Chemistry Solutions Fueled by the Sun

Every plant on Earth, from the tallest tree to a microscopic algae, is constantly doing chemistry—converting carbon dioxide and water into the energy they need to survive. We all learned about photosynthesis in elementary school, but what if this foundational process in nature could be harnessed for something else entirely: to help solve perhaps the biggest, most complex threat to life on Earth—climate change?

In a number of innovative lab projects, the BC researcher Jier Huang is exploring that possibility. An associate professor of chemistry, Huang is making organic materials inspired by the relationship between the sun and plants. Her materials mimic how plants use light to trigger chemical changes at the cellular level, such as converting carbon dioxide, one of the most prevalent planet-warming greenhouse gases, into one that doesn’t contribute to climate change.

To appreciate Huang’s work, imagine yourself as a student learning for the first time about the chemical elements and particles that make up our world—electrons transferring between molecules, bonds forming and breaking between atoms. For Huang, the most essential concept is catalysis, or a catalyst. As we all remember from chemistry class, that’s any substance that speeds up a reaction without changing itself, like the enzymes in our saliva that convert starch into sugar.  

Huang’s lab in the Schiller Institute for Integrated Science and Society is where she and a team of students are experimenting with different combinations of molecules and catalysts. To describe her lab, she uses the tagline Designed by Chemists. Powered by the Sun. And it’s easy to understand why: She and her students have created a material called a photocatalyst, meaning that it reacts with the sun. In one of their experiments, the photocatalyst is infused with carbon dioxide (CO2), then put in direct sunlight, which begins a chain of events that leads to a chemical reaction. The sun reacts with the material and causes the CO2 to lose an oxygen atom, making carbon monoxide (CO)—a gas that is dangerous to breathe in high quantities indoors but typically diffuses quickly in outdoor environments and doesn’t directly contribute to climate change the same way carbon dioxide does.

Huang’s photocatalysts can be used to create beneficial changes in other substances, too. For instance, if the same photocatalyst is infused with a drop of water, the sunlight can separate the oxygen and hydrogen parts. That resulting hydrogen has the potential to be used in hydrogen fuel technology, which is a cleaner alternative to natural gas. Today, hydrogen requires a lot of electricity to split the water molecules and create hydrogen. But if water could be split with just the sun, as Huang is working on, it would revolutionize hydrogen as a clean energy. “The goal is to make our contribution in solving the energy crisis and climate change,” she said.

Over the course of her career, Huang’s work has been recognized by the National Science Foundation and the US Department of Energy (DOE). She recently received a $400,000 grant from the DOE’s Office of Basic Energy Sciences to refine her design of a photocatalyst called a hybrid covalent organic framework. This material is a porous structure made of crystalline molecules that can efficiently expose to sunlight the reactants, which are the materials that you start with in a chemical reaction, like the carbon dioxide that gets transformed into carbon monoxide.  

To make these reactions—which are invisible to the human eye—happen and understand the chemistry behind them, Huang relies on a tool called ultrafast spectroscopy, which is essentially a laser that she calls the fastest camera in the world. “Our human eyes watch the world, but we chemists use spectroscopy to watch the molecular world,” she said. “In order to measure this event, we need a tool that is faster than the event itself.”

Huang started studying solar energy conversions as a graduate student at Lanzhou University in China, then earned her PhD in physical chemistry at Emory University. From there she joined the Argonne National Laboratory as a postdoctoral scientist. She was later a faculty member at Marquette University in Wisconsin for nine years, before joining Boston College last year as an associate professor and researcher.

In another project here at BC, Huang is collaborating with Earth and Environmental Sciences Assistant Professor Xingchen Wang to extract CO2 from ocean water. Their plan is to develop a system in the lab that uses Huang’s photocatalysts to convert this CO2 into CO. “Professor Huang's expertise in photochemistry and hybrid materials is crucial to this endeavor,” Wang said. Their collaboration transcends the traditional disciplinary boundaries, he added, which has made the project not only possible, “but also a genuinely enjoyable venture.”

Across all her work, and one experiment at a time, Huang’s sun-fueled reactions have the potential to be a part of broader global efforts to reduce carbon dioxide—a must to combat climate change—and pave the way to cleaner energy solutions. Her goal, she said, is nothing less than to keep pushing the boundaries of what’s possible.