Batteries Included: A Solar Cell that Stores its Own Power

Batteries Included: A Solar Cell that Stores its Own Power

World’s first “solar battery” runs on light and air

By: Pam Frost Gorder

Published on October 03, 2014

COLUMBUS, Ohio—Is it a solar cell? Or a rechargeable battery?

Actually, the patent-pending device invented at The Ohio State University is both: the world’s first solar battery.

In the October 3, 2014 issue of the journal Nature Communications, the researchers report that they’ve succeeded in combining a battery and a solar cell into one hybrid device.

Key to the innovation is a mesh solar panel, which allows air to enter the battery, and a special process for transferring electrons between the solar panel and the battery electrode. Inside the device, light and oxygen enable different parts of the chemical reactions that charge the battery.

Yiying Wu

The university will license the solar battery to industry, where Yiying Wu, professor of chemistry and biochemistry at Ohio State, says it will help tame the costs of renewable energy.

“The state of the art is to use a solar panel to capture the light, and then use a cheap battery to store the energy,” Wu said. “We’ve integrated both functions into one device. Any time you can do that, you reduce cost.”

He and his students believe that their device brings down costs by 25 percent.

The invention also solves a longstanding problem in solar energy efficiency, by eliminating the loss of electricity that normally occurs when electrons have to travel between a solar cell and an external battery. Typically, only 80 percent of electrons emerging from a solar cell make it into a battery.

With this new design, light is converted to electrons inside the battery, so nearly 100 percent of the electrons are saved.

The design takes some cues from a battery previously developed by Wu and doctoral student Xiaodi Ren. They invented a high-efficiency air-powered battery that discharges by chemically reacting potassium with oxygen. The design won the $100,000 clean energy prize from the U.S. Department of Energy in 2014, and the researchers formed a technology spinoff called KAir Energy Systems, LLC to develop it.

“Basically, it’s a breathing battery,” Wu said. “It breathes in air when it discharges, and breathes out when it charges.”

For this new study, the researchers wanted to combine a solar panel with a battery similar to the KAir. The challenge was that solar cells are normally made of solid semiconductor panels, which would block air from entering the battery.

Doctoral student Mingzhe Yu designed a permeable mesh solar panel from titanium gauze, a flexible fabric upon which he grew vertical rods of titanium dioxide like blades of grass. Air passes freely through the gauze while the rods capture sunlight.

Normally, connecting a solar cell to a battery would require the use of four electrodes, the researchers explained. Their hybrid design uses only three.

The mesh solar panel forms the first electrode. Beneath, the researchers placed a thin sheet of porous carbon (the second electrode) and a lithium plate (the third electrode). Between the electrodes, they sandwiched layers of electrolyte to carry electrons back and forth.

Here’s how the solar battery works: during charging, light hits the mesh solar panel and creates electrons. Inside the battery, electrons are involved in the chemical decomposition of lithium peroxide into lithium ions and oxygen. The oxygen is released into the air, and the lithium ions are stored in the battery as lithium metal after capturing the electrons.

When the battery discharges, it chemically consumes oxygen from the air to re-form the lithium peroxide.

An iodide additive in the electrolyte acts as a “shuttle” that carries electrons, and transports them between the battery electrode and the mesh solar panel. The use of the additive represents a distinct approach on improving the battery performance and efficiency, the team said.

The mesh belongs to a class of devices called dye-sensitized solar cells, because the researchers used a red dye to tune the wavelength of light it captures.

In tests, they charged and discharged the battery repeatedly, while doctoral student Lu Ma used X-ray photoelectron spectroscopy to analyze how well the electrode materials survived—an indication of battery life.

First they used a ruthenium compound as the red dye, but since the dye was consumed in the light capture, the battery ran out of dye after eight hours of charging and discharging—too short a lifetime. So they turned to a dark red semiconductor that wouldn’t be consumed: hematite, or iron oxide—more commonly called rust.

Coating the mesh with rust enabled the battery to charge from sunlight while retaining its red color. Based on early tests, Wu and his team think that the solar battery’s lifetime will be comparable to rechargeable batteries already on the market.

The U.S. Department of Energy funds this project, which will continue as the researchers explore ways to enhance the solar battery’s performance with new materials.

Related images

• 
  Researchers at The Ohio State University have invented a solar battery -- a combination solar cell and battery -- which recharges itself using air and light. The design required a solar panel which captured light, but admitted air to the battery. Here, scanning electron microscope images show the solution: nanometer-sized rods of titanium dioxide (larger image) which cover the surface of a piece of titanium gauze (inset). The holes in the gauze are approximately 200 micrometers across, allowing air to enter the battery while the rods gather light. Image courtesy of Yiying Wu, The Ohio State University. - Download

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http://news.osu.edu/news/2014/10/03/batteries-included-a-solar-cell-that-stores-its-own-power/

Pilots Blinded by Solar Panels in Southern California

Sunday, 20 Jul 2014 08:42 AM

By Elliot Jager

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Intense glare from California's Ivanpah Solar Electric Generating System in San Bernardino County could be endangering air traffic between Los Angeles and Las Vegas, Breitbart  reported.

A July 17 study by the Sandia National Laboratories indicated that mirrored heliostats, used to generate solar energy at the 397-megawatt power plant, causes glare when the panels are in "standby" mode, according to KCET.

The federal lab report, "Evaluation of Glare at the Ivanpah Solar Electric Generating System," indicated that when the heliostats are aimed directly at the sky, not at the boilers, they "can cause visual afterimages for observers as distant as six miles from the power plant."

Raising the danger of midair collisions, pilots have complained that glare from the mirrors was making it difficult to look out for other nearby aircraft, KCET reported.

Experienced pilots have described the glare as unusually bright and widespread, according to Breitbart.

There are some 120 weekly commercial flights between McCarran Airport outside Las Vegas and Los Angeles-area airports in addition to private air traffic, KCET reported.

In response to inquiries from the Las Vegas airport authorities, Energy Services which owns Ivanpah wrote that as more of the panels are calibrated and repositioned the glare should be lessened.

The California Energy Commission is expected to hold hearing in Blythe, Ca. between July 29-31 on the even bigger Palen Solar Electric Generating System in Riverside County  which now awaiting regulatory approval.

Related Stories:

• Rooftop Solar Panels Become Growing Threat to Firefighters
  
• Al Gore: 'Cheaper' Solar Power Helping to Save the Planet

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New material could provide massive boost to solar cell efficiency

New material could provide massive boost to solar cell efficiency

• By Joel Hruska on June 23, 2014 at 3:25 pm
• 1 Comment

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A group of scientists working with the University of Utah believe they’ve discovered a method of substantially boosting solar cell efficiencies, in a breakhrough that could significantly reduce the total cost per watt — if it can be successfully commercialized.

Traditionally, solar cell technology has struggled to overcome a significant efficiency problem. The type of substrate used dictates how much energy can be absorbed from sunlight — but each type of substrate (silicon, gallium arsenide, indium gallium arsenide, and many others) corresponds to capturing a particular wavelength of energy. Cheap solar cells built on inexpensive silicon have a maximum theoretical efficiency of 34% and a practical (real-world) efficiency of around 22%. Multijunction cells that use multiple substrates to capture a larger section of the sun’s spectrum can reach up to 87% efficiency in theory, but are currently limited to 43% in practice. What’s more, these types of multijunction cells are extremely expensive — wiring and laying out precise structures is far more difficult than a simple thin film silicon cell.

We have a vast array of cells, but all of the inexpensive, common designs are low-efficiency. Image courtesy of Wikipedia

What the team has developed is a polychromat layer that separates and sorts incoming light, redirecting it to strike particular layers in a multijunction cell. The test device used two layers — indium gallium phosphide (for visible light) and gallium arsenide for infrared light. According to the research team, “When the University of Utah polychromat was added, the power efficiency increased by 16 percent.” The team also ran simulations of a polychromat layer with up to eight different absorbtion layers and claim that it could yield an efficiency increase of up to 50%, but have not actually tested the technology.

The polychromat layer sits on top and splits energy wavelengths, aiming them at the layers where they’ll be absorbed.

This is where the reporting gets a little tenuous. The University of Utah statement refers to single-junction solar panels but describes a multi-junction device. Furthermore, it states the gain as a percentage rather than “percentage points.” This implies that the sentence should be understood as a percent of a percent; if the original cell efficiency was, say, 30%, then a gain of 16% percent means that the new efficiency is 34.8% (30 percent * 1.16x). That’s still a huge gain for a polychromat layer that the researchers say could be stamped out using DVD-like technology, but it’s not quite the enormous advance it’s been depicted as.

Given that the biggest barrier to III-V multi-junction solar cell technology is manufacturing complexity and associated cost, anything that boosts cell efficiency on the front end without requiring any major changes to the manufacturing process is going to help with the long-term commercialization of the technology. Until now, most of the multijunction devices deployed go into space or are used by for military applications where cost is less of an issue and peak performance is essential. Advances like this could help make technologies cost effective for personal deployment and allow them to scale in a similar fashion to cheaper devices.

http://www.extremetech.com/extreme/184977-new-material-could-provide-massive-boost-to-solar-cell-efficiency 

Four-junction, four-terminal stacked solar cell hits 43.9 percent efficiency

Four-junction, four-terminal stacked solar cell hits 43.9 percent efficiency

By Darren Quick
April 30, 2014

3 Pictures

Arrays of stacked multi-junction cells achieving ultra high efficiencies were produced using a printing-based assembly process
Image Gallery (3 images)

The ultimate goal of solar cell technology is to be able to generate electricity at costs lower than sources such as coal, natural gas and nuclear. Key to this is continuing improvements in conversion efficiency, and with the development of the first four-junction, four-terminal stacked solar cell produced using a micro transfer printing process, researchers have taken another step towards this goal by achieving efficiencies of up to 43.9 percent, with the possibility of exceeding 50 percent in the near future.
The multilayer, microscale solar cell was created by North Carolina-based Semprius Inc. and California-based Solar Junction, working in collaboration with a team from the University of Illinois at Urbana-Champaign led by Professor John Rogers. Using Semprius' proprietary high-speed micro transfer printing process high that it says is able to simultaneously produce thousands of stacked microcells with very high yields, the team stacked a triple-junction microcell on top of a single-junction microcell to create a four-junction, four-terminal stacked solar cell.
The team says the use of four junctions allows the stacked cell to capture a broader range of the solar spectrum, while the use of four terminals rather than the standard two increases the yield of the solar cell under normal operation in the field. Additionally, a new interfacial material that is placed between the top and bottom cells helps to optimize overall efficiency by minimizing optical losses within the stack.

The triple-junction solar cell is covered in an anti-reflective coating to ensure efficient transmission of light to the uppermost layers, while the bottom cell is a single-junction germanium microcell. Light with wavelengths between 300 and 1,300 nm is captured by the triple-junction cell, while light with wavelengths from 1,300 to 1,700 nm passes through to the germanium cell. The result is a multilayer, microscale solar cell that the team says outperforms conventional silicon and single-junction solar cell in terms of efficiency.
"The strategy involves high-speed, printing-based manipulation of thin, microscale solar cells and new interface materials to bond them into multilayer stacks,” Rogers said. "Quadruple-junction, four-terminal solar cells that we can build in this way have individually measured efficiencies of 43.9 percent."
However, Semprius, which was co-founded by Rogers in 2006 to commercialize ultrahigh efficiency photovoltaic modules, promises that the same process will be capable of achieving efficiencies exceeding 50 percent in the near future.
Like the 44.4 percent efficiency record reported by Sharp last year, the 43.9 percent efficiency figure was achieved using a lens system to concentrate light onto the solar cells. Using a dual-stage optics system, the incident sunlight was focused more than 1,000 times. Modules created from the microscale solar cells also achieved efficiencies of 36.5 percent under the same conditions.
"This is very nice work," stated Ali Javey, a professor of electrical engineering and computer sciences at the University of California, Berkeley, who wasn't involved in the research. "The results are impressive, and the schemes appear to provide a route to ultra-high efficiency photovoltaics, with strong potential for utility-scale power generation."
Rogers is first author of a paper detailing the new solar cell that is published this week in the journal Nature Materials.
Sources: Semprius, University of Illinois at Urbana-Champaign

http://www.gizmag.com/four-junction-four-terminal-stacked-solar-cell/31868/

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Scientists Discover How to Generate Solar Power in the Dark

Meet 'photoswitches,' a breakthrough set of materials that act as their own batteries, absorbing energy and releasing it on demand.

Todd Woody Apr 15 2014, 1:27 PM ET

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Andres Gutierrez/AP

The next big thing in solar energy could be microscopic.
Scientists at MIT and Harvard University have devised a way to store solar energy in molecules that can then be tapped to heat homes, water or used for cooking.

The best part: The molecules can store the heat forever and be endlessly re-used while emitting absolutely no greenhouse gases.  Scientists remain a way’s off in building this perpetual heat machine but they have succeeded in the laboratory at demonstrating the viability of the phenomenon called photoswitching.

An Atlantic Special Report
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“Some molecules, known as photoswitches, can assume either of two different shapes, as if they had a hinge in the middle,” MIT researchers said in statement about the paper published in the journal Nature Chemistry. “Exposing them to sunlight causes them to absorb energy and jump from one configuration to the other, which is then stable for long periods of time.”

To liberate that energy all you have to do is expose the molecules to a small amount of light, heat or electricity and when they switch back to the other shape the emit heat. “In effect, they behave as rechargeable thermal batteries: taking in energy from the sun, storing it indefinitely, and then releasing it on demand,” the scientists said.

The researchers used a photoswitching substance called an azobenzene, attaching the molecules to substrates of carbon nanotubes. The challenge: Packing the molecules closely enough together to achieve a sufficient energy density to generate usable heat.

It appeared that the researchers had failed when they were only able to pack fewer than half the number of molecules needed as indicated by an earlier computer simulation of the experiment.

But instead of hitting a projected 30 percent increase in energy density, they saw a 200 percent increase. It turned out that the key was not so much packing azobenzene molecules tightly on individual carbon nanotubes as packing the nanotubes close together. That’s because the azobenzene molecules formed “teeth” on the carbon nanotubes, which interlocked with teeth on adjacent nanotubes. The result was the mass needed for a usable amount of energy storage.

That means different combinations of photoswitching molecules and substrates might achieve the same or greater energy storage, according to the researchers.

So how would molecular solar storage work if the technology can be commercialized? Timothy Kucharski, the paper’s lead author and a postdoc at MIT and Harvard, told The Atlantic that most likely the storage would take a liquid form, which would be easy to transport.

“It would also enable charging by flowing the material from a storage tank through a window or clear tube exposed to the sun and then to another storage tank, where the material would remain until it's needed,” Kucharski said in an email.  “That way one could stockpile the charged material for use when the sun's not shining.”

The paper’s authors envision the technology could be used in countries where most people rely on burning wood or dung for cooking, which creates dangerous levels of indoor air pollution, leads to deforestation and contributes to climate change.

“For solar cooking, one would leave the device out in the sun during the day,” says Kucharski. “One design we have for such an application is purely gravity driven – the material flows from one tank to another. The flow rate is restricted so that it's exposed to the sun long enough that it gets fully charged. Then, when it's time to cook dinner, after the sun is down, the flow direction is reversed, again driven by gravity, and the opposite side of the setup is used as the cooking surface.”

“As the material flows back to the first tank, it passes by an immobilized catalyst which triggers the energy-releasing process, heating the cooking surface up,” he adds.

Other versions of such device could be used to heat buildings.
Kucharski said the MIT and Harvard team is now investigating other photoswitching molecules and substrates, “with the aim of designing a system that absorbs more of the sun's energy and also can be more practically scaled up.”

 http://www.theatlantic.com/technology/archive/2014/04/scientists-discover-how-to-generate-solar-power-in-the-dark/360679/

Scientists discover material that can be solar cell by day, light panel by night

http://phys.org/news/2014-03-scientists-material-solar-cell-day.html

This solar cell is developed from Perovskite, a promising material that could hold the key to creating high-efficiency, inexpensive solar cells. The new cells not only glow when electricity passes through them, but they can also be customised to emit different colours.
Picture this: A shopping mall facade could be storing solar energy in the day and transforms into a light display for advertisements that glows at night.
This discovery, published in top academic journal Nature Materials, was discovered almost by chance when NTU physicist Sum Tze Chien, asked his postdoctoral researcher Xing Guichuan to shine a laser on the new hybrid Perovskite solar cell material they are developing.


Read more at: http://phys.org/news/2014-03-scientists-material-solar-cell-day.html#jCp

This solar cell is developed from Perovskite, a promising material that could hold the key to creating high-efficiency, inexpensive solar cells. The new cells not only glow when electricity passes through them, but they can also be customised to emit different colours.
Picture this: A shopping mall facade could be storing solar energy in the day and transforms into a light display for advertisements that glows at night.
This discovery, published in top academic journal Nature Materials, was discovered almost by chance when NTU physicist Sum Tze Chien, asked his postdoctoral researcher Xing Guichuan to shine a laser on the new hybrid Perovskite solar cell material they are developing.


Read more at: http://phys.org/news/2014-03-scientists-material-solar-cell-day.html#jCp

This solar cell is developed from Perovskite, a promising material that could hold the key to creating high-efficiency, inexpensive solar cells. The new cells not only glow when electricity passes through them, but they can also be customised to emit different colours.
Picture this: A shopping mall facade could be storing solar energy in the day and transforms into a light display for advertisements that glows at night.
This discovery, published in top academic journal Nature Materials, was discovered almost by chance when NTU physicist Sum Tze Chien, asked his postdoctoral researcher Xing Guichuan to shine a laser on the new hybrid Perovskite solar cell material they are developing.


Read more at: http://phys.org/news/2014-03-scientists-material-solar-cell-day.html#jCp

In the future, when your mobile or tablet runs out of battery, you could just recharge it by putting it out in the sun. Nanyang Technological University (NTU) scientists have developed a next-generation solar cell material which can also emit light, in addition to converting light to electricity.

Read more at: http://phys.org/news/2014-03-scientists-material-solar-cell-day.html#jCp

A CIGS Photovoltaic Sub-Module With Conversion Efficiency Of 18.34 Percent

By putting together the formation technology for high quality light absorption layers and the advanced integration technology that had been developed at an earlier stage, the researchers achieved for the first time a high conversion efficiency, over 18 percent, of a CIGS photovoltaic sub-module. The developed technology is a core elemental technology for the improvement of the conversion efficiency of photovoltaic modules and is applicable to a wide variety of photovoltaic modules including large-area modules and flexible modules. This technology is expected to contribute to the improvement of the conversion efficiency of mass-produced photovoltaic modules, a reduction in power generation costs, and improvements in the functionality of photovoltaic modules.

http://www.photonicsonline.com/doc/a-cigs-photovoltaic-sub-module-with-conversion-efficiency-of-percent-0001

News | November 19, 2013

New Study Could Lead To Paradigm Shift In Organic Solar Cell Research

Organic solar cells have long been touted as lightweight, low-cost alternatives to rigid solar panels made of silicon. Dramatic improvements in the efficiency of organic photovoltaics have been made in recent years, yet the fundamental question of how these devices convert sunlight into electricity is still hotly debated.

Now a Stanford University research team is weighing in on the controversy. Their findings, published in the Nov. 17 issue of the journal Nature Materials, indicate that the predominant working theory is incorrect, and could steer future efforts to design materials that boost the performance of organic cells.
"We know that organic photovoltaics are very good," said study coauthor Michael McGehee, a professor of materials science and engineering at Stanford. "The question is, why are they so good? The answer is controversial."
A typical organic solar cell consists of two semiconducting layers made of plastic polymers and other flexible materials. The cell generates electricity by absorbing particles of light, or photons.
When the cell absorbs light, a photon knocks out an electron in a polymer atom, leaving behind an empty space, which scientists refer to as a hole. The electron and the hole immediately form a bonded pair called an exciton. The exciton splits, allowing the electron to move independently to a hole created by another absorbed photon. This continuous movement of electrons from hole to hole produces an electric current.
In the study, the Stanford team addressed a long-standing debate over what causes the exciton to split.
"To generate a current, you have to separate the electron and the hole," said senior author Alberto Salleo, an associate professor of materials science and engineering at Stanford. "That requires two different semiconducting materials. If the electron is attracted to material B more than material A, it drops into material B. In theory, the electron should remain bound to the hole even after it drops.
"The fundamental question that's been around a long time is, how does this bound state split?"
Some like it hot
One explanation widely accepted by scientists is known as the "hot exciton effect." The idea is that the electron carries extra energy when it drops from material A to material B. That added energy gives the excited ("hot") electron enough velocity to escape from the hole.
But that hypothesis did not stand up to experimental tests, according to the Stanford team.
"In our study, we found that the hot exciton effect does not exist," Salleo said. "We measured optical emissions from the semiconducting materials and found that extra energy is not required to split an exciton."
So what actually causes electron-hole pairs to separate?
"We haven't really answered that question yet," Salleo said. "We have a few hints. We think that the disordered arrangement of the plastic polymers in the semiconductor might help the electron get away."
In a recent study, Salleo discovered that disorder at the molecular level actually improves the performance of semiconducting polymers in solar cells. By focusing on the inherent disorder of plastic polymers, researchers could design new materials that draw electrons away from the solar cell interface where the two semiconducting layers meet, he said.
"In organic solar cells, the interface is always more disordered than the area further away," Salleo explained. "That creates a natural gradient that sucks the electron from the disordered regions into the ordered regions. "
Improving energy efficiency
The solar cells used in the experiment have an energy-conversion efficiency of about 9 percent. The Stanford team hopes to improve that performance by designing semiconductors that take advantage of the interplay between order and disorder.
"To make a better organic solar cell, people have been looking for materials that would give you a stronger hot exciton effect," Salleo said. "They should instead try to figure out how the electron gets away without it being hot. This idea is pretty controversial. It's a fundamental shift in the way people think about photocurrent generation."

SOURCE: Stanford University

http://www.photonicsonline.com/doc/new-study-could-lead-to-paradigm-shift-in-organic-solar-cell-research-0001

Color This New Solar Cell Efficiency Breakthrough Blue

The holy grail of our research is not necessarily to boost efficiencies as high as they can theoretically go, but rather to combine increases in efficiency to the kind of large-scale roll-to-roll printing or processing technologies that will help us drive down costs.
Read more at http://cleantechnica.com/2014/01/25/new-solar-cell-efficiency-breakthrough-harvests-blue-light/#jfhq1j5Du6HoudUH.99

http://cleantechnica.com/2014/01/25/new-solar-cell-efficiency-breakthrough-harvests-blue-light/

The thin film angle is important to solar cell affordability because, although thin film is not as efficient as the gold standard (that would be silicon), it is far more inexpensive to manufacture and it has a greater range of applications.
Read more at http://cleantechnica.com/2014/01/25/new-solar-cell-efficiency-breakthrough-harvests-blue-light/#jfhq1j5Du6HoudUH.99

The thin film angle is important to solar cell affordability because, although thin film is not as efficient as the gold standard (that would be silicon), it is far more inexpensive to manufacture and it has a greater range of applications.
The new Argonne solar cell research pivots on the manufacturing process to harvest more light from the blue end of the spectrum.

Read more at http://cleantechnica.com/2014/01/25/new-solar-cell-efficiency-breakthrough-harvests-blue-light/#jfhq1j5Du6HoudUH.99

The thin film angle is important to solar cell affordability because, although thin film is not as efficient as the gold standard (that would be silicon), it is far more inexpensive to manufacture and it has a greater range of applications.
The new Argonne solar cell research pivots on the manufacturing process to harvest more light from the blue end of the spectrum.

Read more at http://cleantechnica.com/2014/01/25/new-solar-cell-efficiency-breakthrough-harvests-blue-light/#jfhq1j5Du6HoudUH.99

Triangle researchers find possible solution to solar energy problem

By Jay Price

jprice@newsobserver.comJanuary 14, 2014 Updated 3 hours ago

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CHAPEL HILL — A team of researchers led by a UNC-Chapel Hill chemistry professor has discovered a potential solution to one of the fundamental problems of generating large amounts of energy from the sun’s rays: how to store some of the power so it’s available at night.
The scientists, who also include researchers from N.C. State University, found a new way to use solar energy to split molecules of water into its atomic-level components: oxygen and hydrogen. The hydrogen can then be burned for fuel, generating only water as waste, which can then be recycled to be split again.
The hydrogen could be created and used by infrastructure similar to generators and solar arrays that are already familiar, said Tom Meyer, director of the federally funded Energy Frontier Research Center at UNC-CH, who led the research.
“Part of a solar array, instead of just making electricity during the day, could in fact be making chemicals,” he said. “So when the sun goes down, you just run the chemicals through your power plant, and you extract the energy back out as you need it.”
Only a fraction of the energy being generated in the U.S. now comes from solar or from wind, which also is intermittent. But it’s enough to already create some distribution problems, and the issue is expected to increase as more renewable energy sources are added to the national grid.
Meyer had been researching how to turn solar energy into fuels for several decades while also working on other projects, he said. Parts of the process had long been apparent, but it took the addition of nanoparticle engineering to capitalize on the potential.
That’s where Gregory Parsons’ group at N.C. State University came in, said Meyer. Parsons is director of NCSU’s Nanotechnology Initiative.
The process uses two basic components. One, a molecule called a chromophore-catalyst assembly, absorbs sunlight and then begins breaking down the water molecules. The other, a nanoparticle to which thousands of chromophore-catalyst assemblies are attached, is part of a film that shuttles away electrons, a vital part of deconstructing the water molecules.
It didn’t work smoothly, though, until Meyer turned to Parsons’ team, which found a method for coating the nanoparticles with extremely thin layers of titanium dioxide. The scientists found that the nanoparticles could then carry away electrons quickly enough to make the process work well. They also figured out how to build a protective coating that keeps the chromophore-catalyst assembly tethered firmly to the nanoparticle, as the two pieces had tended to break apart.
More efficiency expected
The process currently generates hydrogen equal to about 1 percent of the energy in the sunlight received. But now that it’s clear the concept works, the researchers think there’s little doubt that they can improve the efficiency, Meyer said. They hope to reach their goal of at least 15 percent, which is similar to the efficiency of current commercial solar cells.
Also, they plan to explore the potential for using the same process to turn the greenhouse gas carbon dioxide into a carbon-based fuel such as methanol that could be burned in a closed loop, generating carbon dioxide to be used again.

Price: 919-829-4526

Read more here: http://www.newsobserver.com/2014/01/14/3532549/triangle-researchers-find-possible.html#storylink=cpy