Researchers from Princeton and Rice universities found that iron, By combining copper and simple LEDs, they demonstrated that hydrogen, a high-energy fuel, is key to distribution.
Researchers have used experiments and advanced calculations to develop a technology that uses nanotechnology to separate hydrogen from liquid hydrogen, which until now has been expensive and energy-intensive.
In an article published in an online journal. ScienceThe researchers describe how they used light from a standard LED to crack ammonia without the need for high temperatures or the expensive chemicals often demanded by chemistry. The technology overcomes a critical hurdle to realizing hydrogen’s potential as a clean, low-emissions fuel that can meet energy needs without exacerbating climate change.
“We hear a lot about hydrogen being the ultimate clean fuel if it’s cheap and easy to store and use,” said Naomi Halas, a professor at Rice University and one of the study’s lead authors. “This result demonstrates that we are moving rapidly toward this goal with a new, easy way to release hydrogen on demand, using earth-abundant materials, and the technological breakthroughs of solid-state lighting.”
Hydrogen offers many advantages as a green fuel, including energy density and zero carbon pollution. Fertilizer to make food and metals; Widely used in industry. But pure hydrogen is expensive to compress for transport and difficult to store for long periods of time. In recent years, scientists have attempted to use chemical intermediates to transport and store hydrogen. The most promising hydrogen carrier is ammonia (NH).3) consists of three hydrogen atoms and one nitrogen atom. Pure hydrogen gas (H2Although liquid ammonia is hazardous, there are systems in place for safe transportation and storage.
“This discovery paves the way for sustainable and cost-effective hydrogen that can be produced locally rather than in large, centralized plants,” said Rice professor Peter Nordlander and another lead author.
A persistent problem with catalysts is that high temperatures are often required to drive the reaction to crack ammonia into hydrogen and nitrogen. Conversion systems may require temperatures above 400 degrees Celsius (732 degrees Fahrenheit). It requires a lot of energy to convert to ammonia, as well as special equipment to handle the operation.
Researchers led by Halas and Nordlander of Rice University and Emily Carter; Emily Carter, the Gerhard R. Andlinger Professor of Energy and the Environment and a professor of mechanical and aeronautical engineering and applied and computational mathematics at Princeton, wanted to change the process of breaking down ammonia into ammonia. A more sustainable and economically viable carrier for hydrogen fuels. The use of ammonia as a hydrogen carrier has attracted much research interest because of its potential to drive the hydrogen economy, according to a recent review by the American Chemical Society.
Industries use many catalysts, which often crack ammonia at high temperatures and speed up chemical reactions. Previous research has demonstrated that the reaction temperature can be reduced by using a ruthenium catalyst. But ruthenium, a platinum group metal, is expensive. The researchers believed that nanotechnology could be used to replace cheaper elements such as copper and iron as catalysts.
The researchers also want to address the energy cost of ammonia cracking. Current methods use a lot of heat to break the chemical bonds that hold the ammonia molecules together. The researchers believe they can harness light to split chemical bonds like a scalpel, rather than using heat to crack them like a hammer. To do so, they turned to nanotechnology, along with inexpensive catalysts containing iron and copper.
The combination of light with the tiny metallic structures of nanotechnology is a new field called plasmonics. By shining light into structures smaller than a single wavelength of light, engineers can manipulate light waves in unique and precise ways. In this case, Rice’s team wanted to use this engineered light to excite electrons in metal nanoparticles as a way to split ammonia into its hydrogen and nitrogen components without the need for intense heat. Plasmonics are copper, Because some type of metal, such as silver or gold, is required, the researchers added iron to the copper before creating the microstructures. When it was finished, The copper structures act as antennas for the light from the LED to excite electrons to higher energies. Iron atoms embedded in copper act as catalysts to accelerate the reaction of excited electrons.
The researchers created the structures and conducted experiments in a laboratory at Rice. They are pressure, Several variables surrounding the response, such as the intensity of the light and the wavelength of the light, were adjusted. But it’s a lot to adjust the exact parameters. To investigate how these variables affect the response; The researchers worked with lead author Carter, who specializes in detailed investigations of reactions at the molecular level. Princeton’s high-performance computing system; Terascale Infrastructure for Engineering and Scientific Ground Research (TIGRESS); Carter and her postdoctoral fellow, Junwei Lucas Bao, were able to uniquely study excited-electron catalysis through her specialized quantum mechanics simulator. The molecular interplay of such reactions is incredibly complex, but Carter and her researchers can use the simulator to understand what changes they should be prepared to respond to again.
“With quantum mechanical simulations, we can determine the rate-limiting steps of a reaction,” said Carter, who holds an appointment in Applied and Computational Mathematics and the Princeton Plasma Physics Laboratory at Princeton’s Andlinger Center for Energy and the Environment. “These are blockages.”
Leveraging the atomic-scale understanding provided by Carter and her team by fine-tuning the process, Rice’s team was able to continuously extract hydrogen from ammonia using only light from energy-efficient LEDs at room temperature without the need for additional heating. Researchers say the process is massive. In further research, They plan to investigate other potential catalysts with an eye toward reducing process efficiency and cost.
Carter, who is also the current chair of the National Academy’s Committee on Carbon Utilization, said creating the ammonia that starts the transportation cycle will take an important next step in reducing costs and carbon pollution. Currently, most ammonia is created using fossil fuels at high temperatures and pressures. The process is both energy intensive and polluting. Many researchers are working to develop green technologies for ammonia production, Carter said.
“Hydrogen is used everywhere in industry and will increasingly become a fuel as the world tries to decarbonize its energy sources,” she said. “However, most of the carbon dioxide emissions created today come from natural gas, which is unsustainably produced and difficult to transport and store. Hydrogen needs to be created where it is needed and delivered sustainably. For example, if ammonia can be produced without carbon emissions, For example, by electrolytically reducing nitrogen using carbon-discharged electricity. It can be used as an on-demand source of green hydrogen using LED-illuminated iron-copper photocatalysts. Reported here.”