In situ Probing of Mn₂O₃ Activation toward Oxygen Electroreduction by the Laser-Induced Current Transient Technique

Electrochemical transformation of Mn4+ into Mn3+ in the Mn2O3 bixbyite structure is believed to activate this oxygen reduction catalyst for O2 electrosorption. The actual mechanism, however, still remains to be revealed and elucidated. This earth-abundant Mn-based material, viz., Mn2O3-rod catalyst, was found to have similar activity to Pt/C (20%) in alkaline media. Intrigued by this observation, an in-depth analysis was performed by combining different electrochemical techniques, including the laser-induced current transient technique. Deeper insights into the structure of the electrical double layer and its properties were obtained by probing the electrode surface with a laser beam to record laser-induced current transients to estimate the potential of zero charge. The synthesized Mn2O3 was further found to be an efficient electrocatalyst alternative to Pt/C (20%), an expensive and limited noble-metal catalyst.