ŷ���ڱ���Ƶ Boulder chemist Niels Damrauer and his research colleagues use visible light to break environmentally persistent carbon-fluorine bonds in PFAS

The strength of the bond between carbon and fluorine can be both a positive and a negative. Because of its seeming unbreakablility, food doesn’t stick to Teflon-coated frying pans and water rolls off rain jackets rather than soaking in.

However, these bonds are also what put the “forever” in “forever chemicals,” the common name for the thousands of compounds that are perfluoroalkyl and polyfluoroalkyl substances (PFAS). PFAS are so commercially abundant that they can be found in everything from candy wrappers to home electronics and guitar strings—to say nothing of their presence in industrial products.

The C-F bond is so difficult to break that the products containing it could linger in the environment for thousands of years. And when these molecules linger in a human body, they are associated with increased risk for cancer, thyroid disease, asthma and a host of other adverse health outcomes.

“There are a lot of interesting things about those bonds,” says Niels Damrauer, a University of ŷ���ڱ���Ƶ Boulder professor of chemistry and fellow in the Renewable and Sustainable Energy Institute. “(The C-F bond) is very unnatural. There are a lot of chemical bonds in the world that natural systems have evolved to be able to destroy, but C-F bonds are uncommon in nature, so there aren’t bacteria that have evolved to break those down.”

Instead of long-used methods of breaking or activating chemical bonds, Damrauer and his research colleagues have looked to light. , the scientists detail an important finding in their ongoing research, showing how a light-driven catalyst can efficiently reduce C-F bonds.

“What we’re really trying to do is figure out sustainable ways of making transformations,” Damrauer explains. “We’re asking, ‘Can we change chemical reactivity through light absorption that we wouldn’t necessarily be able to achieve without it?’ For example, you can break down PFAS at thousands of degrees, but that’s not sustainable. We’re using light to do this, a reagent that’s very abundant and that’s sustainable.”

A foundation of spectroscopy

An important foundation for this research is spectroscopy, which can use light to study chemical reactions that are initiated with light, as well as the properties of molecules that have absorbed light. As a spectroscopist, Damrauer does this in a number of ways on a variety of time scales: “We can put light into molecules and study what they do in trillionths of a second, or we can follow the paths of molecules once they have absorbed light and what they do with the excess energy.”

Damrauer and his colleagues, including those in his research group, frequently work in photoredox catalysis, a branch of photochemistry that studies the giving and taking of electrons as a way to initiate chemical reactions.

“The idea is that in some molecules, absorption of light changes their properties in terms of how they give up electrons or take in electrons from the environment,” Damrauer explains. “That giving and taking—giving an electron is called reduction and taking is called oxidation—so that if you can put light in and cause molecules to be good reducers or good oxidizers, it changes some things you can do. We create situations where we catalyze transformations and cause a chemical reaction to occur.”

Damrauer and his research colleague Garret Miyake, formerly of the ŷ���ڱ���Ƶ Boulder Department of Chemistry and now at ŷ���ڱ���Ƶ State University, have collaborated for many years to understand molecules that give up electrons—the process of reduction—after absorbing light.

Several years ago, Miyake and his research group discovered a catalyst to reduce benzene, a molecule that’s notoriously difficult to reduce, once it had absorbed light. Damrauer and his graduate students Arindam Sau and Nick Pompetti worked with Miyake and his postdoc and students to understand why and how this catalyst worked, and they began looking at whether this and similar catalysts could activate the C-F bond—either breaking it or remaking it in useful products. This team also worked with Rob Paton, a computational chemist at CSU, and his group.

They found that within the scope of their study, the C-F bond in molecules irradiated with visible light—which could, in principle, be derived from the sun—and catalyzed in a system they developed could be activated. They found that several PFAS compounds could then be converted into defluorinated products, essentially breaking the C-F bond and “representing a mild reaction methodology for breaking down these persistent chemicals,” they note in the study.

Making better catalysts

A key element of the study is that the C-F bond is “activated,” meaning it could be broken—in the case of PFAS—or remade. “C-F bonds are precursors to molecules you might want to make in chemistry, like pharmaceuticals or other materials,” Damrauer says. “They’re a building block people don’t use very much because that bond is so strong. But if we can activate that bond and can use it to make molecules, then from a pharmaceutical perspective this system might already be practical.”

While the environmental persistence of PFAS is a serious public health and policy concern, “organofluorines [containing C-F bonds] have a tremendous impact in medicinal, agrochemical and materials sciences as fluorine incorporation results in structures imparting specific beneficial attributes,” Damrauer and his colleagues write.

By pursuing systems that mitigate the negative aspects of C-F bonds and harness the positive, and using the abundant resources of visible light and organic molecules, Damrauer says he hopes this research is a significant step toward sustainably producing products that use light as a reagent rather than heat or precious metal-based catalysts.

While the catalytic process the researchers developed is not yet at a level that it could be used on PFAS in the environment at a large scale, “this fundamental understanding is really important,” Damrauer says. “It allows us to evolve what we do next. While the current iteration isn’t good enough for practical application, we’re working to make better and better catalysts.”

Xin Liu, Arindam Sau, Alexander R. Green, Mihai V. Popescu, Nicholas F. Pompetti, Yingzi Li, Yucheng Zhao, Robert S. Paton and Garret M. Miyake also contributed to this research.

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We developed a way to use light to dismantle PFAS ‘forever chemicals’–long-lasting environmental pollutants

, have earned the nickname of from their extraordinary ability to stick around in the environment long after they’ve been used.

These synthetic compounds, commonly used in consumer products and industrial applications for their water- and grease-resistant properties, are now found practically everywhere .

While many chemicals will degrade after they’re disposed of, PFAS for up to 1,000 years. This durability is great for their use in firefighting foams, nonstick cookware, waterproof clothing and even food packaging.

However, their resilience means that they persist in soil, water and even living organisms. They can accumulate over time and of both ecosystems and humans.

Some initial research has shown potential links between PFAS exposure and various — including cancers, immune system suppression and hormone disruption. These concerns have led scientists to search for these stubborn chemicals.

We’re a team of researchers who developed a chemical system that uses light to break down bonds between carbon and fluorine atoms. These strong chemical bonds help PFAS resist degradation. We in November 2024, and we hope this technique could help address the widespread contamination these substances cause.

Why PFAS compounds are so hard to break down

PFAS compounds have carbon-fluorine bonds, one of the strongest in chemistry. These bonds make PFAS incredibly stable. They resist the degradation processes that usually break down industrial chemicals – , and microbial breakdown.

Conventional water treatment methods , but these processes merely concentrate the contaminants instead of destroying them. The resulting PFAS-laden materials are typically sent to landfills. Once disposed of, they can still leach back into the environment.

for breaking carbon-fluorine bonds depend on use of metals and very . For example, can be used for this purpose. This dependence makes these methods expensive, energy-intensive and challenging to use on a large scale.

How our new photocatalytic system works

The new method our team has developed uses a . A photocatalyst is a substance that speeds up a chemical reaction using light, without being consumed in the process. Our system harnesses energy from cheap blue LEDs to drive a set of chemical reactions.

After absorbing light, the photocatalyst to the molecules containing fluorine, which breaks down the sturdy carbon-fluorine bonds.

By directly targeting and dismantling the molecular structure of PFAS, photocatalytic systems like ours hold the potential for complete mineralization. Complete mineralization is a process that transforms these harmful chemicals into harmless end products, like hydrocarbons and fluoride ions, which degrade easily in the environment. The degraded products can then be safely reabsorbed by plants.

Potential applications and benefits

One of the most promising aspects of this new photocatalytic system is its simplicity. The setup is essentially a small vial illuminated by two LEDs, with two small fans added to keep it cool during the process. It operates under mild conditions and does not use any metals, which are to handle and can sometimes be explosive.

The system’s reliance on light – a readily available and renewable energy source – could make it economically viable and sustainable. As we refine it, we hope that it could one day operate with minimal energy input, outside of the energy powering the light.

This platform can also transform other organic molecules that contain carbon-fluorine bonds into valuable chemicals. For instance, thousands of are commonly available as industrial chemicals and laboratory reagents. These can be transformed into building blocks for making a variety of other materials, including medicines and everyday products.

Challenges and future directions

While this new system shows potential, challenges remain. Currently, we can degrade PFAS only on a small scale. While our experimental setup is effective, it will require substantial scaling up to tackle the PFAS problem on a larger level. Additionally, large molecules with hundreds of carbon-fluorine bonds, like Teflon, do not dissolve into the solvent we use for these reactions, even at high temperatures.

As a result, the system currently can’t break down these materials, and we need to conduct more research.

We also want to improve the long-term stability of these catalysts. Right now, these organic photocatalysts degrade over time, especially when they’re under constant LED illumination. So, designing catalysts that retain their efficiency over the long term will be essential for practical, large-scale use. Developing methods to regenerate or recycle these catalysts without losing performance will also be key for scaling up this technology.

With our colleagues at the , we plan to keep working on light-driven catalysis, aiming to discover more light-driven reactions that . SuPRCat is a -funded nonprofit Center for Chemical Innovation. The teams there are working to develop reactions for more sustainable chemical manufacturing.

The end goal is to create a system that can remove PFAS contaminants from drinking water at purification plants, but that’s still a long way off. We’d also like to one day use this technology to clean up PFAS-contaminated soils, making them safe for farming and restoring their role in the environment.

Arindam Sau is a Ph.D. candidate in the  Department of Chemistry; is a postdoctoral associate in chemistry at ŷ���ڱ���Ƶ State University; is a postdoctoral scholar in chemistry at ŷ���ڱ���Ƶ State University.

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ŷ���ڱ���Ƶ Boulder chemist will use the five-year support to study tailoring cycles affecting energy flow in solar energy conversion

���Ի��é��&�Բ�����;�ѴDzԳٴDzⲹ-�䲹���پ�������, an assistant professor in the University of ŷ���ڱ���Ƶ Boulder Department of Chemistry, has been awarded a .

The fellowships, given by the , are awarded to innovative early-career scientists and engineers, who receive $875,000 over five years to pursue their research.

“These scientists and engineers are the architects of tomorrow, leading innovation with bold ideas and unyielding determination,” said Nancy Lindborg, president and chief executive officer of the Packard Foundation, in announcing the 2024 awards. “Their work today will be the foundation for the breakthroughs of the future, inspiring the next wave of discovery and invention.” 

Montoya-Castillo is a theoretical chemist who that encompasses multidisciplinary skills spanning physical chemistry, condensed matter physics and quantum information science.

Explaining his research that the fellowship will support, Montoya-Castillo notes, “The world’s growing population faces looming food shortages and the pressing need for cheap and sustainable energy sources. Reliable conversion of sunlight–our most abundant energy source–into fuel can address these threats. However, reliable energy conversion requires knowing how to tailor, at an atomic level, photoprotection cycles limiting food production and energy flow in solar cells that convert sunlight into fuel.”

He adds that he “will harness the power of generalized master equations to develop efficient, atomically resolved theories and analysis tools that cut the cost of experiments needed to reveal how to employ chemical modifications to manipulate photoprotection cycles in plants and the photocatalytic activity of metal oxides. Our developments will offer transformative insights into fundamental excitation dynamics in complex materials, enabling the boosting of photosynthetic crop production and optimization of environmentally friendly semiconductors that split water into clean fuels.”

Last year, Montoya-Castillo was named a U.S. Department of Energy Early Career Research Program scientist and earlier this year received the ŷ���ڱ���Ƶ Boulder Marinus Smith Award, which recognizes faculty and staff members who have had a particularly positive impact on students. He received his BA in chemistry and literature from Macaulay Honors College, ŷ���ڱ���ƵNY, and his PhD in chemical physics from Columbia University.

“I’m honored and thrilled to be part of the Packard Fellows class of 2024!” Montoya-Castillo says. “With the help of the Packard Foundation's funding, I look forward to finding new ways to measure and control nonequilibrium energy flow for human use.”

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In newly published study, ŷ���ڱ���Ƶ Boulder chemist Wei Zhang details a new porous material that is less expensive and more sustainable

For a broad range of industries, separating gases is an important part of both process and product—from separating nitrogen and oxygen from air for medical purposes to separating carbon dioxide from other gases in the process of carbon capture or removing impurities from natural gas.

Separating gases, however, can be both energy-intensive and expensive. “For example, when separating oxygen and nitrogen, you need to cool the air to very low temperatures until they liquefy. Then, by slowly increasing the temperature, the gases will evaporate at different points, allowing one to become a gas again and separate out,” explains Wei Zhang, a University of ŷ���ڱ���Ƶ Boulder professor of chemistry and chair of the Department of Chemistry.

“It’s very energy intensive and costly.”

Wei Zhang, a ŷ���ڱ���Ƶ Boulder professor of chemistry, developed a porous material that can accommodate and separate many different gases and is made from common, readily available materials.

Much gas separation relies on porous materials through which gases pass and are separated. This, too, has long presented a problem, because these porous materials generally are specific to the types of gases being separated. Try sending any other types of gas through them, and they don’t work.

However, in , Zhang and his co-researchers detail a new type of porous material that can accommodate and separate many different gases and is made from common, readily available materials. Further, it combines rigidity and flexibility in a way that allows size-based gas separation to happen at a greatly decreased energy cost.

“We are trying to make technology better,” Zhang says, “and improve it in a way that’s scalable and sustainable.”

Adding flexibility

For a long time, the porous materials used in gas separation have been rigid and affinity-based—specific to the types of gases being separated. The rigidity allows the pores to be well-defined and helps direct the gases in separating, but also limits the number of gases that can pass through because of varying molecule sizes.

For several years, Zhang and his research group worked to develop a porous material that introduces an element of flexibility to a linking node in otherwise rigid porous material. That flexibility allows the molecular linkers to oscillate, or move back and forth at a regular speed, changing the accessible pore size in the material and allowing it to be adapted to multiple gases.

“We found that at room temperature, the pore is relatively the largest and the flexible linker barely moves, so most gases can get in,” Zhang says. “When we increase the temperature from room temperature to about 50 degrees (Celsius), oscillation of the linker becomes larger, causing effective pore size to shrink, so larger gases can’t get in. If we keep increasing the temperature, more gases are turned away due to increased oscillation and further reduced pore size. Finally, at 100 degrees, only the smallest gas, hydrogen, can pass through.”

The material that Zhang and his colleagues developed is made of small organic molecules and is most analogous to zeolite, a family of porous, crystalline materials mostly composed of silicon, aluminum and oxygen. “It’s a porous material that has a lot of highly ordered pores,” he says. “You can picture it like a honeycomb. The bulk of it is solid organic material with these regular-sized pores that line up and form channels.”

The researchers used a fairly new type of dynamic covalent chemistry that focuses on the boron-oxygen bond. Using a boron atom with four oxygen atoms around it, they took advantage of the reversibility of the bond between the boron and oxygen, which can break and reform again and again, thus enabling self-correcting, error-proof behavior and leading to the formation of structurally ordered frameworks.

“We wanted to build something with tunability, with responsiveness, with adaptability, and we thought the boron-oxygen bond could be a good component to integrate into the framework we were developing, because of its reversibility and flexibility,” Zhang says.

Graphs charting pore size, gas molecule size and gas uptake.

Sustainable solutions

Developing this new porous material did take time, Zhang says: “Making the material is easy and simple. The difficulty was at the very beginning, when we first obtained the material and needed to understand or elucidate its structure—how the bonds form, how angles form within this material, is it two-dimensional or three-dimensional. We had some challenges because the data looked promising; we just didn’t know how to explain it. It showed certain peaks (x-ray diffraction), but we could not immediately figure out what kind of structure those peaks corresponded to."

So, he and his research colleagues took a step back, which can be an important but little-discussed part of the scientific process. They focused on the small-molecule model system containing the same reactive sites as those in their material to understand how molecular building blocks packed in a solid state, and that helped explain the data.

Zhang adds that he and his co-researchers considered scalability in developing this material, since its potential industrial uses would require large amounts, “and we believe this method is highly scalable. The building blocks are commercially available and not expensive, so it could be adopted by industry when the time is right.”

They have applied for a patent on the material and are continuing the research with other building-block materials to learn the substrate scope of this approach. Zhang also says he sees potential to partner with engineering researchers to integrate the material into membrane-based applications.

“Membrane separations generally require much less energy, so in the long term they could be more sustainable solutions,” Zhang says. “Our goal is to improve technology to meet industry needs in sustainable ways.”

Researchers Yiming Hu, Bratin Sengupta, Hai Long, Lacey J. Wayment, Richard Ciora, Yinghua Jin, Jingyi Wu, Zepeng Lei, Kaleb Friedman, Hongxuan Chen and Miao Yu also contributed to this study.

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Chemistry Professor Gordana Dukovic will pursue research to develop new insights into solar chemistry

University of ŷ���ڱ���Ƶ Boulder scientist Gordana Dukovic has been named a winner, a recognition that will support her research to develop new insights into solar chemistry.

Dukovic, a professor of chemistry and fellow in the Renewable and Sustainable Energy Institute, is one of eight award recipients from universities across the United States who conduct basic research in chemistry or physics. Each winner will receive up to $2 million distributed over five years.

The Brown Investigator Award is given by the , which was founded "to support bold investigations with the potential for transformational discoveries that will ultimately benefit humanity,” according to founder Ross M. Brown. It supports mid-career physics and chemistry researchers in the United States who are pursuing new directions of inquiry.

Gordana Dukovic, a ŷ���ڱ���Ƶ Boulder professor of chemistry, was named one of eight 2024 Brown Investigator Award winners Wednesday.

For Dukovic, that will mean broadening the work that she and the members of her interdisciplinary research group pursue in the field of nanoscience for solar energy harvesting.

“In this work, we often couple nanomaterials with biological catalysts, which are called enzymes,” Dukovic explains. “Nanomaterials can absorb sunlight and then give electrons generated by sunlight to the enzymes, which then do enzyme-catalyzed transformations that make new molecules.

“What we’re finding in our work is that the outcomes of these solar processes are very sensitive to the details of how the nanomaterials interact with enzymes, which are difficult to determine. We know that there are elements of chemical structure that are going to be extremely important for the function of these materials we’re making, but they’re very difficult to see. This award will allow us to adapt and use the tools of electron microscopy in new ways to transform our understanding of the structure of the materials we work with.”

‘This hasn’t been done before’

Because the Brown Investigator Award supports basic science, Dukovic emphasizes that her new area of research isn’t focused on making an existing device more efficient, but on learning how to control the outcomes of light-driven reactions.

“When we try to use sunlight to make new molecules, like fuels or other useful chemicals, there are a lot of other places where the solar energy can go, (including) unproductive pathways where it can go,” she says. “So, we want to understand what controls whether a pathway is going to productive or unproductive and how to enhance the productive pathways.”

Dukovic and her colleagues will explore the role of the structure of the materials that they’re making in determining these photochemical pathways and how they then we can make materials that have efficient photochemical pathways. Ultimately, she says, this may lead to new solar technologies.

“A lot of the chemical products that we use today, such as fuels or fertilizers or other common chemicals, they’re made in really energy-intensive, polluting ways,” Dukovic says. “We want to find ways to use sunlight to make the chemicals that our society uses more sustainable.”

In her lab, Dukovic and her colleagues make semiconductor nanocrystals, which are tiny, light-emitting particles like quantum dots. They then study what happens after these materials absorb sunlight. Sometimes they couple nanocrystals with catalysts like enzymes or other molecules and then study the movement of electrons through the resulting chemical transformations.

Dukovic’s research relies on electron microscopy, but with a unique approach that combines two main types of it: , which is good for studying biomaterials like cells and proteins, and materials electron microscopy “looking at what each technique can learn from the other field,” Dukovic explains. “How can we use these tools together to learn what we need to learn about the structure of materials?

“We’re using tools from the field that have not been used in this way before, so it’s more high-risk, and the (Brown Investigator Award) gives us more time and resources to figure it out, because this hasn’t been done before.”

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ŷ���ڱ���Ƶ Boulder professor of chemistry recalled as great scientist, teacher, colleague, friend, mentor and lover of the outdoors

Josef Michl, a professor of chemistry at the University of ŷ���ڱ���Ƶ Boulder, passed away May 13 while on a visit to Prague. He was 85.

Colleagues describe him as a great scientist, teacher, colleague, friend and mentor, as well as a valuable member of the ŷ���ڱ���Ƶ Boulder Department of Chemistry. Born in Prague and raised in the former Czechoslovakia, Michl joined the department in 1991.

Michl created fields and set research agendas in chemistry, making seminal contributions in diverse disciplines—including organic and inorganic and materials synthesis photochemistry, laser spectroscopy and magnetic resonance and theoretical and computational chemistry. His scientific legacy will echo for generations, colleaugues say.

ŷ���ڱ���Ƶ Boulder Professer Josef Michl created fields and set research agendas in chemistry, making seminal contributions in diverse disciplines. (Photo: Neuron Foundation)

Equally adept at theoretical and experimental work, Michl was a prolific scientist who published almost 600 articles, held 11 patents and co-authored five books.

He was inducted into the National Academy of Sciences in 1984. Among many other awards he received, he was a member of the American Academy of Arts and Sciences, an honorary member of the Czech Learned Society, a Guggenheim Fellow, a Sloan Fellow and a recipient of the Schrödinger Medal.

He left Czechoslovakia in 1968, completed postdoctoral work with R.S. Becker at the University of Houston, with M. J. S. Dewar at the University of Texas at Austin, with J. Linderberg at Aarhus University, Denmark, and with F. E. Harris at the University of Utah, where he stayed and became a professor in 1975 and served as chairman from 1979-1984.

He held the M. K. Collie-Welch Regents Chair in Chemistry at the University of Texas at Austin from 1986-1990, after which he moved to ŷ���ڱ���Ƶ Boulder. In 2006, he accepted a joint appointment as a research director at the Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Prague.

Michl held close to a hundred visiting professorships and named lectureships; delivered hundreds of invited lectures at institutions and conferences; served on many professional and editorial boards, advisory councils and committees; and organized several international meetings.

Michl cared deeply about the Department of Chemistry and left a generous gift that will fund the Josef and Sara Michl Chair of Chemistry.

“Josef was a true intellectual whose interests were deep and broad,” colleagues say. He was fluent in a dozen or more languages, studied literature and history, loved the outdoors and traveled the world with his wife, Sara. They hiked many of the planet's mountain ranges.

“When in doubt, go up,” he said, applying this principle to life and work. He inspired many colleagues, students and postdocs who will miss his brilliance, humor and sanguine disposition.

Michl is preceded in death by Sara, who passed away in 2018. He survived by his brother, Jenda, son, Jenda, and his grandson, Mason.

Top photo provided to by Josef Michl

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Min Han and Arthur Nozik join a distinguished cohort that includes George Clooney and Jhumpa Lahiri

Min Han, a University of ŷ���ڱ���Ƶ Boulder distinguished professor of molecular, cellular and developmental biology, and Arthur Nozik, a ŷ���ڱ���Ƶ Boulder research professor emeritus of chemistry, have been named s of the American Academy of Arts and Sciences, a cohort that includes Kristine Larson, a ŷ���ڱ���Ƶ Boulder professor emeritus of  aerospace engineering sciences.

The 250 members elected in 2024 “are being recognized for their excellence and invited to uphold the Academy’s mission of engaging across disciplines and divides,” according to an American Academy of Arts and Sciences announcement. The Academy was founded in 1780 to “help a young nation face its challenges through shared purpose, knowledge and ideas.”

The American Academy of Arts and Sciences was founded in 1780 by John Adams, John Hancock and 60 colleagues who "understood that a new republic would require institutions able to gather knowledge and advance learning in service to the public good."

“We honor these artists, scholars, scientists and leaders in the public, non-profit and private sectors for their accomplishments and for the curiosity, creativity and courage required to reach new heights,” noted David Oxtoby, president of the Academy, in the announcement. “We invite these exceptional individuals to join in the Academy’s work to address serious challenges and advance the common good.”

The 2024 cohort also includes actor and producer George Clooney, author Jhumpa Lahiri and Apple CEO Tim Cook.

Han’s research uses Caenorhabditis elegans and mouse models to study diverse biological problems related to animal development, stress response, nutrient sensing and human disease by applying both genetic and biochemical methods.

He and his research colleagues in the Han Lab work to identify and analyze mechanisms by which animals sense the deficiency of specific nutrients, including lipids, nucleotides and micronutrients, and regulate development, reproductivity and food-related behaviors.

Nozik, who also is a senior research fellow emeritus at the National Renewable Energy Laboratory in Golden, has researched the basic phenomena at semiconductor-molecule interfaces and the dynamics of electron relaxation and transfer across these interfaces. The ŷ���ڱ���Ƶ Boulder Renewable and Sustainable Energy Institute’s Nozik Lecture Series is named in his honor.

include Henry Kapteyn, Karolin Luger, Alison Jaggar and Natalie Ahn, among many others. In all, 42 ŷ���ڱ���Ƶ Boulder faculty members have been named American Academy of Arts and Sciences fellows.

Top image: Min Han (left) and Arthur Nozik.

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Researchers Andrés Montoya-Castillo and Julia Moriarty are named U.S. Department of Energy Early Career Researchers, receiving multiyear funding

Two University of ŷ���ڱ���Ƶ Boulder researchers have been selected as U.S. Department of Energy Early Career Research Program scientists, a designation intended to support the next generation of U.S. STEM leaders.

Andrés Montoya-Castillo, an assistant professor in the Department of Chemistry, and Julia Moriarty, an assistant professor in the Department of Atmospheric and Oceanic Sciences and a fellow in the Institute of Arctic and Alpine Research, are among from across the United States whose research spans astrophysics and artificial intelligence to fusion-energy and quantum materials. The 93 scientists will share in $135 million in research funding for projects of up to five years.

“Supporting America’s scientists and researchers early in their careers will ensure the United States remains at the forefront of scientific discovery,” U.S. Secretary of Energy Jennifer M. Granholm states in the awards announcement. “The funding … gives the recipients the resources to find the answers to some of the most complex questions as they establish themselves as experts in their fields.” 

Understanding how molecules dance

Montoya-Castillo’s research is guided, in part, by the need to know which molecules are “going to be good candidates for some technological adventure,” he says. “We need to know how that molecule interacts with light.”

Researcher Andrés Montoya-Castillo studies molecular movement to better understand how they absorb energy.

One of the biggest challenges to understanding molecules is the fact that they don’t stop moving. Far from the static picture on a textbook page, molecules “are always dancing, always jiggling about,” Montoya-Castillo says. “When they jiggle about, sometimes photons or little particles of light that they wouldn’t have been able to absorb, now they can. Or the opposite could be true: They can’t absorb particles we thought they could, because they’re jiggling about, or can’t do it as well.”

Knowing how molecules in liquids and solids absorb light has the potential to support the development of everything from more efficient solar cells to organic semiconductors and biological dyes. But knowing molecules means knowing how they dance, a longtime roadblock in designing materials that maximize energy conversion, say, or enhance quantum computing.

So, Montoya-Castillo and his research group will attack this problem with statistics. “One of deepest aspects of theoretical chemistry is saying, ‘OK, we have a random-looking process. What kind of statistics does this random process follow?” he says. “We’re looking to bridge the randomness to establish a fully predictive simulation.”

The researchers will initially apply their techniques to porphyrins, which are molecules prevalent everywhere on Earth and involved in everything from oxygen transport to energy transfer; they cause the red in blood and the green in plants. Montoya-Castillo notes that porphyrins are ideal for testing the techniques because they are highly tunable and are critical ingredients in natural and artificial energy conversion.

“One of the questions we’re asking is, ‘How do we arrive at design principles to make the next generation of photo catalysts or energy conversion devices, the next generation of quantum computing or quantum sensing?’” he says.

“To do this, we need to achieve two things. The first is realize when our wonderful theories and models are not sufficient to predict and explain the physics that one gets from experiment and generalize our approach. We are doing that by developing the theoretical framework required to predict the spectra of molecules whose constant jiggling makes it difficult to know when they will absorb photons.

“The second is to exploit the current models when they work to give us insight. And fast. To tackle this second challenge, we’re working on being able to exploit experimental data to parameterize the model automatically and use this as a starting point to predict how molecules interact with light. Then we’ll be able to match our predictions to experiment, refine the model and our understanding, and speed up feedback loop of theory-experiment-design, which has traditionally been a very computationally complex and expensive procedure.

He adds that, “One of the final things we’re doing is developing a machine-learning framework to reduce this huge computational cost so we can really accelerate the pathway to tweaking these molecules to get some technological advances going for us.”

Climate change and coastal flooding

For Moriarty, a coast oceanographer by training, the path to her DOE-supported research began with a practical observation: As storms become slower and wetter because of climate change, they are dumping a lot more rain on coastal areas. Couple that with sea level rise caused by climate change, and coastal urban centers are increasingly at risk for floods.

Julia Moriarity, a ŷ���ڱ���Ƶ Boulder researcher, uses process-based and statistical machine-learning modeling to understand how flooding affects coastal areas.

“When urban areas flood, you can have sewage systems flood, water-treatment plants flood, nuclear power plants flood, because all these facilities have to be located near water,” Moriarty says. “So, the question is: when a flood causes polluted water to enter the local waterways, what’s that polluted water’s fate?”

Not only can floods contaminate local waterways by spreading bacterial or even radioactive contaminants into them, but they can unleash a cascade of events in which excess nutrient levels can stimulate harmful algae blooms, reduce oxygen levels in the water and reduce water clarity and quality, sometimes leading to “dead zones.”

Moriarty’s research combines process-based and statistical machine-learning modeling to analyze how floods of coastal infrastructure affect pollutant and nutrient fluxes in local waterways, and their impact on biogeochemical processes. A significant aim is to better understand how extreme floods degrade water quality and which aspects of flooding are predictable and which are not.

“If something’s predictable, it’s a lot easier to plan for it,” Moriarty says.

The research will use Baltimore, Maryland, as a case study, in collaboration with the Baltimore Social-Environmental Collaborative (BSEC) Urban Integrated Field Laboratory. Using data from the climate model, as well as a new Baltimore hydrodynamic-biogeochemistry model, Moriarty and her research team aim to better understand how coastal urban flooding impacts local waterway biogeochemistry in different climate scenarios.

Further, the researchers want to use a combination of machine learning and sensitivity tests of the process-based model they develop to scale up what they learn from local observations in Baltimore to coastal-urban systems worldwide.

“The better we can understand and predict these events, the better we can plan for them,” Moriarty says. “It costs a lot less to mitigate risks in advance of events than to clean them up afterward.”

Top image: Glenn Asakawa/ŷ���ڱ���Ƶ Boulder

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ŷ���ڱ���Ƶ Boulder chemistry researcher Joel Eaves and his co-investigators demonstrate how designing interfaces between organic and inorganic materials can convert low-energy light to high-energy

A new class of materials made from inorganic silicon nanoparticles and a common hydrocarbon molecule has the potential to not only make solar panels more efficient, but to improve certain medical imaging and even enhance night vision goggles.

These materials, created by a National Science Foundation-funded group of researchers including Joel Eaves, a professor in the University of ŷ���ڱ���Ƶ Boulder Department of Chemistry, are detailed in research newly published in

Joining inorganic and organic components is an area of chemistry that hasn’t been widely explored but shows great promise in addressing the need to move photon energies around, Eaves explains.

Theoretical chemist partners with colleagues around the country on research exploring nanotechnology and chemical physics.

“The synthetic ability to design these interfaces between organic molecules and inorganic nanoparticles is so enabling,” Eaves says. “There are a lot of really fundamental things we’d like to do and I don’t know what those big next steps are yet, but the process of turning photons into other photons and photons into chemical fuels is something people have been working on for decades. These new materials may lead us to places we’ve yet to reach in these areas.”

Strengthening electronic bonds

Eaves and his colleagues worked with nanometer-sized silicon particles, also called quantum dots, and anthracene, a type of hydrocarbon often used in producing certain dyes. Typically, the electronic bond between the organic molecules and inorganic silicon dots is weak.

Due to this weak bonding, energy moves across the interface in incoherent hops. Eaves and his research colleagues strengthened the bond between the two dissimilar components to create a single new material whose electronic properties were hybridized and distinct from those of its individual components. This significantly improved the efficiency with which the molecules can convert lower-energy red light to higher-energy blue light—a process called photon up-conversion.

The implications and potential applications of this new material may be far-reaching, Eaves says. For example, it may increase solar cell efficiencies by manipulating the spectrum of light.

Eventually, there also may be potential to enhance light-based medical imaging and treatment. While near-infrared light can penetrate deeply into the body, it doesn’t have the energy to generate the free radicals that high-energy ultraviolet light can. Some cancer treatment uses these ultraviolet-generated free radicals to attack cancer tissue, so there is potential to send energy to a targeted spot in the body up-converting red photons so that they damage and kill cancer cells.

Research shows that strengthening the bond between inorganic silicon nanoparticles and a common hydrocarbon molecule creates a new, more energy-efficient material.

Building capacity in research

Another exciting aspect of this new material is its use of silicon, which is earth-abundant and non-toxic, unlike more conventional nanoparticles that use toxic materials like cadmium or lead—making them unusable for medical applications.

While the silicon dots used in the research were created by co-researcher Lorenzo Mangolini, who leads one of just a handful of labs currently able to make them, “as the barrier to entry becomes lower on these next-level technologies, people figure out how to do things better and we train more people to make these components,” Eaves says. “Over time, there will be more people with the ability and capacity to make these things and more innovation will result.”

Eaves adds that beyond the thrill of tremendous new doors that this research opens is the fundamental joy of scientific discovery: “I’m excited about the fact that we have a new chemistry, we have a new material and that we’ve demonstrated how device performance improves when strengthening one chemical bond. The capability is really exciting, not just for next steps in research but what it means for chemistry.”

Former ŷ���ڱ���Ƶ Boulder researcher R. Peyton Cline, now at NREL in Golden, ŷ���ڱ���Ƶ; Kefu Wang and Ming Lee Tang of the University of Utah; Joseph Schwan and Lorenzo Mangolini of University of California Riverside; and Sean T. Roberts and Jacob M. Strain of the University of Texas Austin also contributed extensively to the research.

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The funding is part of a larger $32.7 million award to 14 colleges meant to improve the performance of emerging commercial and defense systems

The University of ŷ���ڱ���Ƶ Boulder is receiving $1.5 million as part of a larger, multi-year, multi-college award from the Semiconductor Research Corp. (SRC) and the Defense Advanced Research Projects Agency (DARPA) with the goal of improving the performance, efficiency and capabilities of electronic systems for emerging commercial and defense applications. 

To advance that agenda, SRC and DARPA have created a $32.7 million Center for Heterogeneous Integration of Micro Electronic Systems (CHIMES) program, which is being led by Penn State. 

“The global semiconductor industry is projected to become a trillion-dollar industry by 2030—driven primarily by computing, data storage, wireless and automotive applications—which is incredible considering that it took 55 years to reach half a trillion dollars in size and will take less than 10 years to double,” said Madhavan Swaminathan, head of electrical engineering and William E. Leonhard Endowed Chair in Penn State College of Engineering’s School of Electrical Engineering and Computer Science, who will direct the center. 

“Such phenomenal growth requires new and transformative logic, memory and interconnect technologies to overcome the inevitable slowdown of traditional dimensional scaling of semiconductors.”

This is the focus of CHIMES, according to Swaminathan. Fourteen university partners—including the University of ŷ���ڱ���Ƶ Boulder—will collaborate to advance heterogenous integration, the efficient and effective integration and packaging of semiconductor devices, chips and other components.

ŷ���ڱ���Ƶ Chemistry Professor Steven George, expert in surface chemistry, nanotechnology/materials, physical chemistry and renewable energy.

ŷ���ڱ���Ƶ Chemistry Professor Steven George, who will direct CHIMES research in Boulder, said he was excited to learn about the new funding.

“This funding is over a five-year period. This longer period will allow us to do the ‘heavy lifting’ required to tackle some hard problems and develop new areas,” he said. “The five-year period is also better for the graduate students, because this duration overlaps with the timeline for their PhD research.”

CHIMES participants will explore 23 research tasks under four synergistic themes, which include system-driven functional integration and aggregation; monolithic 3D densification and diversification on silicon platform; ultra-dense heterogeneous interconnect and assembly; and materials behavior, synthesis, metrology and reliability.

At ŷ���ڱ���Ƶ Boulder, much of the research will focus on methods to deposit thin films. 

“This new funding from SRC/DARPA Center at Penn State will allow us to continue to develop our work using electrons to enhance thin film processing,” George said. “Our earlier work has demonstrated that electrons can enhance atomic layer deposition (ALD) and facilitate ALD at much lower temperatures than is typical for thermal ALD.  

“We have been able to show earlier that electron-enhanced ALD (EE-ALD) can lower the deposition temperature for materials, such as GaN and Si, from 800 to 1,000 Celsius to less than 100 C. This temperature reduction is critical for semiconductor device fabrication, because high processing temperatures can lead to device failure.”

Additionally, EE-ALD is topographically selective and can facilitate area selective deposition (ASD). George said that is notable because ASD is critical for the fabrication of advanced semiconductor devices that have dimensions less than the limits of photolithography.

This area of research at ŷ���ڱ���Ƶ Boulder ties in well with the research being conducted by Penn State and the other universities, according to George, who noted that CHIMES is focusing on the heterogeneous integration needed for 3D devices. 

“Current devices are largely confined to the 2D plane of the silicon wafer. Future devices will move into the third dimension to continue to provide improved performance, more devices per area and lower cost,” he said. “The previous device developments measured by ‘Moore’s Law’ will continue as device architecture moves into the third dimension.”

Moving into the third dimension means that devices will have many levels, similar to many floors in a building, George explained. 

“How these floors are connected by elevators between the floors and hallways within a floor is a challenge,” he said. “There will also be active devices located on various floors. Having logic and memory close to each other on the same floor or between adjacent floors will speed up device performance.

“My research in CHIMES will focus on the deposition of the interconnecting lines between the floors or in the hallways between the rooms on the floor,” he added. “We will also work on the deposition of some novel materials that are needed to fabricate transistors on the various floors or elevator shafts of the 3D device. My focus is on processing. Others in CHIMES are focused on 3D design and stacking multiple chips on each other to obtain even higher scaling.”

George said the latest funding through CHIMES will allow him to continue research he has been working on for more than a decade.

 

This new funding from SRC/DARPA Center at Penn State will allow us to continue to develop our work using electrons to enhance thin film processing​.”

“Our research on EE-ALD was initiated by DARPA about 10 years ago. At that time, EE-ALD was a ‘pie-in-the-sky’ concept,” he said. With DARPA funding, George said it was possible to build equipment to enhance thin film processing and to demonstrate the technology for semiconductor device fabrication. “Now, as part of CHIMES at Penn State, we are targeting more challenges for this technology. Our research for CHIMES represents the continued development of EE-ALD for new materials and selective deposition of then film growth.”

Penn State’s Swaminathan said a highly multidisciplinary center such as CHIMES “will have a major impact on the future of microelectronic systems, especially as research tasks, themes and, more importantly, team members synergize with international roadmaps.

“Any research output from CHIMES needs to be translational, and capable of moving from the lab to manufacturing,” he added. “Therefore, coordination with national efforts, such as the CHIPS Act and the Microelectronics Manufacturing USA Initiative, is critical.” 

According to Roman Caudillo, Intel-SRC assignee and director of the JUMP 2.0 program, such coordination and collaboration is key to graduating what researchers will learn during the center’s first years into the future for the commercial industry.  

“The DARPA innovation programs, like JUMP 2.0, drive public-private investment for disruptive innovation in microelectronics systems at scale, with the goal of mitigating technology risks and delivering critical future commercial insight and intellectual property,” Caudillo said. 

“The CHIMES proposal and view of the future resonated with the investors on how the future needs to evolve. We’re really excited about this partnership and to see the impact CHIMES will have in the next five years and beyond.”

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