With the (101) basal plane termination of the Mn3O4 membranes confirmed from XRD and HAADF-STEM (Figures and), we used DFT calculations to investigate the energetics of different surface terminations. Figure shows a visualization of the atomic model of Mn3O4 with colored polyhedra viewed along the [010] direction with the [101] direction pointing up. Here, MnO6 octahedra and MnO4 tetrahedra are shaded dark blue and light teal, respectively. There are two possible oxygen-terminated surfaces of Mn3O4 perpendicular to the [101] direction. One termination involves octahedrally coordinated Mn atoms, and the other involves a combination of tetrahedrally and octahedrally coordinated Mn atoms with the tetrahedrally coordinated atoms closest to the surface. We refer to these surface terminations as the octahedral and tetrahedral surfaces, respectively (see Figure ). We have additionally considered Mn-terminated surfaces.