Supercapacitors have drawn considerable attention in recent years due to their high specific power, long cycle life, and ability to bridge the power/energy gap between conventional capacitors and batteries/fuel cells. Nanostructured electrode materials have demonstrated superior electrochemical properties in producing high-performance supercapacitors. In this review article, we describe the recent progress and advances in designing nanostructured supercapacitor electrode materials based on various dimensions ranging from zero to three. We highlight the effect of nanostructures on the properties of supercapacitors including specific capacitance, rate capability and cycle stability, which may serve as a guideline for the next generation of supercapacitor electrode design.

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Supercapacitor electrode materials: nanostructures from 0 to 3 dimensions

Synthesis and effect of silver nanoparticles on the antibacterial activity of different antibiotics against Staphylococcus aureus and Escherichia coli.

Metal-organic molecular architectures with 2,2′-bipyridyl-like and carboxylate ligands

The world is recently witnessing an explosive development of novel electronic and optoelectronic devices that demand more-reliable power sources that combine higher energy density and longer-term durability. Supercapacitors have become one of the most promising energy-storage systems, as they present multifold advantages of high power density, fast charging-discharging, and long cyclic stability. However, the intrinsically low energy density inherent to traditional supercapacitors severely limits their widespread applications, triggering researchers to explore new types of supercapacitors with improved performance. Asymmetric supercapacitors (ASCs) assembled using two dissimilar electrode materials offer a distinct advantage of wide operational voltage window, and thereby significantly enhance the energy density. Recent progress made in the field of ASCs is critically reviewed, with the main focus on an extensive survey of the materials developed for ASC electrodes, as well as covering the progress made in the fabrication of ASC devices over the last few decades. Current challenges and a future outlook of the field of ASCs are also discussed.

Asymmetric Supercapacitor Electrodes and Devices.

Green synthesis of silver nanoparticles using latex of jatropha curcas

Silver nanoclusters embedded in glass matrices have been obtained by the combined use of ion exchange and subsequent ion implantation. XRD and UV-visible spectro-photometric analysis have confirmed the formation of Ag nano-clusters in the ion-irradiated samples. Temperature-dependent resistivity measurements of the irradiated samples have been found to follow ρ ( T )∝exp√( T 0 / T ) in the temperature range of 80–280 K. The observed behaviour of ρ ( T ) is consistent with charge transport due to hopping between isolated, conducting islands. The separation distance between the conducting islands has been found to be a function of fluence.

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Electrical transport studies of Ag nanoclusters embedded in glass matrix

Results obtained from the optical absorption and photoluminescence (PL) spectroscopy experiments have shown the formation of excitons in the silver-exchanged glass samples. These findings are reported here for the first time. Further, we investigate the dramatic changes in the photoemission properties of the silver-exchanged glass samples as a function of postannealing temperature. Observed changes are thought to be due to the structural rearrangements of silver and oxygen bonding during the heat treatments of the glass matrix. In fact, photoelectron spectroscopy does reveal these chemical transformations of silver-exchanged soda glass samples caused by the thermal effects of annealing in a high vacuum atmosphere. An important correlation between temperature-induced changes of the PL intensity and thermal growth of the silver nanoparticles has been established in this Letter through precise spectroscopic studies.

Optical Absorption and Photoluminescence Spectroscopy of the Growth of Silver Nanoparticles

The last few decades have witnessed a tremendous increase in the interest to use ferrofluids and ferrofluid-drug conjugates in magnetically guided drug delivery in loco regional treatment of cancer/tumor. In this paper, experiments on iron oxide (maghemite, /spl gamma/-Fe/sub 2/O/sub 3/)-gold superparamagnetic core-shell nanoparticles conjugated to human serum albumin-drug complex are presented. Coating these nanoparticles with gold varies the shell thickness resulting in particles with overall diameter from 15 to 30 nm thus pushing the gold shell plasmon resonance to 700 - 800 nm region . This in turn makes these particles suitable for use in laser induced hyperthermia. These core shell particles were also coated with serum albumin proteins to make them more resistant to auto immune response. When coated with bovine or human serum albumin, these particles can be further complexed with drugs such as emodin, quercetin dihydrate (anti-cancer) and anti-inflammatory ibuprofen. Since both tumor and inflammatory tissues are known to have slightly acidic pH, unlike healthy tissues, it is shown that on changing the pH from 8 to 6.4, the native form of drugs can be released from the composite particles in situ, thus ensuring drug delivery on target.

Novel superparamagnetic core-shell nanoparticles for magnetic targeted drug delivery and hyperthermia treatment

The crystallization solvent exerts a critical control of the nonlinear optical properties of helical superstructures in molecular crystals based on N,N'-bis(4-nitrophenyl)-(1R,2R)-diaminocyclohexane. While crystallization from ethyl acetate resulted in mutually orthogonal helices with different handedness, crystallization from ethyl acetate/hexane or acetyl acetone/hexane resulted in the formation of helical motifs of a single-handedness oriented in one direction. The latter showed a strong solid-state second harmonic generation capability.

Helical Superstructures of a C2‐Symmetric Molecule Exhibiting Strong Second Harmonic Generation in the Solid‐State

The plasmonic effect of gold nanoparticles (AuNPs) enhances light absorption and, thus, the efficiency of organic bulk heterojunction solar cells with poly (3-hexylthiophene) (P3HT): [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as active layer. We report optimization of this enhancement by varying the attachment density of the self-assembled AuNPs on silanized ITO using N1-(3-trimethoxysilylpropyl)diethylenetriamine. Using finite difference time domain simulations, the thicknesses of poly (3,4-ethylenedioxythiophene) (PEDOT): poly (styrenesulfonate) (PSS) and P3HT:PCBM layers were suitably varied to ensure broadband optical absorption enhancement and minimal exciton quenching within the active layer. Our experimental results demonstrate that for solar cell structures with 20% surface coverage, absorption is increased by 65% as predicted by simulations. Further, we show that AuNPs increase the efficiency by 30% and that silanization of ITO positively impacts device performance.

Palash Gangopadhyay

Papers

Electrical transport studies of Ag nanoclusters embedded in glass matrix

Optical Absorption and Photoluminescence Spectroscopy of the Growth of Silver Nanoparticles

Novel superparamagnetic core-shell nanoparticles for magnetic targeted drug delivery and hyperthermia treatment

Helical Superstructures of a C2‐Symmetric Molecule Exhibiting Strong Second Harmonic Generation in the Solid‐State

Ultrathin organic bulk heterojunction solar cells: Plasmon enhanced performance using Au nanoparticles