A Cluster Model DFT Study for Oxygen Reduction Reactions

The equilibrium (reversible) potential for oxygen reduction reaction (ORR) on Pt electrodes was evaluated using small cluster models and DFT calculations. For the five elementary reactions, O 2 → OOH, OOH → O + H 2 O, OOH → HOOH, O → OH, and OH → H 2 O, the estimated equilibrium potentials were 0.41, 1.99, -0.35, 1.36, and -0.01V. Comparing to the standard electrode potential for O 2 reduction, 1.23 V, the OOH and H 2 O formations contribute to the overpotential, and HOOH formation does not prevail.