The CO2<\/sub>\u00a0electrochemical reduction reaction (CO2<\/sub>RR) process has intrigued scientists for decades as a promising way to make fuel and other important compounds. A big breakthrough in the 1980s identified copper as a high-performing catalyst for transforming CO2<\/sub>\u00a0and water into starting ingredients for liquid fuels and chemicals like ethylene and ethanol. Subsequent studies showed that copper contains active sites where electrocatalysis takes place: electrons from the copper surface interact with carbon dioxide and water in a sequence of steps that transform them into products like ethanol fuel and ethylene for plastics. Researchers are investigating ways to tune these active sites to selectively produce specific chemicals, including ethanol, ethylene, and propanol.<\/p>\n But copper\u2019s super-catalytic properties quickly degrade during CO2<\/sub>RR, diminishing its performance over time. Through the years, researchers have looked for ways to prevent this performance loss, but the chemical and physical processes that control this degradation were unclear.<\/p>\n With the Berkeley Lab and SLAC researchers\u2019 study \u2013 published recently in the\u00a0Journal of the American Chemical Society<\/em><\/a>\u00a0\u2013 those processes are less mysterious thanks to an innovative application of scattering and imaging techniques that allowed the researchers to identify and observe two competing mechanisms that drive copper nanoparticles to the brink of degradation in a CO2<\/sub>RR catalyst: particle migration and coalescence (PMC), in which smaller particles combine into larger ones, and Ostwald ripening, where larger particles grow at the expense of smaller particles.<\/p>\n \u201cOur 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,\u201d said Walter Drisdell, a co-corresponding author on the paper who is also a staff scientist in Berkeley Lab\u2019s Chemical Sciences Division and principal investigator with LiSA.<\/p>\n In this study, the researchers used a technique called small angle X-ray scattering (SAXS) at the Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC to track the size and shape distributions of uniformly shaped 7-nanometer copper oxide nanoparticles under various electrical voltages in a custom-designed electrochemical cell with an aqueous electrolyte.<\/p>\n When running the CO2<\/sub>RR reaction for an hour, the researchers found that the PMC process dominates in the first 12 minutes, and then after that, Ostwald ripening takes over. Under the PMC mechanism, the nanoparticles migrate and coalesce into clusters. When the Ostwald ripening process takes over, smaller nanoparticles dissolve and redeposit onto larger nanoparticles, the same process that can create crunchy water crystals in ice cream.<\/p>\n Further analyses in the current study showed that lower voltages, where reactions are slower, trigger the migration and agglomeration of the PMC process \u2013 and larger voltages speed reactions up, increasing the dissolution and redeposition process of Ostwald ripening.<\/p>\n Separate\u00a0in situ<\/em>\u00a0X-ray absorption spectroscopy (XAS) measurements at SSRL show that the copper-oxide nanoparticles reduce to copper metal before restructuring begins, and post-mortem imaging confirmed that the nanoparticles had migrated and formed large agglomerates. The imaging was achieved using advanced electron microscopy techniques at Berkeley Lab\u2019s\u00a0Molecular Foundry<\/a>.<\/p>\n \u201cThese results suggest various mitigation strategies to protect catalysts depending on the desired operating conditions, such as improved support materials to limit PMC, or alloying strategies and physical coatings to slow dissolution and reduce Ostwald ripening,\u201d Drisdell said.<\/p>\n In future studies, Drisdell and team plan to test different protection schemes, and continue working with their LiSA colleagues at Caltech to design catalytic coatings with organic molecules, and test these coatings\u2019 ability to steer CO2<\/sub>RR reactions into producing specific fuels and chemicals.<\/p>\n This work was supported by the DOE Office of Science.<\/p>\n The Molecular Foundry is a DOE Office of Science national user facility at Berkeley Lab.<\/p>\n The Stanford Synchrotron Radiation Lightsource (SSRL) is a DOE Office of Science national user facility at SLAC National Accelerator Laboratory.<\/p>\n ###<\/p>\n Lawrence Berkeley National Laboratory<\/a>\u00a0(Berkeley Lab) is committed to groundbreaking research focused on discovery science and solutions for abundant and reliable energy supplies. The lab\u2019s expertise spans materials, chemistry, physics, biology, earth and environmental science, mathematics, and computing. Researchers from around the world rely on the lab\u2019s world-class scientific facilities for their own pioneering research. Founded in 1931 on the belief that the biggest problems are best addressed by teams, Berkeley Lab and its scientists have been recognized with 16 Nobel Prizes. Berkeley Lab is a multiprogram national laboratory managed by the University of California for the U.S. Department of Energy\u2019s Office of Science.<\/p>\n DOE\u2019s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit\u00a0energy.gov\/science<\/a>.<\/p>\n![\"\"](\"https:\/\/www.fie.undef.edu.ar\/ceptm\/wp-content\/uploads\/2025\/04\/Gallery1_890x665px_XBD-202502-022-001.jpg\")
![\"\"](\"https:\/\/www.fie.undef.edu.ar\/ceptm\/wp-content\/uploads\/2025\/04\/Gallery2_890x665px_XBD-202502-022-005.jpg\")