Energy generation - Page 6

Researchers from Taiwan's Institute of Atomic and Molecular Sciences developed a light-activated switch by coating graphene with chlorophyll. This is a simple photon transistor - two silver electrodes, connected by a sheet of graphene which is covered by a layer of chlorophyll (using drop casting).

When the chlorophyll is exposed to light it releases electrons into the graphene. Chlorophyll is very efficient - each photon that it absorbs increases the current by about a million electrons. The device that the researchers made is very basic and will need a lot of work before it can be commercialized.

Researchers from Manchester University and the National University of Singapore developed a new, efficient and sensitive solar cell made from sheets of graphene and transition metal dichalcogenides (TMDC). The TMDC (also a 2D material) sheets are very efficient light absorbers while the graphene is used as a transparent conductive layer.

The researchers are optimistic that more and more photoactive "heterestructures" such as the one developed now can be achieved, which will allow them to design multi-functional materials with new functionalities (for example color changing).

Researchers from the DOE's Brookhaven National Laboratory developed a new catalyst (made from Graphene, molybdenum and soybeans) and that could replace platinum in hyroden-production processes. This new catalyst is the best non-noble-metal one ever developed, and it's even better than a catalyst made from bulk platinum. It can be used to split water into hydrogen and oxygen. The hydrogen can then be used regenerated into H2 and then be used as fuel.

To make the new catalyst, the researchers ground soybeans into a powder and then mixed it it with ammonium molybdate. Using a high-temperature carburization made the molybdenum react with the carbon and nitrogen in the soybean and that produced molybdenum carbides and molybdenum nitrides. The material was then anchored on sheets of graphene - and this makes the catalyst effecting in devices such as batteries, supercapacitors, fuel cells, and water electrolyzers.

Researchers from University of Exeter have developed a new flexible, transparent and ultra-lightweight photodetector device made from graphene and graphExeter (a room-temperature transparent conductor discovered at the University of Exeter in 2012). The new device can also be used to generate electricity. It's only a few atoms thick and can be woven into textiles to create photovoltaic fabrics.

The researchers say that the efficiency of the new device is similar to opaque devices based on graphene and metals (Nokia, for example, is working on graphene-based photo detectors). The new device does not contain any metals. It can detect light across the entire visible light spectrum.

Researchers from the Indian Institute of Technology (in Delhi, India) have shown that layers of graphene deposited on silicon have excellent anti reflection properties. The researchers demonstrated (using theoretical calculations and experiments) that CVD-deposited graphene is much better as a UV anti-reflectance layer compared to the commonly used Si3N4 layer used in current solar-cells.

Earlier this month we reported on a new research (from Peking University) showing that Titanium Dioxide can be used as a anti-reflective layer in graphene-silicon solar cells to make them more efficient.

Researchers from Peking University discovered that graphene-silicon solar cells can be made more efficient by coating it with an anti-reflective layer (they used Titanium Dioxide).

The researchers say that normal silicon solar cells have an efficiency of about 15%. Adding graphene (as an electrode and also as the charge-carrying layer) can make the cells cheaper, but these are less efficient (at 8.6%). Coating the graphene-silicon structure with a 65-nm-thick layer of titanium dioxide decreases the reflected light from over 30% to less than 10%, which means that more light is converted to electricity - and the efficiency of these new cells is 14.6%.

Researchers from Columbia University say that the electronic properties of graphene are very sensitive to the local environment. Using scanning tunneling microscopy, the researcher studied graphene films exfoliated onto cleaved mica (an ultra flat material that contains surface electric dipoles).

It turns out that graphene remains undoped immediately above the water molecules but becomes p-doped on the mica surface surrounding them. On the other hand, graphene becomes n-doped near the potassium ion regions. There are two types of n-doping in graphene: immediately above the potassium plateau there is a lot more electron doping then areas on flat regions.

Researchers from the ICFO, MIT, Max Planck and Graphenea have demonstrated that graphene is able to concert a single photon into several electrons (most materials generate a single electron in such a case). This means that Graphene is highly efficient in converting light to energy and can be an alternative material for light detection and energy harvesting.

The researchers used a single sheet of graphene and sent a known number of photos with different colors (energies). High energy photos (violet colored for examples) create more electrons than low energy photos (such as infrared colored ones).

Bluestone Global Tech released two short videos introducing Graphene. The first focuses on the different graphene properties (strength, flexibility, conductivity, etc):

The second video is all about the different graphene applications, such as displays, LEDs, touch screens, batteries, solar cells and conductive wires

Update: read more about Duke's graphene-based artifical muscles research here

Researchers from Duke University are developing ways to control the crumpling and unfolding of large area graphene. By attaching the graphene to a pre-stretched rubber film. When the film was relaxed, parts of the graphene sheet detached, forming an attached-detached pattern with a feature size of a few nanometers. When the film was stretched again, the adhered spots of graphene pulled on the crumpled areas to unfold the sheet.

So basically stretching and relaxing a rubber film, even manually can crumple and unfold large area graphene sheets. This opens up the possibility of all sorts of applications. One example is a graphene film that can be changed from transparent to opaque (it is transparent when stretched but opaque when crumpled).