Middlebury Receives $1 Million DOE Grant to Study How Materials Harness Light Energy

Benjamin Cotts and Alexandria Bredar, assistant professors of chemistry, have received a $1 million grant from the U.S. Department of Energy (DOE) to study how materials use light energy to drive chemical reactions. The research could lead to more efficient ways to produce fuels such as hydrogen.

The four-year grant is part of the DOE’s Established Program to Stimulate Competitive Research (EPSCoR), which supports partnerships between researchers in states such as Vermont and national laboratories. Cotts and Bredar will collaborate with Jihong Ma, assistant professor of mechanical engineering at the University of Vermont, and scientists at Argonne National Laboratory near Chicago. 

The team will use advanced X-ray technology to observe how atoms move within materials after absorbing light. The project will also provide hands-on opportunities for up to eight Middlebury students, some of whom will work alongside scientists at Argonne.

The research focuses on metal oxides, materials with potential applications in solar energy conversion, chemical manufacturing, and pollution reduction. Although promising, they lose much of the light energy they absorb, Cotts explained. One reason is a phenomenon called a polaron, in which an excited electron causes nearby atoms to shift, creating a distortion that traps the electron and prevents its energy from being used in a chemical reaction.

Cotts and Bredar hope to better understand these atomic movements and how they vary depending on the size, composition, and surface characteristics of nanoparticles. Their findings could help scientists design more efficient materials for converting light into chemical energy. 

“We’re working to try to take movies of how the atoms in materials move around when they’re under the conditions they might be in a solar cell or a laser,” said Cotts. “These techniques can help take a movie of what’s happening within that time period to understand why one device works better than another one.”

The movements occur extremely quickly, often within less than a trillionth of a second after a material absorbs light. To capture them, Cotts and his team will use ultrafast X-rays at Argonne’s Advanced Photon Source, one of the nation’s leading facilities for studying materials at the atomic scale. Rather than recording a continuous movie, they will take a series of snapshots at different moments following a pulse of light. By repeating the experiment and assembling the images, they can reconstruct how atoms move over time, a process Cotts likens to creating a flipbook.

The grant builds on a $750,000 DOE grant awarded to Cotts in 2022, using similar experimental techniques but applying them to a new class of materials with potential applications in light-driven chemical reactions. For example, the research could help improve materials that use sunlight to split water into hydrogen and oxygen, producing hydrogen fuel.

Cotts said the research is distinctive in part because it brings sophisticated techniques commonly used in physics and materials science to nanoparticles of particular interest to chemists. “We’re helping translate the cutting-edge technique to a new class of materials that haven’t been studied with it as much,” he said.

For students, the project offers an opportunity to participate in advanced experiments at a national research facility. Under the previous grant, Cotts took five undergraduates to Argonne to work with its specialized X-ray equipment. Researchers are assigned limited blocks of time to conduct experiments, often operating instruments around the clock for several consecutive days. Students work alongside faculty and national laboratory scientists, analyzing data as it comes in and helping determine the next steps.

“It’s an accelerated, condensed research experience for an undergrad,” Cotts said. “I think it’s a unique opportunity for the students to get exposed to these really complex instruments.” He added that even when students work on smaller parts of a project, they gain significant experience working independently.

Several of Cotts’s former students have gone on to pursue doctoral degrees in chemistry. “We have robust research programs across the sciences, with opportunities for students to conduct advanced research and work directly with faculty,” he said. “I think that early exposure inspires students to pursue research at the graduate level.”