Copper has long been recognized as the most effective metal for converting carbon dioxide (CO 2 ) into valuable multi-carbon products like ethylene and ethanol—key feedstocks for chemicals and fuels. However, under the harsh conditions of CO 2 electrolysis, copper's oxidized states, which are critical for driving carbon-carbon (C–C) coupling, are rapidly reduced to metallic copper, limiting both efficiency and durability.
Now, a team led by Professor Jie Zeng at the University of Science and Technology of China has designed a new catalyst that overcomes this limitation. By decorating copper oxide nanoparticles with tiny islands of cerium oxide (CeO x ), the researchers successfully stabilized the oxidized copper species under strongly reducing potentials, enabling highly efficient and stable CO 2 conversion to C 2+ products.
The presence of oxidized copper is essential for C–C coupling, but it's like trying to keep ice from melting in a hot room—it's inherently unstable under CO 2 reduction conditions. Their CeO x nano-islands acted as nanoscale anchors, preserving the active copper oxidation states where it matters most.
The team synthesized the catalyst using a strong electrostatic adsorption method, resulting in uniform CeO x islands about 4 nanometers in size distributed across the copper surface. Through a combination of operando spectroscopy and theoretical modeling, they confirmed that the CeO x islands not only prevented the reduction of Cu 2+ and Cu + species but also lowered the energy barrier for C–C coupling by stabilizing key reaction intermediates.
In performance tests, the CeO x /CuO catalyst achieved a remarkable faradaic efficiency of 78% for C 2+ products at a current density of −700 mA cm −2 , with ethylene as the dominant product. Even under extended operation, the catalyst maintained over 70% C 2+ efficiency for 110 hours at −100 mA cm −2 —a level of stability rarely seen in copper-based CO 2 reduction systems.
What's particularly exciting is that this design is both active and durable. The CeO x islands enhanced intrinsic activity without sacrificing conductivity, and their inherent stability under reductive conditions prevented degradation.
The study also included an economic analysis showing that using the CeO x /CuO catalyst could significantly lower the costs of carbon capture, electrolysis, and product separation for ethylene production—a promising sign for industrial adoption.
As global efforts to decarbonize intensify, CO 2 electroreduction has emerged as a key technology for closing the carbon cycle. However, many catalysts suffer from low selectivity and short lifetimes. This work demonstrates that careful interface engineering can simultaneously address both challenges.
National Science Review