantly varied with respect to calcination temperatures. LiMnPO4 obtained at 700xa0°C exhibits superior electrochemical performance among the samples. It delivered initial discharge capacity of 103.4 mAhxa0g−1 at 0.05xa0C. These results revealed that the sol–gel technique could be favourable method to produce nanosized LiMnPO4 as a cathode material for lithium ion batteries via optimizing calcination temperatures.Graphical Abstract

Scavenging free radicals and soaring osteoinduction by extra cellular matrix protein–based nanocomposites on degenerative bone treatments

A number of materials are now available to alleviate the ever-growing bone disruption. However, these are inadequate and inappropriate for addressing issues associated natural process of aging and degeneration of bone due to diseases. This study advances the existing material and offers more privileged and synergistically active remedy for these conditions. Here, they are three different nano-composites prepared such as nano-TiO2 with chitosan (TC), nano-TiO2 with chondroitin 4-sulfate (TG), and nano-TiO2 with chitosan and chondroitin 4-sulfate (TCG), whereas nano-TiO2 act as a control. The prepared nanocomposite was studied for determining its bactericidal and fungicidal activity by using disk diffusion method. In addition, the osteoinductive, free radical forming, and scavenging abilities of the nanocomposite treated MG-63 cell lines were analyzed using gene expression and biochemical analysis respectively. The augmented fungicidal (~16mm) activities of TCG against bone-infecting pathogens can be effectively used in bone transplantation application. The expression of osteoblast-inducing genes in MG-63 cell line and their up-regulation in nanocomposite treatment, especially in TCG, made this material more desirable. The formation of free radicals such as thiobarbituric acid reactive substance and nitric oxide gradually reduced with the treatment of nanocomposites than control and nano-TiO2. Contrarily, it was found that MG-63 along with nanocomposites statistically increases the production of ALP, antioxidant enzymes (super oxide mutase) and total antioxidant activity (ferric reducing antioxidant power) in several folds compare with the control and nano-TiO2. All the results with statistical scale suggest TCG as an effectual and affordable biomaterial in bone regeneration therapy among the prepared samples.

Enhanced electrochemical properties of ZnO-coated LiMnPO4 cathode materials for lithium ion batteries

We demonstrated the effect of ZnO (different wt%)-coated LiMnPO4-based cathode materials for electrochemical lithium ion batteries. ZnO-coated LiMnPO4 cathode materials were prepared by the sol-gel method. X-ray diffraction (XRD) analysis indicates that there is no change in structure caused by ZnO coating, and field emission scanning electron microscopy (FESEM) images depict the closely packed particles. Galvanostatic charge-discharge tests show the ZnO-coated LiMnPO4 sample has an enhanced electrochemical performance as compared to pristine LiMnPO4. The 2xa0wt% of ZnO-based LiMnPO4 exhibited maximum discharge capacity of 102.2xa0mAhxa0g−1 than pristine LiMnPO4 (86.2xa0mAhxa0g−1) and 1xa0wt% of ZnO-based LiMnPO4 (96.3xa0mAhxa0g−1). The maximum cyclic stability of 96.3xa0% was observed in 2xa0wt% of ZnO-based LiMnPO4 up to 100xa0cycles. This work exhibited a promising way to develop a surface-modified LiMnPO4 using ZnO for enhanced electrochemical performance in device application.