Catalytic carbon dioxide (CO₂) reduction is an important technology for the production of fuels and chemicals. Mechanistic studies have suggested that both electro- and photocatalytic approaches may share a common intermediate: a carbon dioxide radical anion (CO₂^–) bound to the catalyst’s surface.

Now, using rapid-scan Fourier-transformed infrared spectroscopy in combination with isotopic labelling, Heinz Frei, a senior scientist in Molecular Biophysics and Integrated Bioimaging (MBIB), and colleagues have identified a carbon dioxide dimer radical anion (C₂O₄^–) as the crucial surface intermediate during the photocatalytic reduction of CO₂ on copper nanoparticles.

Although recent electrochemical investigations have suggested the existence of this one-electron surface intermediate, this study, published in the Journal of the American Chemical Society (JACS), provides the first direct experimental evidence.

Read more in this Nature Catalysis research highlight.