Artificial Photosynthesis for Splitting Water Reaches One-Volt Milestone

ORIGINAL: IEEE Spectrum
By Dexter Johnson
Posted 21 Aug 2013 | 0:53 GMT

Image: HyperSolar

Almost 18 months ago, HyperSolar, Inc., a company based in Santa Barbara, CA, unveiled its ambitious plans for artificial photosynthesis. The announcement promised “the world’s first nanotechnology-based, zero-carbon process for the production of renewable hydrogen and natural gas.” The company was so confident that, two months later, it promised to publicly chronicle its progress toward the lofty goal.

Other companies have tried—and failed—to find an artificial photosynthesis process that can split water into hydrogen and oxygen and do it economically. Around the same time that HyperSolar promised to chronicle their efforts, Sun Catalytix determined that its process for splitting water just didn’t make economic sense when they crunched the numbers.

In the journal Nature, the maker of Sun Catalytix’s prototype explained the dreary economics:

“Hydrogen from a solar panel and electrolysis unit can currently be made for about US$7 per kilogram, the firm estimates; the artificial leaf would come in at US$6.50. (It costs just $1-2 to make a kilogram of hydrogen from fossil fuels.) With the prices of solar cells dropping all the time, the firm is not going to make a heavy investment that's unlikely to pay off. Instead, it is looking at cheaper designs—but these require yet-to-be-invented semiconductor materials.”

When I didn’t hear any updates from HyperSolar on how its grand project was progressing this year, I began to suspect that they had encountered these same numbers and had a second thought. I guess I was wrong—the company just sent out a press release detailing its success in achieving the 1-volt milestone. To date inexpensive silicon solar cells are the most inexpensive and abundant, but their 0.7 volt per cell is not enough to split water.

HyperSolar's 1 volt per cell is still short of the 1.5 volts realistically needed to split water into hydrogen and oxygen, but the 1 volt number does represent a steady progression, according to the company. HyperSolar managed to increase the voltage from 0.2 volts eight months ago to .75 volts three months ago. At that rate of increase, one could expect that the company could achieve the 1.5 volts in another six months.

“Our cutting-edge research program at the University of California Santa Barbara led by Dr. Syed Mubeen Hussaini continues to make impressive progress,” stated Tim Young, CEO of HyperSolar, in the press release. “The 1.0 volt milestone is very exciting in that it provides us with a clear and encouraging roadmap to reach the 1.5 volts needed for water splitting. The semi-conductor materials used are very inexpensive, which gives us confidence that a low cost system is possible. The process to make this novel solar cell is equally exciting in that it is a simple solutions-based chemistry process. It does not require conventional expensive semiconductor processes and facilities. It was literally made in a beaker.”

The key to HyperSolar’s proposed technology will be a nanoparticle made from low-cost semiconductor materials. In the company’s original roadmap for milestones, they were supposed to design this nanoparticle within the first year. It’s not clear from this press release whether that design has been settled upon, except to explain that each nanoparticle: “is a complete hydrogen generator that contains a novel high voltage solar cell bonded to chemical catalysts by a proprietary encapsulation coating.”

It is interesting that the company is providing key metrics for determining whether the system will work, but it would be good to have a better sense of where they are in developing the nanoparticle that forms the basis of this technology.

Chemist Hopes 'Artificial Leaf' Can Power Civilization Using Photosynthesis

ORIGINAL: Yahoo News
By Carrie Halperin
Jun 3, 2013

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Imagine an artificial leaf that mimics photosynthesis, which lets plants harness energy from the sun. But this leaf would have the ability to power your homes and cars with clean energy using only sunlight and water.

This is not some far-off idea of the future. It's reality, and the subject of a jury-prize-winning film in the GE Focus Forward Film Competition.

Jared P. Scott and Kelly Nyks' short film, " The Artificial Leaf," showcases chemist Daniel Nocera, the inventor of the artificial leaf, a device that he says can power the world.

"The truth is stranger than fiction," Kelly Nyks, a partner at PF Pictures, told ABC News. "What I think is so exciting is that Dan has taken this science and applied it in a way that makes bringing it to scale to solve the energy crisis for the planet real and possible."

Nocera's leaf is simply a silicon wafer coated with catalysts that use sunlight to split water to into hydrogen and oxygen components.

"Essentially, it mimics photosynthesis," Nocera told ABC News.

The gases that bubble up from the water can be turned into a fuel to produce electricity in the form of fuel cells. The device may sound like science fiction fantasy, but Nocera said he hopes one day it will provide an alternative to the centralized energy system - the grid.

Worldwide, more than 1.6 billion people live without access to electricity and 2.6 billion people live without access to clean sources of fuel for cooking.

"This is the model: We're going to have a very distributed energy system," Nocera told ABC News. With the leaf, "using just sunlight and water, you can be off the grid. If you're poor, you don't have a grid, so this gives them a way to have energy in the day and at night."

With just the artificial leaf, 1.5 bottles of drinking water and sunlight, you could have enough electricity to power a small home, but the cost is still a problem, though Nocera said he believes that will come down with time and research.

The artificial leaf is cheaper than solar panels but still expensive. Hydrogen from a solar panel and electrolysis unit can currently be made for about $7 per kilogram; the artificial leaf would come in at $6.50.

Nocera is looking for ways to drive down the costs make these devices more widely available. He recently replaced the platinum catalyst that produces hydrogen gas with a less-expensive nickel-molybdenum-zinc compound. He's also looking for ways to reduce the amount of silicon needed.

In 2009, Nocera's artificial leaf was selected as a recipient of funding by the U.S. Department of Energy's Advanced Research Projects Agency (ARPA-E), which supports energy technologies that could create a more secure and affordable American future.

Nyks and Scott said they hope "The Artificial Leaf" will bring awareness to the public that sustainable energy solutions do exist.

"We make films for social action," Scott, also a partner at PF Pictures, told ABC News. "We see films as a tool for social change. And what I think Dan sketches out is that we start with energy. And if we solve the energy crisis, we'll solve the climate crisis, and then we'll solve the water crisis, and then we'll solve the food crisis. But it starts with energy."

30 filmmaking teams were asked to make a movie that could highlight an innovation that could change the world as part of GE Focus Forward, a series of three-minute films created by award-winning documentary makers including Alex Gibney, Lucy Walker, Albert Maysles and Morgan Spurlock. Nyks and Scott won a jury prize in a related global competition.

Dan Nocera, inventor of the artificial leaf.

Anyone with an Internet connection has access to the videos online. All the films are featured at focusforwardfilms.com.

So far, total media impressions for GE Focus Forward have exceeded 1.5 billion. In addition, the films are screening at all the major film festivals around the world and have played on every continent, including Antarctica.

Nyks and Scott said they hope to take the success of the short and turn it into a feature-length documentary. 

Recipe for Low-Cost, Biomass-Derived Catalyst for Hydrogen Production

ORIGINAL: ScienceDaily

Apr. 24, 2013 — In a paper to be published in an upcoming issue of Energy & Environmental Science, researchers at the U.S. Department of Energy's Brookhaven National Laboratory describe details of a low-cost, stable, effective catalyst that could replace costly platinum in the production of hydrogen. The catalyst, made from renewable soybeans and abundant molybdenum metal, produces hydrogen in an environmentally friendly, cost-effective manner, potentially increasing the use of this clean energy source.

The research has already garnered widespread recognition for Shilpa and Shweta Iyer, twin-sister high school students who contributed to the research as part of an internship under the guidance of Brookhaven chemist Wei-Fu Chen, supported by projects led by James Muckerman, Etsuko Fujita, and Kotaro Sasaki.

"This paper reports the 'hard science' from what started as the Iyer twins' research project and has resulted in the best-performing, non-noble-metal-containing hydrogen evolution catalyst yet known -- even better than bulk platinum metal," Muckerman said.

The project branches off from the Brookhaven group's research into using sunlight to develop alternative fuels. Their ultimate goal is to find ways to use solar energy -- either directly or via electricity generated by solar cells -- to convert the end products of hydrocarbon combustion, water and carbon dioxide, back into a carbon-based fuel. Dubbed "artificial photosynthesis," this process mimics how plants convert those same ingredients to energy in the form of sugars. One key step is splitting water, or water electrolysis.

Splitting hydrogen from water: This illustration depicts the synthesis of a new hydrogen-production catalyst from soybean proteins and ammonium molybdate. Mixing and heating the ingredients leads to a solid-state reaction and the formation of nanostructured molybdenum carbide and molybdenum nitride crystals. The hybrid material effectively catalyzes the conversion of liquid water to hydrogen gas while remaining stable in an acidic environment. (Credit: Image courtesy of DOE/Brookhaven National Laboratory)

"By splitting liquid water (H2O) into hydrogen and oxygen, the hydrogen can be regenerated as a gas (H2) and used directly as fuel," Sasaki explained. "We sought to fabricate a commercially viable catalyst from earth-abundant materials for application in water electrolysis, and the outcome is indeed superb."

." ..the best-performing, non-noble-metal-containing hydrogen evolution catalyst yet known..."

This form of hydrogen production could help the scientists achieve their ultimate goal.

"A very promising route to making a carbon-containing fuel is to hydrogenate carbon dioxide (or carbon monoxide) using solar-produced hydrogen," said Fujita, who leads the artificial photosynthesis group in the Brookhaven Chemistry Department.

But with platinum as the main ingredient in the most effective water-splitting catalysts, the process is currently too costly to be economically viable.

Comsewogue High School students Shweta and Shilpa Iyer entered the lab as the search for a cost-effective replacement was on.

The Brookhaven team had already identified some promising leads with experiments demonstrating the potential effectiveness of low-cost molybdenum paired with carbon, as well as the use of nitrogen to confer some resistance to the corrosive, acidic environment required in proton exchange membrane water electrolysis cells. But these two approaches had not yet been tried together.

The students set out to identify plentiful and inexpensive sources of carbon and nitrogen, and test ways to combine them with a molybdenum salt.

"The students became excited about using familiar materials from their everyday lives to meet a real-world energy challenge," Chen recounted. The team tested a wide variety of sources of biomass -- leaves, stems, flowers, seeds, and legumes -- with particular interest in those with high protein content because the amino acids that make up proteins are a rich source of nitrogen. High-protein soybeans turned out to be the best.

To make the catalyst the team ground the soybeans into a powder, mixed the powder with ammonium molybdate in water, then dried and heated the samples in the presence of inert argon gas. "A subsequent high temperature treatment (carburization) induced a reaction between molybdenum and the carbon and nitrogen components of the soybeans to produce molybdenum carbides and molybdenum nitrides," Chen explained. "The process is simple, economical, and environmentally friendly."

Electrochemical tests of the separate ingredients showed that molybdenum carbide is effective for converting H2O to H2, but not stable in acidic solution, while molybdenum nitride is corrosion-resistant but not efficient for hydrogen production. A nanostructured hybrid of these two materials, however, remained active and stable even after 500 hours of testing in a highly acidic environment.

"We attribute the high activity of the molybdenum-soy catalyst (MoSoy) to the synergistic effect between the molybdenum-carbide phase and the molybdenum-nitride phase in the composite material," Chen said.

Structural and chemical studies of the new catalyst conducted at Brookhaven's National Synchrotron Light Source (NSLS) and the Center for Functional Nanomaterials (CFN) are also reported in the paper, and provide further details underlying the high performance of this new catalyst.

"The presence of nitrogen and carbon atoms in the vicinity of the catalytic molybdenum center facilitates the production of hydrogen from water," Muckerman said.

The scientists also tested the MoSoy catalyst anchored on sheets of graphene -- an approach that has proven effective for enhancing catalyst performance in electrochemical devices such as batteries, supercapacitors, fuel cells, and water electrolyzers. Using a high-resolution transmission microscope in Brookhven's Condensed Matter Physics and Materials Science Department, the scientists were able to observe the anchored MoSoy nanocrystals on 2D graphene sheets.

The graphene-anchored MoSoy catalyst surpassed the performance of pure platinum metal. Though not quite as active as commercially available platinum catalysts, the high performance of graphene-anchored MoSoy was extremely encouraging to the scientific team.

"The direct growth of anchored MoSoy nanocrystals on graphene sheets may enhance the formation of strongly coupled hybrid materials with intimate, seamless electron transfer pathways, thus accelerating the electron transfer rate for the chemical desorption of hydrogen from the catalyst, further reducing the energy required for the reaction to take place," Sasaki said.

The scientists are conducting additional studies to gain a deeper understanding of the nature of the interaction at the catalyst-graphene interface, and exploring ways to further improve its performance.

In the paper, the authors -- including the two high-school students -- conclude: "This study unambiguously provides evidence that a cheap and earth-abundant transition metal such as molybdenum can be turned into an active catalyst by the controlled solid-state reaction with soybeans…The preparation of the MoSoy catalyst is simple and can be easily scaled up. Its long-term durability and ultra-low capital cost satisfy the prerequisites for its application in the construction of large-scale devices. These findings thus open up new prospects for combining inexpensive biomass and transition metals…to produce catalysts for electro-catalytic reactions."

Additional collaborators in this research were Chiu-Hui Wang and Yimei Zhu of Brookhaven Lab.

Picking apart photosynthesis

ORIGINAL: RD Magazine

Fri, 03/29/2013

This illustration depicts a metal cluster prepared in the Agapie group on a background of photosystem II, the protein complex that performs photosynthesis in leaves. Image: Emily TsuiChemists at the California Institute of Technology (Caltech) and Lawrence Berkeley National Laboratory believe they can now explain one of the remaining mysteries of photosynthesis, the chemical process by which plants convert sunlight into usable energy and generate the oxygen that we breathe. The finding suggests a new way of approaching the design of catalysts that drive the water-splitting reactions of artificial photosynthesis.

"If we want to make systems that can do artificial photosynthesis, it's important that we understand how the system found in nature functions," says Theodor Agapie, an assistant professor of chemistry at Caltech and principal investigator on a paper in Nature Chemistry that describes the new results.

One of the key pieces of biological machinery that enables photosynthesis is a conglomeration of proteins and pigments known as photosystem II. Within that system lies a small cluster of atoms, called the oxygen-evolving complex, where water molecules are split and molecular oxygen is made. Although this oxygen-producing process has been studied extensively, the role that various parts of the cluster play has remained unclear.

The oxygen-evolving complex performs a reaction that requires the transfer of electrons, making it an example of what is known as a redox, or oxidation-reduction, reaction. The cluster can be described as a "mixed-metal cluster" because in addition to oxygen, it includes two types of metals—one that is redox active, or capable of participating in the transfer of electrons (in this case, manganese), and one that is redox inactive (calcium).

"Since calcium is redox inactive, people have long wondered what role it might play in this cluster," Agapie says.

It has been difficult to solve that mystery in large part because the oxygen-evolving complex is just a cog in the much larger machine that is photosystem II; it is hard to study the smaller piece because there is so much going on with the whole. To get around this, Agapie's graduate student Emily Tsui prepared a series of compounds that are structurally related to the oxygen-evolving complex. She built upon an organic scaffold in a stepwise fashion, first adding three manganese centers and then attaching a fourth metal. By varying that fourth metal to be calcium and then different redox-inactive metals, such as strontium, sodium, yttrium, and zinc, Tsui was able to compare the effects of the metals on the chemical properties of the compound.

"When making mixed-metal clusters, researchers usually mix simple chemical precursors and hope the metals will self-assemble in desired structures," Tsui says. "That makes it hard to control the product. By preparing these clusters in a much more methodical way, we've been able to get just the right structures."

It turns out that the redox-inactive metals affect the way electrons are transferred in such systems. To make molecular oxygen, the manganese atoms must activate the oxygen atoms connected to the metals in the complex. In order to do that, the manganese atoms must first transfer away several electrons. Redox-inactive metals that tug more strongly on the electrons of the oxygen atoms make it more difficult for manganese to do this. But calcium does not draw electrons strongly toward itself. Therefore, it allows the manganese atoms to transfer away electrons and activate the oxygen atoms that go on to make molecular oxygen.

A number of the catalysts that are currently being developed to drive artificial photosynthesis are mixed-metal oxide catalysts. It has again been unclear what role the redox-inactive metals in these mixed catalysts play. The new findings suggest that the redox-inactive metals affect the way the electrons are transferred. "If you pick the right redox-inactive metal, you can tune the reduction potential to bring the reaction to the range where it is favorable," Agapie says. "That means we now have a more rational way of thinking about how to design these sorts of catalysts because we know how much the redox-inactive metal affects the redox chemistry."

Source: California Institute of Technology

Quantum Dots Make Artificial Photosynthesis Last Longer

ORIGINAL: Tech Review

By Kevin Bullis

November 8, 2012

Nanoparticles offer a solution to a key problem with splitting water with sunlight to generate hydrogen.

Why It Matters

Artificial photosynthesis—splitting water with energy from sunlight—could provide a way to harness and store power from the sun and provide carbon-free fuel for cars.

Hydrogen generator: Researchers used this setup to measure hydrogen production facilitated by novel nanoparticles.

Using the energy in sunlight together with water and air to make fuel—artificial photosynthesis—is a little closer thanks to an advance involving nanoscale crystals known as quantum dots.

Researchers have been working on artificial photosynthesis for many years (see “Sun + Water = Fuel”). One approach involves using particles that combine light-absorbing materials with catalysts that can split water. But the light-absorbing materials tend to deteriorate quickly in sunlight, rendering the approach impractical.

In the latest issue of the journal Science, researchers from the University of Rochester show that quantum dots not only absorb the light but also are far more durable than previous light-absorbing materials. The new approach also has the advantage of not requiring any precious metals, so it might be relatively cheap.

The new approach doesn’t solve all of the challenges with artificial photosynthesis. The proof-of-concept system developed by the Rochester team does only half of the water-splitting reaction—that is, it makes hydrogen, but not oxygen. What’s more, particle-based approaches like this one generate both hydrogen and oxygen in one container, and there’s a danger that they will interact and explode. Alternate approaches to photosynthesis that generate hydrogen and oxygen in separate containers are safer.

The remaining difficulties point to the need for efforts like the Department of Energy Innovation Hub at Caltech. The hub is designed to evaluate advances like this one in light of how they might work in a complete artificial photosynthesis system—and if such approaches look workable, to build and test prototype systems (see “Artificial Photosynthesis Effort Takes Root”).

Una iniciativa de fotosíntesis artificial echa raíces

ORIGINAL: Technology Review

Por Kevin Bullis

Traducido por Francisco Reyes (Opinno)

23 de octubre de 2012

Un centro de innovación valorado en 122 millones de dólares (93 millones de euros) podría acelerar el desarrollo de dispositivos para la fabricación de combustible a partir de agua y luz solar.


Al tiempo que se produce un acalorado debate sobre el papel del Gobierno de Estados Unidos en la financiación de la innovación energética, provocado por los prominentes fracasos de compañías con respaldo gubernamental como Solyndra y A123 Systems, una estrategia de inversión federal en tecnología limpia menos controvertida ha estado funcionando a buen ritmo y de forma discreta, consiguiendo un apoyo bipartidista. Los llamados centros de innovación, es decir, centros multidisciplinarios de investigación diseñados para emular los a legendarios Laboratorios Bell mediante la combinación de investigación científica con tecnología aplicada, han logrado obtener financiación continua del Gobierno incluso en una época en la que el Congreso de EE.UU. trabaja para recortar el presupuesto federal total.

Hoja artificial: Este prototipo del Centro Conjunto para la Fotosíntesis Artificial utiliza la energía de la luz solar para aislar el hidrógeno del agua. Fuente: Centro Conjunto para la Fotosíntesis Artificial

Dos años después de obtener financiación por primera vez, uno de los centros actuales, una iniciativa de Caltech (Instituto de Tecnología de California, en EE.UU.) centrada en el uso de luz solar para producir combustibles líquidos, afirma haber conseguido un progreso sustancial hacia dispositivos capaces de convertir la luz del sol y el agua en oxígeno e hidrógeno. Este podría utilizarse para proporcionar energía a un automóvil o generar electricidad de acuerdo a la demanda. Con el tiempo, los investigadores esperan poder combinar el hidrógeno con el carbono del dióxido de carbono para producir combustibles líquidos similares a la gasolina o el diésel.

Los investigadores han estado persiguiendo lo que se conoce como fotosíntesis artificial durante décadas. El progreso ha sido lento, y hacer que el proceso sea económico a gran escala sigue siendo un objetivo aparentemente distante. El nuevo centro de innovación, que recibiría 122 millones de dólares (93 millones de euros) a lo largo de cinco años, planea acelerar esta investigación, reuniendo a un gran número de expertos en diferentes áreas, entre ellas la catálisis, la óptica y la tecnología de membranas.

Para acelerar el descubrimiento de materiales, los investigadores del centro Caltech, que colaboran con investigadores del Laboratorio Nacional Lawrence en Berkeley (EE.UU.) y con más de 20 centros de investigación distintos, han desarrollado un proceso de impresión por chorro de tinta capaz de generar millones de variaciones ligeramente diferentes de prometedores catalizadores. Cada muestra puede llegar a ser tan pequeña como el píxel de una pantalla. También están desarrollando equipos capaces de poner a prueba rápidamente la actividad de cada catalizador. "Acelerará radicalmente el ritmo de descubrimiento de electrocatalizadores y fotocatalizadores para pasar de tener solo algunos candidatos al año a tener varios cada pocos milisegundos, produciendo miles de millones al día", señala Nate Lewis, director del Centro Conjunto para la Fotosíntesis Artificial.

Esquemático de una célula fotoelectroquímica que está siendo diseñada para aprovechar la luz solar para la generación de combustible químico. Una gran cantidad de investigaciones basadas en simulaciones son necesarias para ayudar a comprender, diseñar y fabricar sus componentes. Imagen: NERSC

Al mismo tiempo, el centro ha instalado impresoras avanzadas en 3D capaces de crear prototipos de dispositivos para albergar los materiales absorbentes de luz y los catalizadores, aplicarles agua y separar y recoger el hidrógeno y el oxígeno. Hasta ahora, los investigadores han construido dos prototipos de este tipo capaces de producir combustible a partir de la luz solar, aunque aún no económicamente. El plan es poseer por lo menos cuatro o cinco versiones diferentes de los dispositivos, cada una con distintas fortalezas y debilidades. Los investigadores quieren tener múltiples versiones, ya que no se puede predecir dónde se producirá el siguiente avance en materiales.

La idea de desarrollar nuevas tecnologías energéticas en los centros de innovación es muy diferente del enfoque de ayudar a las empresas a aumentar su producción a través de subvenciones o garantías de préstamo, tal y como hizo el Departamento de Energía de EE.UU. en el caso del A123 y Solyndra. También es muy distinto de financiar proyectos de investigación a través del programa ARPA-E, cuyo objetivo es conseguir avances específicos a un laboratorio o empresa, como el descubrimiento de un nuevo material prometedor, y demostrar su potencial en tres años, por ejemplo, mediante la construcción de una batería funcional con ese material.

Los centros de innovación reúnen a investigadores de diferentes grupos con el objetivo de crear grandes avances para problemas en los que se lleva trabajando desde hace tiempo. Trabajan a muchos niveles diferentes, haciendo de todo, desde descubrir nuevos materiales y estudiar cuidadosamente la forma en que funcionan, así como diseñar y construir dispositivos que podrían utilizar dichos materiales. Mientras ARPA-E otorga subvenciones a cada proyecto valoradas en unos pocos millones de dólares, está previsto que cada centro de innovación reciba más de cien millones de dólares en cinco años como reconocimiento de la gran escala de los problemas que abordan.

Hasta el momento han sido financiados cinco centros, pero la financiación a lo largo de cinco años no está garantizada. El dinero tiene que ser asignado cada año y el presupuesto para el próximo no ha sido aprobado. Aunque los correspondientes comités del Senado y la Cámara de Representantes apoyan la financiación continua durante cinco años, el Congreso se enfrenta a una creciente presión por encontrar partidas donde recortar gastos.