Argonne National Laboratory – A New Membrane Discovery Makes Hydrogen Fuel from Water and Sunlight

Two membrane-bound protein complexes that work together with a synthetic catalyst to produce hydrogen from water. Credit: Olivia Johnson and Lisa Utschig

A chemical reaction pathway central to plant biology have been adapted to form the backbone of a new process that converts water into hydrogen fuel using energy from the sun.

In a recent study from the U.S. Department of Energy’s (DOE) Argonne National Laboratory, scientists have combined two membrane-bound protein complexes to perform a complete conversion of water molecules to hydrogen and oxygen.

The work builds on an earlier study that examined one of these protein complexes, called Photosystem I, a membrane protein that can use energy from light to feed electrons to an inorganic catalyst that makes hydrogen. This part of the reaction, however, represents only half of the overall process needed for hydrogen generation.

By using a second protein complex that uses energy from light to split water and take electrons from it, called Photosystem II, Argonne chemist Lisa Utschig and her colleagues were able to take electrons from water and feed them to Photosystem I.

“The beauty of this design is in its simplicity—you can self-assemble the catalyst with the natural membrane to do the chemistry you want”—Lisa Utschig, Argonne chemist

In an earlier experiment, the researchers provided Photosystem I with electrons from a sacrificial electron donor. “The trick was how to get two electrons to the catalyst in fast succession,” Utschig said.

The two protein complexes are embedded in thylakoid membranes, like those found inside the oxygen-creating chloroplasts in higher plants. “The membrane, which we have taken directly from nature, is essential for pairing the two photosystems,” Utschig said. “It structurally supports both of them simultaneously and provides a direct pathway for inter-protein electron transfer, but doesn’t impede catalyst binding to Photosystem I.”

According to Utschig, the Z-scheme—which is the technical name for the light-triggered electron transport chain of natural photosynthesis that occurs in the thylakoid membrane—and the synthetic catalyst come together quite elegantly. “The beauty of this design is in its simplicity—you can self-assemble the catalyst with the natural membrane to do the chemistry you want,” she said.

One additional improvement involved the substitution of cobalt or nickel-containing catalysts for the expensive platinum catalyst that had been used in the earlier study. The new cobalt or nickel catalysts could dramatically reduce potential costs.

The next step for the research, according to Utschig, involves incorporating the membrane-bound Z-scheme into a living system. “Once we have an in vivo system—one in which the process is happening in a living organism—we will really be able to see the rubber hitting the road in terms of hydrogen production,” she said.

 Explore further: New research sheds light on photosynthesis and creation of solar fuel

More information: Lisa M. Utschig et al, Z-scheme solar water splitting via self-assembly of photosystem I-catalyst hybrids in thylakoid membranes, Chemical Science (2018). DOI: 10.1039/c8sc02841a

Journal reference: Chemical Science  

Provided by: Argonne National Laboratory

 

Cost-effective Production of Hydrogen from Natural Resources

Silicon nanosheets (SiNSs) are one of most exciting recent discoveries. Owing to their unbeatable electro-optical properties and compatibility with existing silicon technology, SiNSs have been the most promising candidate for use in various applications, such as in the process of manufacturing semiconductors and producing hydrogen.

A joint research team, led by Prof. Jae Sung Lee and Prof. Soojin Park of Energy and Chemical Engineering at UNIST, has developed a a cost-effective and scalable technique for synthesizing SiNSs, using natural clay and salt. Through this research, UNIST has taken a major step towards mass production of this ground-breaking material with relatively low cost.

Schematic illustration showing the synthetic process for the preparation of SiNSs.

In their study, published in the current edition of NPG Asia Materials (“All-in-one Synthesis of Mesoporous Silicon Nanosheets from Natural Clay and Their Applicability to Hydrogen Evolution”), the research team reported an all-in-one strategy for the synthesis of high-purity SiNSs through the high-temperature molten salt (for example, NaCl)-induced exfoliation and simultaneous chemical reduction of natural clays.

According to the team, these newly synthesized Si nanosheets are key components in the production of ever smaller electronic devices due to their ultrathin (thickness of ~5 nm) body. Prof. Park states, “As the electrical and electronic devices are getting smaller and smaller, there is a great demand for manufacturing their individual componants to be nanoscale.” He continues, “Our new technique uses inexpensive natural clays and salt for preparing high-quality nanosheets, thereby cutting down production costs greatly.”

As shown in the figure above, in the synthetic process for the preparation of SiNSs, natural clay is exfolicated with molten NaCl. The exfoliated clay is, then, transformed into SiNSs by using Mg reductant. Here, Molten salts can be exchanged with intercalated alkylamines and metal cations inside clays. Then, Mg can reduce the interior of the clay minerals, generating additional heat to induce final exfoliation.

“Through the simultaneous molten-salt-induced exfoliation and chemical reduction of natural clay, both the salt and clay start to melt at a reaction temperature, ranging from 550°C to 700°C. The molten salt is, then, dissolved in the clay layers and disintegrated into individual nanosheets,” said Mr. Jaegeon Ryu, a doctoral researcher in Prof. Soojin Park’s lab and the first author of the study. He continues, “Using the metallothermic reduction, metallic oxides inside clays can be exchanged with silicon.”

The team reports that these nanosheets have a high surface area and contain mesoporous structures derived from the oxygen vacancies in the clay. They add, “These advantages make the nanosheets a highly suitable photocatalyst with an exceptionally high activity for the generation of hydrogen from a water–methanol mixture.”

Source: UNIST

 

Solar Fuels: An’Artificial Leaf’ with Protective Layer for ‘Water Splitting’

The illustration shows the structure of the sample: n-doped silicon layer (black), a thin silicon oxide layer (gray), an intermediate layer (yellow) and finally the protective layer (brown) to which the catalysing particles are applied. The acidic water is shown in green.

Credit: M. Lublow

A team at the HZB Institute for Solar Fuels has developed a process for providing sensitive semiconductors for solar water splitting (“artificial leaves”) with an organic, transparent protective layer. The extremely thin protective layer made of carbon chains is stable, conductive, and covered with catalysing nanoparticles of metal oxides. These accelerate the splitting of water when irradiated by light. The team was able to produce a hybrid silicon-based photoanode structure that evolves oxygen at current densities above 15 mA/cm². The results have now been published in Advanced Energy Materials.

The “artificial leaf” consists in principle of a solar cell that is combined with further functional layers. These act as electrodes and additionally are coated with catalysts. If the complex system of materials is submerged in water and illuminated, it can decompose water molecules. This causes hydrogen to be generated that stores solar energy in chemical form. However, there are still several problems with the current state of technology. For one thing, sufficient light must reach the solar cell in order to create the voltage for water splitting — despite the additional layers of material. Moreover, the semiconductor materials that the solar cells are generally made of are unable to withstand the typical acidic conditions for very long. For this reason, the artificial leaf needs a stable protective layer that must be simultaneously transparent and conductive.

Catalyst used twice

The team worked with samples of silicon, an n-doped semiconductor material that acts as a simple solar cell to produce a voltage when illuminated. Materials scientist Anahita Azarpira, a doctoral student in Dr. Thomas Schedel-Niedrig’s group, prepared these samples in such a way that carbon-hydrogen chains on the surface of the silicon were formed. “As a next step, I deposited nanoparticles of ruthenium dioxide, a catalyst,” Azarpira explains. This resulted in formation of a conductive and stable polymeric layer only three to four nanometres thick. The reactions in the electrochemical prototype cell were extremely complicated and could only be understood now at HZB.

The ruthenium dioxide particles in this new process were being used twice for the first time. In the first place, they provide for the development of an effective organic protective layer. This enables the process for producing protective layers — normally very complicated — to be greatly simplified. Only then does the catalyst do its “normal job” of accelerating the partitioning of water into oxygen and hydrogen.

Organic protection layer combines excellent stability with high current densities

The silicon electrode protected with this layer achieves current densities in excess of 15 mA/cm². This indicates that the protection layer shows good electronic conductivity, which is by no means trivial for an organic layer. In addition, the researchers observed no degradation of the cell — the yield remained constant over the entire 24-hour measurement period. It is remarkable that an entirely different material has been favoured as an organic protective layer: graphene. This two-dimensional material has been the subject of much discussion, yet up to now could only be employed for electrochemical processes with limited success, while the protective layer developed at HZB works quite wel . Because the novel material could lend itself for the deposition process as well as for other applications, we are trying to acquire international protected property rights,” says Thomas Schedel-Niedrig, head of the group.

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Story Source:

The above post is reprinted from materials provided by Helmholtz-Zentrum Berlin für Materialien und Energie. Note: Materials may be edited for content and length.

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Journal Reference:

1. Anahita Azarpira, Thomas Schedel-Niedrig, H.-J. Lewerenz, Michael Lublow. Sustained Water Oxidation by Direct Electrosynthesis of Ultrathin Organic Protection Films on Silicon. Advanced Energy Materials, 2016; DOI: 10.1002/aenm.201502314

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HyperSolar Researcher Wei Cheng to Join University of Iowa Team

A Breakthrough Technology

HyperSolar  (www.hypersolar.com) has developed a breakthrough technology to make renewable hydrogen using sunlight and any source of water. Renewable hydrogen, the cleanest and greenest of all fuels, can be used as direct replacement for traditional hydrogen, which is usually produced by reforming CO2 emitting natural gas.

Inspired By Photosynthesis

By optimizing the science of water electrolysis, our low cost photoelectrochemical process efficiently uses sunlight to separate hydrogen from any source of water to produce clean and environmentally friendly renewable hydrogen. Our innovative solar hydrogen generator eliminates the need for conventional electrolyzers, which are expensive and energy intensive. We believe that our solution will produce the lowest cost renewable hydrogen available in the market today.

The Next Great Renewable Fuel

Hydrogen is the most abundant element and cleanest fuel in the universe. Unlike hydrocarbon fuels, that produce harmful emissions, hydrogen fuel produces pure water as the only byproduct. Using our low cost method to produce renewable hydrogen, we intend to enable a world of distributed hydrogen production for renewable electricity and hydrogen fuel cell vehicles.

Hydrogen expert to join R&D team focused on increasing the water-splitting voltage of proprietary hydrogen technology

SANTA BARBARA, CA – February 18, 2015 –HyperSolar, Inc. (OTCQB: HYSR), the developer of a breakthrough technology to produce renewable hydrogen using sunlight and water, today announced that Dr. Wei Cheng, a post-doctoral researcher who has extensive experience in developing hydrogen production applications and previously served the Company during his time as visiting scholar at the University of California, Santa Barbara, will be joining HyperSolar’s research and development team at the University of Iowa.

Dr. Cheng focuses on developing a low-cost way to make photo-electrochemical devices for producing hydrogen in wastewater. Dr. Cheng received his bachelor’s degree in Materials Science and Technology from Nanjing University of Aeronautics and Astronautics, his master’s degree and PhD in Materials Physics and Chemistry from Shanghai Jiao Tong University, China. He is currently a post-doctoral researcher at the University of Iowa. His previous works include producing hydrogen using low voltage electro-oxidation of organic wastewater and preparing non-toxic metal sulfide semiconductors with low-cost materials such as tin monosulfide (SnS) and Cu2ZnSnS4.

As HyperSolar’s technology progresses, the market for hydrogen fuel continues to build momentum. Just recently, the “big 3” auto manufacturers in Japan – Nissan, Toyota, and Honda – jointly announced their goal of “working together to help accelerate the development of hydrogen station infrastructure for fuel cell vehicles (FCVs).” Among several topics, hydrogen fuel infrastructure with respect to fueling stations was emphasized throughout the announcement as being of utmost importance. HyperSolar believes that its hydrogen producing technology, which uses a completely renewable process capable of being implemented at or near the point of distribution, will support fueling infrastructure upon commercialization.

“We are thrilled that Dr. Cheng will be joining our University of Iowa team to focus on increasing the water-splitting voltage required for commercialization of real-world systems,” said Tim Young, CEO of HyperSolar. “Dr. Cheng’s background in producing hydrogen, along with his familiarity with HyperSolar technology, makes him an integral part of our research and development team. As hydrogen fuel solutions continue to garner attention from major corporations around the world, we are confident that our technology will serve many applications within both consumer and commercial industries.”

HyperSolar’s technology is based on the concept of developing a low-cost, submersible hydrogen production particle that can split water molecules using sunlight without any other external systems or resources – acting as artificial photosynthesis. A video of an early proof-of-concept prototype can be viewed at http://hypersolar.com/application.php.

Date: Wednesday, February 18, 2015

Could hydrogen vehicles take over as the “green” car of choice?

Now that car makers have demonstrated through hybrid vehicle success that consumers want less-polluting tailpipes, they are shifting even greener. In 2015, Toyota will roll out the first hydrogen fuel-cell car for personal use that emits only water. An article in Chemical & Engineering News (C&EN), the weekly newsmagazine of the American Chemical Society, explains how hydrogen could supplant hybrid and electric car technology — and someday, even spur the demise of the gasoline engine.

Melody M. Bomgardner, a senior editor at C&EN, notes that the first fuel-cell vehicles will be sold in Japan, then California to start. Although Toyota is the only one poised to sell fuel-cell vehicles very soon, other companies are also investing billions of dollars in the technology. Hyundai, General Motors, Honda and Daimler have all announced plans to offer their own hydrogen models in the near future. The first cars will set customers back about $70,000, but this marks a 95 percent cut in system costs in less than 10 years. As they improve the technology further, car manufacturers expect that prices will come down to more affordable levels.

In 2015, Toyota will be the first car maker to bring a personal, hydrogen fuel-cell vehicle to the market.

Credit: Toyota            

 But does that translate into a practical edge for consumers? With a hydrogen vehicle, filling up only takes about three minutes, compared to an overnight charge for an all-electric car. Fuel-cell vehicles can go 400 miles on one fill-up, which is fewer than a hybrid but with no polluting emissions. Although electrics also boast zero tailpipe emissions, they will have a tough time competing with that kind of range. Given these advantages, some experts suggest hydrogen fuel cells could someday overtake hybrid, electric and even internal combustion technologies.

                  

Source: American Chemical Society