First-Principles Prediction of Novel Metastable MnO2 for the Oxygen Evolution Reaction

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 alpha-MnO2, beta-MnO2, gamma-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, Pbcn-MnO2, and P21/C-2-MnO2. We then systematically analyze these 3 structures have lower energy than alpha-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.