It was shown for the first time that open microcapsules 1–5 μm
in size with Mn3O4 walls and unique morphology are formed
as a result of spraying an aqueous MnSO4 solution onto the
surface of an alkali solution. The walls have a thickness of
80–120 nm and consist of an array of Mn3O4 nanosheets with
a thickness of 2–3 nm, oriented predominantly in the radial
direction towards the center of the microcapsule. There is a
special rim with a height of 100–200 nm around the hole of the
most microcapsules, which can be a kind of ‘ground’ when
fixing such microcapsules on the surface of a substrate in the
process of application by the Langmuir–Schaefer technique.