Mn5O8 Nanoparticles as Efficient Water Oxidation Catalysts at Neutral pH

Mn 5 O 8 nanoparticles (NPs) were obtained via the controlled oxidation of MnO NPs. The oxygen evolution reaction (OER) properties of Mn 5 O 8 NPs were evaluated using cyclic voltammetry (CV). A current density of 5 mA/cm 2 was reached when 580 mV of overpotential was applied at pH 7.8. Electron paramagnetic resonance (EPR) analysis was conducted to investigate the origin of high OER activity of Mn 5 O 8 NPs. From the EPR analysis, Mn 3+ was found to be involved in the OER process of the Mn 5 O 8 materials.