First-PrinciplesPrediction of Novel Metastable MnO₂ for the Oxygen EvolutionReaction

Manganese dioxide (MnO₂) is a versatile material with numerous polymorphs that holds significant promise in catalysis and energy storage applications. Due to the different connection forms of Mn–O octahedra, the structural diversity of MnO₂ exists in more than 20 crystal forms. Common crystal phases of MnO₂ include traditional crystal phases such as α-MnO₂, β-MnO₂, γ-MnO₂, R-MnO₂. In this work, we employed the particle swarm optimization (PSO) method combined with first-principles calculations to predict 3 kinds of unreported metastable MnO₂ crystals, P2₁/C–1-MnO₂, <i>Pbcn</i>-MnO₂, and P2₁/C–2-MnO₂. We then systematically analyze these 3 structures have lower energy than α-MnO₂ which is widely used and stable in nature and they have better potential application in the electrocatalytic oxygen evolution reaction (OER). Notably, P2₁/C–2-MnO₂ exhibited superior catalytic activity, featuring lower theoretical overpotentials than conventional MnO₂ phases. These findings expand the known polymorphs of MnO₂ and provide valuable insights into their potential in catalysis and energy storage, offering theoretical guidance for future experimental research.