Spatial geometric effect driven by the different [MnO6] octahedra entity stacking configurations to facilitate the catalytic decomposition of H2O2 in wastewater

Abstract

Achieving rapid decomposition of H2O2 is crucial for broadening its applications across various fields, as improper disposal or leakage can lead to serious water pollution. In this work, we explore how the octahedral coordination entity [MnO6] stacking configurations in different MnO2 polymorphs (α-, β-, γ- and δ-) affect their catalytic performance towards H2O2 decomposition. Combining experiments and theoretical simulations, we find that the catalytic activity for H2O2 decomposition strongly depends on the [MnO6] stacking configurations, following the order of δ- < α- < γ- < β-MnO2. δ-MnO2 displays edge-sharing octahedral stacking in a layered structure and thus exhibits the highest catalytic activity, efficiently decomposing H2O2 (0.5 M) in just 2 min at 25 °C without excessive energy consumption. Theoretical calculations further show that the superior active sites are located at the edge Mn-site of its 2D layered structure, with the rate-determining step of H2O desorption (0.55 eV). This study provides crucial insights into the impact of coordination entity stacking configurations on the catalytic activity differences.