"Our approach allowed us to explore how the nanoscale size distribution evolves as a function of operating conditions, and to identify two different mechanisms that we can then use to guide our efforts to stabilize these systems and protect them from degradation," said Walter Drisdell, a staff scientist in Berkeley Lab's Chemical Sciences Division and principal investigator with LiSA.
In a breakthrough study conducted in the United States, researchers at Lawrence Berkeley National Laboratory (Berkeley Lab) and SLAC National Accelerator Laboratory have unveiled the fundamental mechanisms that limit the performance of copper catalysts. These catalysts are crucial components in artificial photosynthesis, a process that transforms carbon dioxide and water into valuable fuels and chemicals.
The findings, published in the Journal of the American Chemical Society, offer unprecedented insights into catalyst degradation, a challenge that has puzzled scientists for decades.
Using sophisticated X-ray techniques, the team directly observed how copper nanoparticles change during the catalytic process. They applied small-angle X-ray scattering (SAXS) to gain insights into catalyst degradation. This allowed them to identify and observe two competing mechanisms that drive copper nanoparticles to the brink of degradation in a CO electrochemical reduction reaction (CORR) catalyst: particle migration and coalescence (PMC), and Ostwald ripening.
The researchers found that the PMC process dominates in the first 12 minutes of the CORR reaction, followed by Ostwald ripening. Lower voltages trigger the migration and agglomeration of the PMC process, while larger voltages speed reactions up, increasing the dissolution and redeposition process of Ostwald ripening.
These discoveries suggest various mitigation strategies to protect catalysts. These include improved support materials to limit PMC, or alloying strategies and physical coatings to slow dissolution and reduce Ostwald ripening. Future studies will focus on testing different protection schemes and designing catalytic coatings to steer CORR reactions into producing specific fuels and chemicals.