VATIS UPDATE Article

Scientists from EPFL, Switzerland, have designed copper nanocrystals that can greatly improve our ability to turn waste carbon dioxide (CO2) into useful hydrocarbons. Led by Prof. Raffaella Buonsanti at EPFL, exploited the ability of colloidal chemistry to produce tunable materials. The researchers synthesized two different sizes of copper nanocrystal spheres (7.5 nm and 27 nm in diameter), and, using the same colloidal chemistry-based method, three different sizes of copper nanocrystal cubes (24 nm, 44 nm, and 63 nm).

Researchers then used the nanocrystals to explore how size and shape of affected the ability of copper to electroreduce CO2 and to steer their reactivity towards different products such as methane or ethylene. They found that within each shape category (sphere or cube), the smaller nanocrystals show higher catalytic activity. But compared to the spheres, the cubic nanocrystals were more intrinsically active.

In addition, the lab found an unexpected trend, where the cubes with 44 nm side length showed an 80% selectivity for carbon products, 50% of which corresponded to ethylene, an important feedstock for petrolchemicals that can be utilized to produce materials like PET. Statistical analysis of surface atom density on the nanocrystals suggests that their edges play a key role for the CO2 reduction reaction. The work has been published in Angewandte Chemie.