Under the conditions considered here (cathodic potentials, anoxic electrolyte) CeO2-δ likely forms 𝑣 𝑂 •• , which nitrate (and other oxidizing intermediates such as nitrite) is capable of filling. We note that strong-metal support interactions may also play a role in enhancing activity, modifying the electronic structure (and therefore adsorption properties) of Cu by interaction with the CeO2-δ lattice. Nitrate affinity for catalyst supports Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) provides a qualitative assessment of Δ𝐺 𝑁𝑂 3 -,𝑎𝑑𝑠 for oxide powders used as analogs for the films investigated here. Figure illustrates ATR-FTIR difference spectra for CeO2-δ in 0.1 M