Bioinspired Oxygen-Evolution\nReaction: Achieving Oxygen-Evolution\nReaction on Layered Manganese-Oxide Surface with Extremely Low Overpotential

Despite the common belief that manganese (hydr)oxides\nin the absence\nof other metal ions require high overpotential to catalyze the oxygen-evolution\nreaction (OER) in alkaline conditions, our study has uncovered surprising\nresults. Layered manganese oxide demonstrates noteworthy OER activity\nat the Mn(III) to Mn(IV) oxidation peak following charge accumulation.\nThis activity is achieved with remarkably low overpotential (120 mV)\nin a 1.0 M KOH solution. Initially, the Faraday efficiency is a modest\n20%, which can be attributed to initial charge storage. However, as\nthe reaction continues (200 s), the efficiency significantly increases\nto over 80%. We also propose a detailed mechanism for OER in this\nlow-overpotential regime, supported by in situ visible and Raman spectroscopies\nof the Mn(III) to Mn(IV) peak and the surrounding OER region. By examining\nthe amount of oxygen generated and the concentrations of redox-active\nMn ions near the redox peak, a turnover frequency of 3.8 × 10<sup>–3</sup> s<sup>–1</sup> at 1.35 V was calculated. The\nreduced overpotential observed during the OER can be attributed to\nthe complex interplay between the OER process and charge accumulation\nas it was observed in nature, with these factors collectively enabling\na notably low overpotential. These findings provide significant insights\nfor the design and development of highly efficient and stable electrocatalysts\nfor OER in water-splitting applications, potentially revolutionizing\napproaches to energy conversion and storage. Our findings have significant\nimplications for the development of highly efficient and stable electrocatalysts\nfor OER in water-splitting applications.