•-can then undergo direct oxidation at E > -2.17 V vs Ag/AgCl to generate a second equivalent of CO2. Notably, and in contrast to S2O8 2-reduction, the direct oxidation of C2O4 2-at a GC electrode occurs at potentials close to the thermodynamic value (E 0 = 1.2 V) associated with the first electron transfer, eq 11 (Figure , green trace), indicating that reaction (11) is moderately fast on voltammetric timescales.