Understanding the electrocatalysis OER and ORR activity of ultrathin spinel Mn3O4

Abstract

Rapid depletion of non-renewable sources has made us look into possible green energy alternatives to meet energy challenges. Electrocatalytic reactions involving oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) play crucial roles in assisting the derivation of clean forms of energy. Here, we demonstrate that few layers of the manganese oxide: hausmannitene (atomically thin two dimensional (2D-Mn3O4) can be exfoliated from its bulk form hausmannite (Mn3O4). Most significantly, the hausmannitene exhibits catalytic activity towards oxygen reduction and evolution reactions. The hausmannitene has enhanced Mn(III) ions (?65%) compared to its parent structure hausmannite (?31%). The Mn(III) ions in a distorted lattice show the highest catalytic activity towards OER performance with the oxygen electrode activity (?E) of 1.08 eV for hausmannitene. The density functional theory (DFT) calculations, confirmed the presence of both Mn(III) and Mn(II) sites on the (112)-oriented surface of Mn3O4 which are highly active for OER and ORR, having vacant and filled orbitals of lowest and highest energy, respectively. Increased oxidation sites aiding to better performance of 2D structure was theoretically manifested. Therefore, demonstrating that similar mechanisms can be used to explore other 2D oxides as possible efficient stable electrocatalyst substitute for energy conversion.