Short-range and long-range order structure of a δ-MnO2 monolayer at pH 10 (dBi10) as derived from PDF, Bragg-rod and Debye equation modeling of HEXS data. The octahedral layer contains 79 at.% Mn4+ and 11 at.% Mn3+ (MnL), and 10% vacancies which for the most part (8%) are capped by an interlayer Mn3+ octahedron (MnIL). The MnIL octahedra share three corners (TCS bonding) with the three surface O atoms surrounding a vacancy, and complete their coordination with three interlayer water molecules. The layer charge deficit created by Mn4+ vacancies and MnL3+ for MnL4+ substitutions is compensated by 8 at.% MnIL3+, 27 at.% Na+ and H+ (not represented). The interlayer also contains water molecules weakly bonded to Na. The microstructure of the nanosheet can be described equally well with a spherical (left) or cylindrical (right) bend.