A concept for electrochemical CO2 •-generation for small molecule activation at a low electrode potential is found in the literature describing co-reactant electrogenerated chemiluminescence (ECL). Briefly, a seminal work by Bard and co-workers utilized the oxidation of rubrene in the presence of C2O4 2-(the co-reactant) to generate ECL. The oxidation of rubrene to the rubrene radical cation at E ≈ 0.4 V vs Fc/Fc + results in homogeneous oxidation of C2O4 to CO2 •-, which is capable of reducing rubrene to the rubrene radical anion (E ≈ -1.7 V vs Fc/Fc + ). Electron-transfer between the radical cation and radical anion of rubrene yields excited state rubrene that emits a photon.