Nature-Inspired Morphological Control of Manganese Phosphate Materials via Dissolution–Reprecipitation from Large Single-Crystalline Precursors

In this study, the morphologies of manganese phosphate crystals were controlled via a nature-inspired aqueous dissolution–reprecipitation process. Large, single-crystalline Mn(PO3OH)·3H2O precursors ca. 2 mm in size were first obtained from aqueous solutions containing MnCl2, (NH4)2HPO4, and citric acid by evaporation-induced crystal growth. These precursors were subsequently transformed into Mn5(PO3OH)2(PO4)2·4H2O phases by aging at 40–80 °C for 1–3 days in purified water. The macroscopic shape of the precursor crystals was completely maintained upon aging below 60 °C, where densely packed Mn5(PO3OH)2(PO4)2·4H2O nanoplate layers were formed perpendicularly on the surfaces of the remaining Mn(PO3OH)·3H2O precursor crystals.