fig3

Figure 3. Schematic overview of representative two-electron electrocatalytic reactions and mechanisms. (A) Oxygen-related two-electron pathways, including oxygen reduction and water oxidation. (B) Nitrogen-oxyanion reduction through nitrate/nitrite-derived intermediates. (C) CO₂ reduction through representative carboxyl- and formate-type intermediates. (D) Halide oxidation via sequential electron transfer and halogen coupling.