2025 Talented 12: Dayne Swearer

For Dayne Swearer, electrons have power—literally. At Northwestern University, his team uses the kinetic energy carried by “hot” electrons to drive some of the world’s most important industrial chemical reactions. Powered by renewable electricity, this approach could offer a cleaner route to staples like hydrogen and ammonia than traditional thermal processes that depend on fossil fuels.

Swearer’s fascination with science started early: as a kid, he cracked the spine of his encyclopedia from reading it so often. A first-generation college student, he began his studies at Drexel University thinking about pursuing medicine, not realizing that a career in research was possible. But he was soon sold on chemistry. “I switched after getting involved in undergraduate research, knowing that I could make a really big impact in the world,” he says.

He first encountered hot electrons during his PhD studies with Naomi Halas at Rice University, where he worked on plasmonic materials such as metal nanoparticles. When a light wave passes close to one of these nanoparticles, the electrons in the metal move in response to the light’s electric field. “You drive the electrons into this rhythmic kind of oscillation, called plasmon resonance,” Swearer says. The electrons gain so much kinetic energy that they can reach temperatures of 20,000 °C or more.

By using white light to generate hot electrons in aluminum nanocrystals, Swearer and his colleagues at Rice showed that the electrons could be channeled into palladium islands on the nanocrystals’ surface. This helped the palladium catalyze the reaction between acetylene and hydrogen to form ethylene. Crucially, the system produced very little ethane, a common by-product when this process is driven by heat.

Halas’s team called this catalytic combo an “antenna-reactor complex,” with the plasmonic nanoparticle acting as an antenna to harvest energy from light and feeding it to a catalytic reactor site. Halas recalls that Swearer immediately saw the concept’s potential and developed a range of other examples. “As we say in Texas, he jumped on that like white on rice,” she says, laughing. “He was really outstanding, very hardworking. His level of excellence inspired others.”

Halas cofounded a company called Syzygy Plasmonics to exploit antenna-reactor complexes; Swearer’s patented work has already helped Syzygy develop commercial metric-ton-scale reactors that use electric light to liberate hydrogen from methane or ammonia.

After postdoctoral work with Jennifer Dionne at Stanford University, Swearer established his own group at Northwestern in 2022 and returned to targeting those hot electrons in catalytic metals. But rather than corralling the metals into reactive islands, he disperses single catalytic atoms through plasmonic nanoparticles to form dilute alloys—a strategy that could use the catalyst more efficiently. Teaming platinum atoms with a copper host, for example, creates a plasmonic photocatalyst that can convert propane into propene. Illuminating this catalyst within a regular thermal reactor provides a light-driven assist that actually saves energy. “You can get about a 50 °C reduction in operating conditions for the same conversion levels, with good selectivity,” Swearer says.

Some electrical insulators, such as titanium dioxide, can harness light in similar ways. So Swearer has used titanium dioxide nanoparticles to improve the activity of metal catalysts that oxidize carbon monoxide, for example. Metal oxides are often used as supports for traditional catalysts in industry, and Swearer wants to redesign those materials so that they can capture light or microwaves to give those catalytic processes an energy boost.

Recently, Swearer’s group also started investigating low-temperature plasmas: soups of ions, radicals, and electrons that are used in microelectronics manufacturing and water purification. Although cool to the touch, these plasmas teem with hot electrons, and Swearer is deploying them in various catalytic reactions.

Swearer points out that thermal reactions waste a lot of energy making reactants jiggle around in unproductive ways. In contrast, hot electrons can be targeted to activate specific bonds in a more energy-efficient manner. And these systems, powered by electricity, could enable smaller plants that produce chemicals where they’re needed. “I think there's an opportunity to use these kinds of electrified chemical processes to rethink the way that we make and use chemicals on a day-to-day basis,” he says.