Li-Ion Rechargeable Batteries
Li-Ion (Lithium-Ion) batteries are the most common rechargeable batteries in portable electronics. Lithium ion batteries have one of the best energy densities, no memory effect,  slow loss of charge when not in use and environmentally safe because there is no free lithium metal, in comparison with other types of rechargeable batteries. Rechargeable lithium ion batteries are the preferred compact light weight storage media of choice to store a large amount of energy in a small space. They provide power for electric cars, electric bicycles, smart phones and laptops. Globally researchers are currently in the process of developing new generation of such batteries with an improved performance. In most lithium ion batteries these days, the plus pole is composed of the transition metal oxides cobalt, nickel, and manganese, the minus pole of graphite. In more powerful lithium ion batteries of the next generation, however, elements such as tin or silicon may well be used at the minus pole.
Nanomaterial based lithium ion batteries
Researchers from the Laboratory of Inorganic Chemistry at ETH Zurich and Empa have now developed a nanomaterial based lithium ion batteries.
Structure
The nanomaterial has tiny tin crystals as the battery anode. During charging lithium ions get absorbed at this electrode and released again while discharging. With more lithium ions the electrodes can absorb and release and hence more energy can be stored in the battery. Here each tin atom can absorb at least four lithium ions, but change in volume. In the tin electrodes tin crystals become up to three times bigger by absorbing a lot of lithium ions and shrinks again when it releases them back which is a challenge to the researchers. If the electrode were made of a compact tin block, this would practically be impossible. To overcome this drawback researchers use nanotechnology to produce the tiniest and uniform tin nanocrystals and embed a large number of them in a porous, conductive permeable carbon matrix.
During the development of the nanomaterial with ideal size and uniformity the researchers follow two steps during formation of small crystal nucleus and its subsequent growth by influencing the time and temperature of the growth phase.
Future development
With the choice of the best possible carbon matrix and binding agent for the electrodes, and an ideal microscopic structure for electrodes along with an optimal and stable electrolyte liquid in which the lithium ions can travel back and forth between the two poles the researcher believe that cost-effective base materials suitable for electrode production with increased energy storage capacity and lifespan can be produced.

Plasmons are free electrons on the surface of metals that become excited by the input of energy, typically from light. Moving plasmons can transform optical energy into heat. 

Plasmonic nanoparticles are particles whose electron density can couple with electromagnetic radiation of wavelengths that are far larger than the particle. This is due to the nature of the dielectric-metal interface between the medium and the particles unlike in a pure metal where there is a maximum limit on what size wavelength can be effectively coupled based on the material size. Plasmonic nanoparticles also exhibit interesting scattering, absorbance, and coupling properties based on their geometries and relative positions. These unique properties have made them a focus of research in many applications including solar cells, spectroscopy, signal enhancement for imaging, and cancer treatment.
Plasmonic gold nanoparticles
Gold nanoparticles can be used for efficiently converting energy because of their optical absorbance is about a million times higher than any other molecules in nature. Rice University scientists have shown that common gold nanoparticles, known as gold colloids, heat up at near-infrared wavelengths as narrow as a few nanometers when hit by very short pulses of laser light.
The effect reported appears to be related to nonstationary optical excitation of plasmonic nanoparticles. Plasmonic gold nanoparticles make pinpoint heating on demand possible. Researchers have found a way to selectively heat diverse nanoparticles that could advance their use in medicine and industry.
The above particles traditionally respond to wide spectra of light, and not much of it is in the valuable near-infrared region. Near-infrared light is invisible to water and, more critically for biological applications, to tissue. According to researchers all nanoparticles, beginning with solid gold colloids and moving to more sophisticated, engineered gold nanoshells, nanorods, cages and stars, have very wide spectra, typically about 100 nanometers and hence only one type of nanoparticle can be used at a time.
The discovery allowed researchers to use controlled laser pulses to tune the absorbance spectrum of plain gold colloids. The Rice lab showed basic colloidal gold nanoparticles could be efficiently activated by a short laser pulse at 780 nanometers, with an 88-fold amplification of the photothermal effect seen with a continuous laser.

Nanoparticles of silicon can be made to react instantly with water to produce hydrogen without application of any heat, light or electricity.

Hydrogen production

Traditional techniques to split water to produce hydrogen include electrolysis, thermolysis and photo catalysis.But bulk silicon abundantly available on earth can react slowly with water to produce hydrogen by releasing two moles of hydrogen gas per mole of silicon without releasing any carbon dioxide.

Nanosilicon

Silicon nanoparticles due to their high surface to volume ratio can generate hydrogen quickly than bulk silicon due to high reaction rate. Researchers at the University at Buffalo (SUNY) in New York have developed this technique.

For example nanoparticles 10 nm in size can produce hydrogen in under a minute which is1000 times faster at producing hydrogen than is bulk silicon and nanoparticles of 100 nm in diameter can produce at 45 minutes.

During the hydrogen production reaction, the 10 nm silicon particles reduce in size, but do not change shape, where as the 100 nm particles do not uniformly reduce in size, but form hollow shells or capsules with walls of a few monolayers of silicon which then slow down the water-silicon reaction due to the formation of an extra layer through which the reactants must diffuse.

Applications

According to the researchers this technology can be used for powering small portable devices and might even replace bulky gasoline or diesel generators in the future and a typical silicon generator could comprise a small hydrogen fuel cell and some plastic cartridges of silicon nanopowder, to which water would be added when needed, to produce energy.

The overall efficiency of hydrogen production could be quite competitive with primary batteries and other sources of portable power.

Nanoballoons

Also hollow nanoballoons can be produced by reaction of the larger silicon particles by mixing with other materials such as alkali hydrides to make anodes for lithium-ion batteries. Alkali metal hydrides react with water to release hydrogen and produce alkali metal hydroxides like sodium hydroxide needed to catalyse the silicon reaction with water by making them stable due to silicon nanoparticles coating.

Nanoshells, nanoeggs and nanocups. 

Nanoshells, consist of a spherical silica core coated with a thin gold shell and can be converted to nanoeggs by offsetting the core within the shell. When the offset of the core is greater than the thickness of the shell layer, the core pierces the shell, resulting in nanocups. Nanoeggs exhibit absorption and scattering spectra with multipolar peaks strongly red shifted relative to those of nanoshells and larger near-field enhancements. Researchers at the Hong Kong University of Science and Technology have developed a nanoegg with a hard cobalt shell surrounding a core of platinum and iron and found that it could safely deliver platinum, a known anticancer agent, to tumor cells. Nanoegg has been found to be seven times more toxic than the anticancer agent cisplatin to cancer cells. Synthesis of cobalt sulfide nanoparticles forms a hollow shell structure in the presence of nanoparticles made of iron and platinum and the resulting structures have a porous crystalline shell of cobalt sulfide surrounding nanocrystals of iron/platinum. The pores in the outer shell are large enough for water to access the interior of the nanoparticle. But hollow cobalt sulfide nanoparticles are not toxic to cultured human cancer cells.  
Nanocups 

Nanocups are very tiny, cup-shaped particles which can bend light. Researchers have found a way to make material incorporating nanocups that can bend light in a specific direction and no light bounces off the metamaterial back making the material invisible, Researchers have embedded nanocups which are the first true three-dimensional nano-antennas, and their light-bending properties are made possible by plasmons. 

Making nanocups 

To make light-bending material, polystyrene or latex colloidal particles are spread on a glass slide, layer of gold is evaporated at various angles on top of the particles, a layer of elastomer is deposited on top, cure and the slab is lifted from the substrate with the oriented nanocups embedded. 
Applications 

Nanocup metamaterial can transmit optical signals between computer chips; can be used to make enhanced spectroscopy and super lenses and to track the sun in a solar panel to focuses light into a beam that's always on target. 

Other shapes 

Ghim Wei Ho of the University of Cambridge Nanoscale Science Laboratory claims that we can grow nanowires, cones, rings, cups, flowers etc. Apart from their beauty as three-dimensional structures, detailed characterisation reveals a complex mixture of amorphous and crystalline material which not only determines the ultimate structure but also provides a unique material with potential applications for both electronic and photonic devices.

Photosynthesis
Photosynthesis is the process of converting solar radiation into green energy to produce sugar, which cellular respiration converts into ATP by the plants, bacteria and some protistans green using green chlorophyll pigment using water and releasing oxygen.
Artificial photosynthesis
Artificial photosynthesis systems exploiting light-absorbing molecules or chromophores, typically made of organic dyes, to photo chemically split water into hydrogen and oxygen by half-reactions with reduction and oxidation process. But the light-absorbing dyes are damaged due to Sun's rays and the process is inefficient and unstable.
Researchers at the University of Rochester, USA have generated hydrogen using nanocrystals, sunlight and a cheap nickel catalyst which can continuously produce fuel without slowing down.
Nanocrystals
Nanocrystals have fewer defects due to their limited size . nanocrystals have very little interior volume and are virtually all surface and the inner impurities can easily migrate the short distance to the surface and be ejected by doping. Doping is the addition of impurities containing electrons to enable electric conductance in a controlled way. The physical properties of these crystals are determined by the interface between the core and the shell.
On the nanoscale doping could lead to an assortment of technologies, including solar cells, light-emitting diodes, lasers or displays, electroluminescent devices and electronic devices.
The system
Artificial photochemical hydrogen-generating system contains cadmium selenide quantum dots, nickel salt catalysts and ascorbic acid. The system when working with water has a quantum efficiency of 36% for every 100 photons absorbed and produces 36 hydrogen molecules. For a solution of a mix of water and ethanol the efficiency increases to 66%. The ascorbic acid acts as an electron donor, gets used up and regularly needs to be replenished during each hydrogen production cycle.
Working
The researchers explain that CdSe quantum dots absorb two photons of light and transfer two electrons to the Ni-catalyst allowing it to take up two protons to produce hydrogen by forming the necessary catalyst locally from the quantum dot ligands. The catalyst-nanocrystal pairs are better than other artificial photosynthesis nanoparticle systems because they are more stable to sunlight.
Applications
The finding could be very important for green-energy applications and also for certain industrial processes like those for producing ammonia in the Haber process.

Carbon nanotubes
Carbon nanotubes (CNTs) have high strength and modulus, high electrical and thermal conductivities, are stable at relatively high and low temperatures. Individual nanotubes can be 100 times stronger than steel.
To effectively exploit the exceptional properties of individual nanotube’s in various applications, continuous pure CNT yarns and high CNT content composite yarns need to be fabricated.
MWCNTs reinforced PAN fibers and CNT/cellulosic continuous bamboo yarns can be used to manufacture CNTs filled multifunctional products by electro spinning. This process can give significant improvements of the mechanical, thermal and electrical properties of the yarn by incorporation of CNT into the nanofibers. SWCNT fibers can also be manufactured from liquid crystal solutions to get continuous neat CNT fibers.
Making CNT yarn
A continuous CNT fiber yarn using multiple threads of high purity double walled carbon nanotubes can be fabricated in a horizontal CVD gas flow reactor with water vapor densification by the spinning process. Water vapor is used for obtaining homogeneous shrinking of the CNT sock-like assembly with dense thread of thickness 1–3 mm and highly porous structure (99%) with mechanically strong and electrically conductive properties. The CNT yarn can have well controlled continuous winding.  The yarn can be infiltrated with polymers to form a composite and mixed with other yarns to form a blend to be used for various CNT based structural and functional applications.
Artificial muscles made of CNT
Carbon nanotubes can be used to construct artificial muscles as CNTs can be made into yarns which are seamless, hollow cylinders made from the graphite layers.
Researchers claim that the artificial muscles developed by them can provide large, ultra fast contractions to lift weights that are 200 times heavier than possible for a natural muscle of the same size. But at present the artificial muscle is unsuitable for directly replacing muscles in the human body.
Making CNT muscles
The artificial muscles are made by infiltrating a volume-changing paraffin wax into twisted yarn made of carbon nanotubes. Heating the wax-filled yarn, either electrically or using a flash of light, causes the wax to expand, the yarn volume to increase, and the yarn length to contract.
The volume increase of yarn and decrease of length results because of the helical structure produced by twisting the yarn.
Applications of muscles
These yarn muscles are simple and have high performance and muscle contraction or actuation can be ultra fast, occurring in 25-thousandths of a second for both actuation and reversal. They can be used for diverse applications in robots, catheters for minimally invasive surgery, micro motors, and mixers for micro fluidic circuits, tunable optical systems, micro valves, positioners and even toys.
Carbon Nanotube Sheets
There are difficulties in assembling the trillions of nanotubes into macro-sized objects without the use of binders. This aspect has retarded the growth of practical applications.
By simultaneously rotating carbon nanotubes in vertically oriented nanotube arrays (forests) wide and long transparent sheets can be formed. These self-supporting nanotube sheets are initially formed as a highly anisotropic electronically conducting aero gel that can be densified into strong thin sheets. These nanotube sheets have been used for the microwave bonding of plastics and for making transparent, highly elastomeric electrodes; planar sources of polarized broad-band radiation; conducting appliqués; and flexible organic light-emitting diodes.

Folding the DNA

DNA nanotechnology which is like paper folding was developed around 30 years back. In 2006, Paul Rothemund of the California Institute of Technology demonstrated folding long strands of DNA into a wide range of predetermined shapes. The resulting nanostructures can be used as scaffolding or as miniature circuit boards for precisely assembling components such as carbon nanotubes and nanowires.

But to make DNA  structure of several folds, several hundred "staples" must be added to the regions surrounding the single DNA strands, and for making new nanostructures a new set of staples are requires. Moreover, the DNA structures tend to arrange themselves randomly onto a substrate surface making it difficult to integrate them into electronic circuits subsequently.

DNA brick

To overcome the above difficulty researchers at Harvard University in the US have developed a technique to make highly complex 3D nanostructures by assembling together synthetic DNA "bricks". The bricks, which are like tiny pieces of LEGO, can be assembled into a wide variety of shapes and configurations to build elaborately designed nanostructures. Researchers made DNA-bricks by self-assembly technique starting with long DNA strands by interlocking short, synthetic strands of DNA together to make larger structures by suitably controlling the local interactions between the strands. The technique relies on DNA self-assembly method using the four base pairs in DNA – adenosine, thymine, cytosine and guanine which can naturally join in specific ways to fabricate a collection of 2D structures.

Technique

The technique to make 3D structure starts with a smaller DNA-brick strand of only 32 bases long having four regions to bind to four neighbouring DNA-brick strands which are connected through 90° and built in space for creating a DNA molecular cube containing hundreds of bricks. Each DNA structure self-assembles to a brick encoded with an individual sequence that determines its final position in the nanostructure. Each sequence will only be attracted to a complementary sequence so that specific shapes can be created through the selection of different sequences.

Applications

Using DNA-brick technique any number of structures can be made very easily from the same master cube by simply selecting subsets of specific DNA bricks. Many complex shapes can be made containing intricate cavities, surface features and channels which are more complex than any 3D DNA structure constructed so far. Also modifications can be made by adding or removing DNA bricks without changing the main structure. The researchers claim that many appropriate technologically relevant guest molecules can be incorporated into functional devices that might serve as programmable molecular probes, instruments for biological imaging and drug-delivery vehicles and to fabricate high-throughput complex inorganic devices for electronics and photonics applications. They further claim that by using synthetic polymers rather than the natural form of DNA, it may be possible to create functional structures that are stable in a wider variety of different environments. The researchers say that the structures made using DNA-brick technique might find use in a wide variety of applications such as in smart medical devices for targeted drug delivery in the body, programmable imaging probes and even in the manufacture of speedier and more powerful computer-chip circuits.

DNA microchip

Microchips are used in computers, cell phones and other electronic devices. IBM is building DNA microchips using DNA nanostructures. This is an effort for using biological molecules to help with processing in the semiconductor industry, because biological structures like DNA actually offer some very reproducible, repetitive kinds of patterns. It will be the structure of next-generation and chipmakers are competing to develop smallest chips at cheaper price.

Gene detection

A gene detection platform made from self-assembled DNA nanostructures has been made using 100 trillion reactive and functional DNA components. By scanning attached differentiated labels on mass a clear reading of the molecular composition of a solution can be obtained. This method will allow for the bar coding of individual molecules for easy identification and analysis.

Bio sensing

Investigation of US researchers has resulted in nanostructures made entirely out of graphene and DNA. When the interactions between the two components were tracked using a fluorescent protein it was found that single-stranded DNA interacts with the carbon compound much stronger than its double-stranded sibling.

When complementary DNA was added to strands already on grapheme, the marker protein started glowing with renewed strength, indicating that new DNA molecules were formed, as the first strands separated from their graphene substrate. According to the researchers, this property could pave the way to creating new classes of biosensors.

Graphene-DNA nanostructures will be used in hospitals for detecting conditions such as cancer, toxins in decaying and altered food and also to scan packages suspected of carrying biological weapons for any traces of pathogens.

DNA machines

Oxford Centre for Soft and Biological Matter reports that the elegant selectivity of Watson-Crick base-pairing makes DNA an extremely useful tool for the construction of nanoscale objects and machines. Stable structures and mechanical cycles can be programmed into a system of single strands by careful choice of the sequences of bases.

DNA nanostructure scaffold

Researchers at Arizona State University have developed various shapes and sizes of DNA nanostructure which can carry molecules to trigger an immune response in the body. They have already developed DNA nanostructures which could function as scaffolding material and created synthetic vaccine complexes resembling natural virus without the disease component. Synthetic vaccine complexes were then attached to DNA nanostructures of pyramid shape and branch-like structures. This holds great potential for the development of targeted therapeutics.

DNA crystals

New York University chemists have created three-dimensional DNA structures which have a range of potential industrial and pharmaceutical applications, such as the creation of nanoelectronic components and the organization of drug receptor targets to enable illumination of their 3D structures.

The researchers created DNA crystals by making synthetic sequences of DNA that have the ability to self-assemble into a series of 3D triangle-like motifs. The creation of the crystals was dependent on putting "sticky ends"—small cohesive sequences on each end of the motif—that attach to other molecules and place them in a set order and orientation. The make-up of these sticky ends allows the motifs to attach to each other in a programmed fashion. By using genetic engineering technique multiple helices were linked together through single-stranded sticky ends lattice-like structures were formed that extends in six different directions, thereby yielding a 3D crystal.

Nanorods
nanorods are one morphology of nanoscale objects with dimensions ranging from 1–100 nm. produced by direct chemical synthesis from metals or semiconducting materials. A combination of ligands acts as shape control agents bonding to different facets of the nanorod growing at different rates to produce elongated objects with desired strengths. The nanorods find application in MEMS, in energy harvesting and light emitting devices, as tunable photoluminescence and particularly in display technologies due to property that the reflectivity of the rods can be changed by changing their orientation with an applied electric field.
To make a new generation of optical devices such as light filters, sensors and other applications it is desirable to have a property by which it can be easily tuned with the interaction of light.
Web-like structure
Researchers at the Laboratory for Photonics and Nanostructures in Marcoussis, France have shown that a web-like structure made up of an array of evenly spaced nanorods can to block almost 100% of a specific light wavelength. The photonic nanoweb consists of transparent freestanding dielectric silicon nitride nanorods around 500 nm thick covering only 15% of the surface area and lined up in a single layer of rows 3 µm apart. The researchers found that the two dimensional array can allow a broad range of light wavelengths to pass through it but light that has a wavelength of exactly 3.2 µm of infrared range cannot pass through and is almost totally reflected due to a change in the  optical response in a very narrow spectral range. But light with a wavelength of 3 µm is transmitted through the web while that at 3.2 µm sharply drops.
Principle
The nanoweb resembles a very sparse diffraction grating and behaves more like a crystal with the rods acting like a monolayer of atoms that multiply scatter light. The incident light is first scattered by each nanorod and then some of this scattered light impinges on the other nanorods and is scattered again due to which a constructive interference of light waves build up from this multiple scattering process in the plane of the scatterers and, finally, the sum of the scattered light is emitted in both the forward and backward directions.
In the forward direction, the light waves scattered by the rods and transmitted through the rods are cancelled out by destructive interference, leading to perfect optical extinction and complete light reflection.
No Bragg diffraction
In the nanoweb almost all photons interact with the scatterers in a single lattice plane, where as in Bragg diffraction the constructive interference involves a large number of planes.
Until now, research on nanostructures that interact strongly with light in this way was confined to metallic nanostructures, such as gold nanoparticles, in which collective oscillations of surface electrons (or so-called surface plasmon resonances) strongly absorb or scatter light. The new study shows that these strong interactions can also be produced by a periodic arrangement of freestanding dielectric structures, like silicon nitride nanorods.
Applications
It can be used to make a new generation of optical devices, including light filters, sensors and light-sensing applications. The finding will result in a structure resembling a type of diffraction grating made of nanorods regularly ordered in a 2D array that would perfectly reflect light of a specific wavelength.

For the morphological control of nanostructures during bottom-up growth several techniques are used.
GLAD
Glancing angle deposition (GLAD) is a technique that uses a flow of atoms from gas phase to impinge on a substrate surface under an oblique angle. Physical vapor deposition under conditions of obliquely incident flux and limited atom diffusion results in a film with a columnar microstructure. These columns will be oriented toward the vapor source and substrate rotation can be used to sculpt the columns into various morphologies.
Glancing angle deposition (GLAD) is an advanced bottom-up nanostructuring technique developed by Michael Brett’s group at the University of Alberta, Canada. GLAD provides precision engineering of nanostructures via control over macroscopic geometry during deposition.
Deposition modulation allows for real-time fabrication of previously unachievable hybrid architectures during bottom-up growth. For example, with modulation of deposition rate and substrate orientation during growth, branches can be placed on selected regions of the trunk, and the trunk diameter can be controlled.
GLAD on flat substrates involves a nucleation process yielding layers of distributed columns. Periodic arrays of columns can be grown by patterning the substrate with seed particles prior to deposition. Here the patterned sites will function as nucleation sites for the columns since the shadowing effect will suppress growth on the surrounding substrate.
Columnar structure formation
The origin of the columnar structure characteristic of GLAD films can be discussed in terms of nucleation processes and structure zone models.
As deposition continues, the columnar structures are influenced by atomic-scale ballistic shadowing and surface diffusion. Competitive growth is observed where the tallest columns grow at the expense of smaller features. The column shape evolves during growth, and power-law scaling behavior is observed as shown in both experimental results and theoretical simulations. Due to the porous nature of the films and the increased surface area, a variety of chemical applications and sensor device architectures are possible. Because the GLAD process provides precise nanoscale control over the film structure, characteristics such as the mechanical, magnetic, and optical properties of the deposited film may be engineered for various applications. Depositing onto prepatterned substrates forces the columns to adopt a planar ordering, an important requirement for photonic crystal applications.
VLS-GLAD
GLAD technique can be combined with vapour liquid solid (VLS) to grow indium tin oxide (ITO) nanowhiskers. This technique named VLS-GLAD allows advanced control over ITO nanowhisker morphology and enables the researchers to tailor bulk optical and electrical properties of ITO nanowhisker films.
The ITO nanowhisker structure resembles a tree, with branches like a trunk growing orthogonal to the primary growth direction. VLS-GLAD technique enables control over number density, diameter and branching of ITO nanowhiskers and provides ability to scientists to shape the branch architecture. ITO nanowhiskers find application in high surface area electrodes, gas sensors, protein molecule sensors and UV light sources.
Applications
The VLS-GLAD technique can improve the control over the morphology of nanowhiskers and the ability to fabricate hybridized nanostructures from the bottom-up. The method for nanostructuring of materials is applied in the fabrication of photovoltaics and fuel cells, sensor and analytical devices utilizing porous materials, and nanoscale chiral thin films for photonics and photonic crystals.