Macroporous manganese oxides with regenerative mesopores.

We demonstrate a simple route to making hierarchically porous MnO. Macropores in Mn3O4 are induced through a process of powder sintering. The loss of volume associated with the reduction of Mn3O4 to MnO results in the formation of mesopores in the walls of a macroporous monolith of MnO. The mesopores are regenerative, in that oxidation closes them up and reduction opens them again.