CeOx nano-islands stabilize copper catalysts boosting CO2 conversion to valuable compounds

Copper has long been recognized as the most effective metal for converting carbon dioxide (CO₂) into valuable multi-carbon products like ethylene and ethanol—key feedstocks for chemicals and fuels. However, under the harsh conditions of CO₂ 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 CO₂ conversion to C₂₊ 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 CO₂ 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 Cu²⁺ 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 C₂₊ 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% C₂₊ efficiency for 110 hours at −100 mA cm⁻²—a level of stability rarely seen in copper-based CO₂ 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, CO₂ 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.