It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Saturday, November 26, 2022
525-million-year-old fossil defies textbook explanation for brain evolution
According to a new study, fossils of a tiny sea creature with a delicately preserved nervous system solve a century-old debate over how the brain evolved in arthropods, the most species-rich group in the animal kingdom
IMAGE: ARTIST'S IMPRESSION OF AN INDIVIDUAL 525-MILLION-YEAR-OLD CARDIODICTYON CATENULUM ON THE SHALLOW COASTAL SEA FLOOR, EMERGING FROM THE SHELTER OF A SMALL STROMATOLITE BUILT BY PHOTOSYNTHETIC BACTERIA.view more
CREDIT: NICHOLAS STRAUSFELD/UNIVERSITY OF ARIZONA
Fossils of a tiny sea creature that died more than half a billion years ago may compel a science textbook rewrite of how brains evolved.
A study published in Science – led by Nicholas Strausfeld,a Regents Professor in the University of Arizona Department of Neuroscience, and Frank Hirth, a reader of evolutionary neuroscience at King's College London – provides the first detailed description of Cardiodictyon catenulum, a wormlike animal preserved in rocks in China's southern Yunnan province. Measuring barely half an inch (less than 1.5 centimeters) long and initially discovered in 1984, the fossil had hidden a crucial secret until now: a delicately preserved nervous system, including a brain.
"To our knowledge, this is the oldest fossilized brain we know of, so far," Strausfeld said.
Cardiodictyon belonged to an extinct group of animals known as armored lobopodians, which were abundant early during a period known as the Cambrian, when virtually all major animal lineages appeared over an extremely short time between 540 million and 500 million years ago. Lobopodians likely moved about on the sea floor using multiple pairs of soft, stubby legs that lacked the joints of their descendants, the euarthropods – Greek for "real jointed foot." Today's closest living relatives of lobopodians are velvet worms that live mainly in Australia, New Zealand and South America.
A debate going back to the 1800s
Fossils of Cardiodictyon reveal an animal with a segmented trunk in which there are repeating arrangements of neural structures known as ganglia. This contrasts starkly with its head and brain, both of which lack any evidence of segmentation.
"This anatomy was completely unexpected because the heads and brains of modern arthropods, and some of their fossilized ancestors, have for over a hundred years been considered as segmented," Strausfeld said.
According to the authors, the finding resolves a long and heated debate about the origin and composition of the head in arthropods, the world's most species-rich group in the animal kingdom. Arthropods include insects, crustaceans, spiders and other arachnids, plus some other lineages such as millipedes and centipedes.
"From the 1880s, biologists noted the clearly segmented appearance of the trunk typical for arthropods, and basically extrapolated that to the head," Hirth said. "That is how the field arrived at supposing the head is an anterior extension of a segmented trunk."
"But Cardiodictyon shows that the early head wasn't segmented, nor was its brain, which suggests the brain and the trunk nervous system likely evolved separately," Strausfeld said.
The fossilized Cardiodictyon catenulum was discovered in 1984 among a diverse assemblage of extinct creatures known as the Chengjian fauna in Yunnan, China. In this photo, the animal's head is to the right.
CREDIT
Nicholas Strausfeld/University of Arizona
Brains do fossilize
Cardiodictyon was part of the Chengjiang fauna, a famous deposit of fossils in the Yunnan Province discovered by paleontologist Xianguang Hou. The soft, delicate bodies of lobopodians have preserved well in the fossil record, but other than Cardiodictyon none have been scrutinized for their head and brain, possibly because lobopodians are generally small. The most prominent parts of Cardiodictyon were a series of triangular, saddle-shaped structures that defined each segment and served as attachment points for pairs of legs. Those had been found in even older rocks dating back to the advent of the Cambrian.
"That tells us that armored lobopodians might have been the earliest arthropods," Strausfeld said, predating even trilobites, an iconic and diverse group of marine arthropods that went extinct around 250 million years ago.
"Until very recently, the common understanding was 'brains don't fossilize,'" Hirth said. "So you would not expect to find a fossil with a preserved brain in the first place. And, second, this animal is so small you would not even dare to look at it in hopes of finding a brain.”
However, work over the last 10 years, much of it done by Strausfeld, has identified several cases of preserved brains in a variety of fossilized arthropods.
Fossilized head of Cardiodictyon catenulum (anterior is to the right). The magenta-colored deposits mark fossilized brain structures.
CREDIT
Nicholas Strausfeld
A common genetic ground plan for making a brain
In their new study, the authors not only identified the brain of Cardiodictyon but also compared it with those of known fossils and of living arthropods, including spiders and centipedes. Combining detailed anatomical studies of the lobopodian fossils with analyses of gene expression patterns in their living descendants, they conclude that a shared blueprint of brain organization has been maintained from the Cambrian until today.
"By comparing known gene expression patterns in living species," Hirth said, "we identified a common signature of all brains and how they are formed."
In Cardiodictyon, three brain domains are each associated with a characteristic pair of head appendages and with one of the three parts of the anterior digestive system.
"We realized that each brain domain and its corresponding features are specified by the same combination genes, irrespective of the species we looked at," added Hirth. "This suggested a common genetic ground plan for making a brain."
Lessons for vertebrate brain evolution
Hirth and Strausfeld say the principles described in their study probably apply to other creatures outside of arthropods and their immediate relatives. This has important implications when comparing the nervous system of arthropods with those of vertebrates, which show a similar distinct architecture in which the forebrain and midbrain are genetically and developmentally distinct from the spinal cord, they said.
Strausfeld said their findings also offer a message of continuity at a time when the planet is changing dramatically under the influence of climatic shifts.
"At a time when major geological and climatic events were reshaping the planet, simple marine animals such as Cardiodictyon gave rise to the world's most diverse group of organisms – the euarthropods – that eventually spread to every emergent habitat on Earth, but which are now being threatened by our own ephemeral species."
The paper, "The Lower Cambrian Lobopodian Cardiodictyon Resolves the Origin of Euarthropod Brains" was co-authored by Xianguang Hou at the Yunnan Key Laboratory for Paleontology in Yunnan University in Kunming, China, and Marcel Sayre, who has appointments at Lund University in Lund, Sweden, and at the Department of Biological Sciences at Macquarie University in Sydney.
Funding for this work was provided by the National Science Foundation, the University of Arizona Regents Fund, and the UK Biotechnology and Biological Sciences Research Council.
A new study published in Science reports results from the first-ever global field assessment of the ecological impacts of grazing in drylands. The international research team found that grazing can have positive effects on ecosystem services, particularly in species-rich rangelands, but these effects turn to negative under a warmer climate.
Grazing is an essential land use that sustains the livelihood of billions of people and is tightly linked to many UN Sustainable Development Goals. Grazing is particularly important in drylands, which cover about 41% of the Earth's land surface, host one in three humans inhabiting our planet and over 50% of all livestock existing in our planet.
Despite the importance of grazing for humans and ecosystems, to date no previous study had attempted to characterize its impacts on the delivery of ecosystem services at the global scale using field data. For doing so, an international research team of more than 100 specialists, led by Dr. Fernando T. Maestre (University of Alicante, Spain), carried out a unique global survey conducted in 326 drylands located in 25 countries from six continents.
“We used standardized protocols to assess the impacts of increasing grazing pressure on the capacity of drylands to deliver nine essential ecosystem services, including soil fertility and erosion, forage/wood production and climate regulation. Doing so allowed us to characterize how the impacts of grazing depend on local climatic, soil and local biodiversity conditions, and to gain additional insights on the role of biodiversity on the provision of ecosystem services essential to sustain human livelihoods”, says Dr. Maestre, director of the Dryland Ecology and Global Change Laboratory (Alicante, Spain).
Researchers found that the relationships between climate, soil conditions, biodiversity and the ecosystem services measured varied with grazing pressure. "The effects of increasing grazing pressure on ecosystem services were mostly negative in warmer drylands. These results highlight the importance of managing grazing locally, to cope with ongoing climate change in drylands, a particularly important issue in oak woodlands (montados) that we studied in Portugal and were part of this work” points Dr. Alice Nunes from the Centre for Ecology, Evolution and Environmental Changes – cE3c, at the Faculty of Sciences of the University of Lisbon (Ciências ULisboa) and coauthor of the study.
The impacts of increasing grazing pressure shifted from mostly positive in colder drylands with a lower rainfall seasonality and higher plant species richness to negative in hotter drylands with lower plant diversity and higher rainfall seasonality. “There is no one-size-fits-all when it comes to grazing in drylands. Any effects of grazing, particularly overgrazing, will vary across the globe, making it important to consider local condition when managing livestock and wild herbivores” says Dr. David Eldridge from the University of New South Wales (Australia) and coauthor of the study.
The authors also found positive relationships between plant species richness and the delivery of multiple ecosystem services such as soil carbon storage, erosion control, and both forage quality and quantity, regardless of grazing pressure. “Our results highlight the importance of conserving and restoring diverse plant communities to prevent land degradation, ensure the delivery of essential ecosystems services for humans, and mitigate climate change in grazed drylands”, says the PhD student Melanie Köbel from cE3c at Ciências ULisboa and coauthor of the study.
The findings of this study are of great relevance for achieving a more sustainable management of grazing, as well as for establishing effective management and restoration actions aimed at mitigating the effects of ongoing climate change and desertification across global drylands.
This work has been carried out as part of the BIODESERT project, awarded by the Consolidator Grant program of the European Research Council (ERC) to Fernando T. Maestre. “I am very grateful to the ERC for supporting this global survey, as such a high risk-high gain project would have not been possible without the generous funding and freedom that comes with an ERC grant. And of course, it would not have been possible without our network of international collaborators, who provided their expertise, resources, and work to survey sites in their respective study areas. The BIODESERT survey also provides a very nice example of the power of global and collaborative research networks to conduct frontier research”, says Dr. Maestre.
Ranchers driving livestock in Patagonia (Argentina).
CREDIT
Sergio Velasco Ayuso.
Using a standardized survey at 98 sites across six continents, we show that the impacts of increased grazing pressure on the delivery of fundamental ecosystem services depend on climate, soil, and biodiversity across drylands worldwide. Increasing grazing pressure reduced ecosystem service delivery in warmer and species-poor drylands, whereas positive effects of grazing were observed in colder and species-rich areas.
CREDIT
Illustration by Cirenia Arias Baldrich.
Sheep grazing in a semiarid Patagonian rangeland (Argentina).
AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)
Grazing is the most extensive type of land use worldwide, but how does it affect a region’s ecosystem services? Fernando Maestre and colleagues now show in a global survey that grazing’s impact depends on its interaction with other factors such as biodiversity, climate, and soil composition. Learning more about grazing’s effect on ecosystem services is particularly critical for drylands, which make up 78% of global rangelands where grazing provides nutrition and income for one billion people. Maestre et al. studied grazing’s impacts through a survey of plots ranging from low to high grazing pressure by livestock and some natural herbivores, at 98 dryland sites across six continents. They evaluated nine ecosystem services in these plots, including plant, animal, and soil organism diversity, water regulation, carbon storage, erosion, and provisioning of materials such as wood, among other services. The researchers found that, on average, increasing grazing pressure had positive impacts on ecosystem services in cold sites rich in plant species diversity, but negative effects in warmer sites with lower plant species diversity. Efforts to promote diverse grazing systems could limit some of these negative effects and increase soil carbon storage, according to the researchers. In a related Perspective, Amy Ganguli and Megan O’Rourke discuss how this grazing study and others need transdisciplinary context and cooperation so that their findings can be turned into actionable climate change policy.
IMAGE: A REACTION CELL TESTS COPPER-IRON PLASMONIC PHOTOCATALYSTS FOR HYDROGEN PRODUCTION FROM AMMONIA.view more
CREDIT: BRANDON MARTIN/RICE UNIVERSITY
HOUSTON – (Nov. 24, 2022) – Rice University researchers have engineered a key light-activated nanomaterial for the hydrogen economy. Using only inexpensive raw materials, a team from Rice’s Laboratory for Nanophotonics, Syzygy Plasmonics Inc. and Princeton University’s Andlinger Center for Energy and the Environment created a scalable catalyst that needs only the power of light to convert ammonia into clean-burning hydrogen fuel.
The research is published online today in the journal Science.
The research follows government and industry investment to create infrastructure and markets for carbon-free liquid ammonia fuel that will not contribute to greenhouse warming. Liquid ammonia is easy to transport and packs a lot of energy, with one nitrogen and three hydrogen atoms per molecule. The new catalyst breaks those molecules into hydrogen gas, a clean-burning fuel, and nitrogen gas, the largest component of Earth’s atmosphere. And unlike traditional catalysts, it doesn’t require heat. Instead, it harvests energy from light, either sunlight or energy-stingy LEDs.
The pace of chemical reactions typically increases with temperature, and chemical producers have capitalized on this for more than a century by applying heat on an industrial scale. The burning of fossil fuels to raise the temperature of large reaction vessels by hundreds or thousands of degrees results in an enormous carbon footprint. Chemical producers also spend billions of dollars each year on thermocatalysts — materials that don’t react but further speed reactions under intense heating.
“Transition metals like iron are typically poor thermocatalysts,” said study co-author Naomi Halas of Rice. “This work shows they can be efficient plasmonic photocatalysts. It also demonstrates that photocatalysis can be efficiently performed with inexpensive LED photon sources.”
“This discovery paves the way for sustainable, low-cost hydrogen that could be produced locally rather than in massive centralized plants,” said Peter Nordlander, also a Rice co-author.
The best thermocatalysts are made from platinum and related precious metals like palladium, rhodium and ruthenium. Halas and Nordlander spent years developing light-activated, or plasmonic, metal nanoparticles. The best of these are also typically made with precious metals like silver and gold.
Following their 2011 discovery of plasmonic particles that give off short-lived, high-energy electrons called “hot carriers,” they discovered in 2016 that hot-carrier generators could be married with catalytic particles to produce hybrid “antenna-reactors,” where one part harvested energy from light and the other part used the energy to drive chemical reactions with surgical precision.
Halas, Nordlander, their students and collaborators have worked for years to find non-precious metal alternatives for both the energy-harvesting and reaction-speeding halves of antenna reactors. The new study is a culmination of that work. In it, Halas, Nordlander, Rice alumnus Hossein Robatjazi, Princeton engineer and physical chemist Emily Carter, and others show that antenna-reactor particles made of copper and iron are highly efficient at converting ammonia. The copper, energy-harvesting piece of the particles captures energy from visible light.
“In the absence of light, the copper-iron catalyst exhibited about 300 times lower reactivity than copper-ruthenium catalysts, which is not surprising given that ruthenium is a better thermocatalyst for this reaction,” said Robatjazi, a Ph.D. alumnus from Halas’ research group who is now chief scientist at Houston-based Syzygy Plasmonics. “Under illumination, the copper-iron showed efficiencies and reactivities that were similar to and comparable with those of copper-ruthenium.
Syzygy has licensed Rice’s antenna-reactor technology, and the study included scaled-up tests of the catalyst in the company’s commercially available, LED-powered reactors. In laboratory tests at Rice, the copper-iron catalysts had been illuminated with lasers. The Syzygy tests showed the catalysts retained their efficiency under LED illumination and at a scale 500 times larger than lab setup.
“This is the first report in the scientific literature to show that photocatalysis with LEDs can produce gram-scale quantities of hydrogen gas from ammonia,” Halas said. “This opens the door to entirely replace precious metals in plasmonic photocatalysis.”
“Given their potential for significantly reducing chemical sector carbon emissions, plasmonic antenna-reactor photocatalysts are worthy of further study,” Carter added. “These results are a great motivator. They suggest it is likely that other combinations of abundant metals could be used as cost-effective catalysts for a wide range of chemical reactions.”
Halas is Rice’s Stanley C. Moore Professor of Electrical and Computer Engineering and a professor of chemistry, bioengineering, physics and astronomy, and materials science and nanoengineering. Nordlander is Rice’s Wiess Chair and Professor of Physics and Astronomy, and professor of electrical and computer engineering, and materials science and nanoengineering. Carter is Princeton's Gerhard R. Andlinger Professor in Energy and Environment at the Andlinger Center for Energy and the Environment, senior strategic adviser for sustainability science at the Princeton Plasma Physics Laboratory, and professor of mechanical and aerospace engineering and of applied and computational mathematics. Robatjazi is also an adjunct professor of chemistry at Rice.
Halas and Nordlander are Syzygy co-founders and hold an equity stake in the company.
The research was supported by the Welch Foundation (C-1220, C-1222), the Air Force Office of Scientific Research (FA9550-15-1-0022), Syzygy Plasmonics, the Department of Defense and Princeton University.
Additional co-authors include Yigao Yuan, Jingyi Zhou, Aaron Bales, Lin Yuan, Minghe Lou and Minhan Lou of Rice, Linan Zhou of both Rice and South China University of Technology, Suman Khatiwada of Syzygy Plasmonics, and Junwei Lucas Bao of both Princeton and Boston College.
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A reaction cell (left) and the photocatalytic platform (right) used on tests of copper-iron plasmonic photocatalysts for hydrogen production from ammonia at Syzygy Plasmonics in Houston. All reaction energy for the catalysis came from LEDs that produced light with a wavelength of 470 nanometers.
CREDIT
Syzygy Plasmonics, Inc.
The photocatalytic platform used on tests of copper-iron plasmonic photocatalysts for hydrogen production from ammonia.
CREDIT
Photo by Brandon Martin/Rice University
Peer-reviewed paper:
"Earth-abundant photocatalyst for H2 generation from NH3 with light-emitting diode illumination" | Science | DOI: 10.1126/science.abn5636
Yigao Yuan, Linan Zhou, Hossein Robatjazi, Junwei Lucas Bao, Jingyi Zhou, Aaron Bayles, Lin Yuan, Minghe Lou, Minhan Lou, Suman Khatiwada, Emily A. Carter, Peter Nordlander, Naomi J. Halas
The photocatalytic platform used on tests of copper-iron plasmonic photocatalysts for hydrogen production from ammonia. (Credit: Photo by Brandon Martin/Rice University)
A reaction cell (left) and the photocatalytic platform (right) used on tests of copper-iron plasmonic photocatalysts for hydrogen production from ammonia at Syzygy Plasmonics in Houston. All reaction energy for the catalysis came from LEDs that produced light with a wavelength of 470 nanometers. (Credit: Syzygy Plasmonics, Inc.)
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Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 4,240 undergraduates and 3,972 graduate students, Rice’s undergraduate student-to-faculty ratio is just under 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for lots of race/class interaction and No. 1 for quality of life by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger’s Personal Finance.
IMAGE: COMPUTATIONS FOR THE PROJECT WAS PERFORMED AT PRINCETON'S HIGH PERFORMANCE COMPUTING RESEARCH CENTER.view more
CREDIT: PHOTO BY DENISE APPLEWHITE, PRINCETON UNIVERSITY OFFICE OF COMMUNICATIONS
Researchers at Princeton and Rice universities have combined iron, copper, and a simple LED light to demonstrate a low-cost technique that could be key to distributing hydrogen, a fuel that packs high amounts of energy with no carbon pollution.
The researchers used experiments and advanced computation to develop a technique using nanotechnology to split hydrogen from liquid ammonia, a process that until now has been expensive and energy intensive.
In an article published online Nov. 24 in the journal Science, the researchers describe how they used light from a standard LED to crack the ammonia without the need for high temperatures or expensive elements typically demanded by such chemistry. The technique overcomes a critical hurdle toward realizing hydrogen’s potential as a clean, low-emission fuel that could help meet energy demands without worsening climate change.
“We hear a lot about hydrogen being the ultimate clean fuel, if only it was less expensive and easy to store and retrieve for use,” said Naomi Halas, a professor at Rice University and one of the study’s principal authors. “This result demonstrates that we are moving rapidly towards that goal, with a new, streamlined way to release hydrogen on-demand from a practical hydrogen storage medium using earth-abundant materials and the technological breakthrough of solid-state lighting.”
Hydrogen offers many advantages as a green fuel including high energy density and zero carbon pollution. It is also used ubiquitously in industry, for example to make fertilizer, food, and metals. But pure hydrogen is expensive to compress for transport and is difficult to store for long periods. In recent years, scientists have sought to use intermediate chemicals to transport and store hydrogen. One of the most promising hydrogen carriers is ammonia (NH3), comprised of three hydrogen atoms and one nitrogen atom. Unlike pure hydrogen gas (H2), liquid ammonia, although hazardous, has existing systems for safe transportation and storage.
“This discovery paves the way for sustainable, low-cost hydrogen that could be produced locally rather than in massive centralized plants,” said Peter Nordlander, a professor at Rice and another principal author.
One persistent problem for advocates has been that cracking ammonia into hydrogen and nitrogen often requires high temperatures to drive the reaction. Conversion systems can require temperatures above 400 degrees Celsius (732 degrees Fahrenheit). That demands a lot of energy to convert the ammonia, as well as special equipment to handle the operation.
Researchers led by Halas and Nordlander at Rice University, and Emily Carter, the Gerhard R. Andlinger Professor in Energy and the Environment and Professor of Mechanical and Aerospace Engineering and Applied and Computational Mathematics at Princeton, wanted to transform the splitting process to make ammonia a more sustainable and economically viable carrier for hydrogen fuels. Using ammonia as a hydrogen carrier has drawn considerable research interest because of its potential to drive a hydrogen economy, as a recent review by the American Chemical Society shows.
Industrial operations often crack ammonia at high temperatures using a wide variety of materials as catalysts, which are materials that accelerate a chemical reaction without being changed by the reaction. Previous research has demonstrated that it is possible to lower the reaction temperature by using a ruthenium catalyst. But ruthenium, a metal in the platinum group, is expensive. The researchers believed they could use nanotechnology to allow cheaper elements like copper and iron to be used as a catalyst instead.
The researchers also wanted to tackle the energy cost of cracking ammonia. Current methods use a lot of heat to break the chemical bonds that hold ammonia molecules together. The researchers believed they could harness light to sever the chemical bonds like a scalpel rather than using heat to shatter them like a hammer. To do so, they turned to nanotechnology, along with a much cheaper catalyst containing iron and copper.
The combination of nanotechnology’s tiny metal structures and light is a relatively new field called plasmonics. By shining light into structures smaller than a single wavelength of light, engineers can manipulate the light waves in unusual and specific ways. In this case, the Rice team wanted to use this engineered light to excite electrons in the metal nanoparticles as a way to split the ammonia into its hydrogen and nitrogen components without the need for intense heat. Because plasmonics requires certain types of metals, such as copper, silver, or gold, the researchers added the iron to copper before creating the tiny structures. When finished, the copper structures behave as antennas to manipulate the light from the LED to excite the electrons to higher energies, while the iron atoms embedded in the copper act as catalysts to accelerate the reaction carried out by excited electrons.
The researchers created the structures and conducted the experiments in laboratories at Rice. They were able to adjust many variables around the reaction such as the pressure, the intensity of the light and the light’s wavelength. But calibrating the exact parameters was daunting. To investigate how these variables affected the reaction, the researchers worked with principal author Carter, who specializes in detailed investigations of reactions at the molecular level. Using Princeton’s high-performance computing system, the Terascale Infrastructure for Groundbreaking Research in Engineering and Science (TIGRESS), Carter and her postdoctoral fellow, Junwei Lucas Bao, ran the reactions through her specialized quantum mechanics simulator uniquely able to study excited electron catalysis. Molecular interactions of such reactions are incredibly complex, but Carter and her fellow researchers are able to use the simulator to understand which variables should be adjusted to further the reaction.
“With the quantum mechanics simulations, we can determine the rate-limiting reaction steps,” said Carter, who also holds appointments at Princeton’s Andlinger Center for Energy and the Environment, in applied and computational mathematics, and at the Princeton Plasma Physics Laboratory. “These are the bottlenecks.”
By fine-turning the process, while utilizing the atomic-scale understanding Carter and her team provided, the Rice team was able to consistently extract hydrogen from ammonia using only light from energy-efficient LEDs at room temperature with no additional heating. The researchers say the process is scalable. In further research, they plan to investigate other possible catalysts with an eye to increasing the process efficiency and decreasing the cost.
Carter, who also currently chairs the National Academies’ committee on carbon utilization, said a critical next step will be to decrease the costs and carbon pollution involved with creating the ammonia that begins the transportation cycle. Currently, most ammonia is created at high temperatures and pressures using fossil fuels. The process is both energy intensive and polluting. Carter said many researchers are working to develop green techniques for the production of ammonia as well.
“Hydrogen is used ubiquitously in industry and will be used increasingly as fuel as the world seeks to decarbonize its energy sources,” she said. “However, today it is mostly made unsustainably from natural gas – creating carbon dioxide emissions – and is difficult to transport and store. Hydrogen needs to be made and transported sustainably where it is needed. If carbon-emission-free ammonia could be produced, for example by electrolytic reduction of nitrogen using decarbonized electricity, it could be transported, stored, and possibly serve as an on-demand source of green hydrogen using the LED-illuminated iron-copper photocatalysts reported here.”
The article, Earth-abundant photocatalyst for H2 generation from NH3 with light-emitting diode illumination, was published in the Nov. 25 issue of Science. Besides Carter, Halas and Nordlander, co-authors include Hossein Robatjazi, who received his doctorate at Rice and is now chief scientist of Syzygy Plasmonics; Junwei Lucas Bao, who is now a professor at Boston College; Yigao Yuan, Jingyi Zhou, Aaron Bales, Lin Yuan, Minghe Lou and Minhan Lou of Rice University; Linan Zhou of both Rice and South China University of Technology, and Suman Khatiwada of Syzygy Plasmonics. Halas and Nordlander are co-founders of Syzygy and hold equity in the company.
Support for the research was provided in part by the Welch Foundation, the Air Force Office of Scientific Research, Syzygy Plasmonics, and the Department of Defense.
- Rice University’s Office of Public Affairs contributed to this article.
