Rice lab’s catalyst could be key for hydrogen economy
Inexpensive catalyst uses energy from light to turn ammonia into hydrogen fuel
Peer-Reviewed PublicationIMAGE: 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.
-30-
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
https://doi.org/10.1126/science.abn5636
VIDEO is available at:
Video produced by Brandon Martin/Rice University
High-resolution IMAGES are available for download at:
https://news-network.rice.edu/news/files/2022/11/1205_PHOTOCAT-1-WEB.jpg
A reaction cell tests copper-iron plasmonic photocatalysts for hydrogen production from ammonia. (Credit: Photo by Brandon Martin/Rice University)
https://news-network.rice.edu/news/files/2022/11/1205_PHOTOCAT-2-WEB.jpg
The photocatalytic platform used on tests of copper-iron plasmonic photocatalysts for hydrogen production from ammonia. (Credit: Photo by Brandon Martin/Rice University)
https://news-network.rice.edu/news/files/2022/11/1205_PHOTOCAT-3-WEB.jpg
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.)
https://news-network.rice.edu/news/files/2022/11/1205_PHOTOCAT-4-WEB-Halas.jpg
CAPTION: Naomi Halas. (Credit: Photo by Jeff Fitlow/Rice University)
https://news-network.rice.edu/news/files/2022/11/1205_PHOTOCAT-5-WEB-Nordlander.jpg
CAPTION: Peter Nordlander. (Credit: Photo by Jeff Fitlow/Rice University)
https://news-network.rice.edu/news/files/2022/11/1205_PHOTOCAT-6-WEB-Robatjazi.jpg
CAPTION: Hossein Robatjazi. (Credit: Photo by Jeff Fitlow/Rice University)
Related stories:
Measurement of ‘hot’ electrons could have solar energy payoff: https://news2.rice.edu/2011/05/05/measurement-of-hot-electrons-could-have-solar-energy-payoff/
Rice’s ‘antenna-reactor’ catalysts offer best of both worlds: https://news2.rice.edu/2016/07/18/rices-antenna-reactor-catalysts-offer-best-of-both-worlds/
Wasted Energy: What if we could make chemical reactions on an industrial scale much more energy efficient?: https://magazine.rice.edu/winter-2018/we-dont-know#wasted-energy
Links:
Laboratory for Nanophotonics: http://lanp.blogs.rice.edu
Halas Research Group: https://halas.rice.edu
Nordlander Nanophotonics Group: https://nordlander.rice.edu
Wiess School of Natural Sciences: https://naturalsciences.rice.edu
This release can be found online at https://news.rice.edu/news/2022/rice-labs-catalyst-could-be-key-hydrogen-economy.
Follow Rice News and Media Relations via Twitter @RiceUNews.
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.
JOURNAL
Science
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Earth-abundant photocatalyst for H2 generation from NH3 with light-emitting diode illumination
ARTICLE PUBLICATION DATE
24-Nov-2022
COI STATEMENT
Halas and Nordlander are Syzygy co-founders and hold an equity stake in the company.
Researchers create green fuel with the
flip of a light switch
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.
JOURNAL
Science
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Earth-abundant photocatalyst for H2 generation from NH3 with light-emitting diode illumination
ARTICLE PUBLICATION DATE
25-Nov-2022
COI STATEMENT
Halas and Nordlander are Syzygy co-founders and hold an equity stake in the company.
No comments:
Post a Comment