Shape-controlled synthesis of Mn2O3 hollow structures and their catalytic properties

A series of MnCO3 and MnC2O4 microstructures were fabricated via a self-templated method, in which carbon spheres obtained by a carbonization process in the same solution served as cores and templates. The shape of carbon@MnCO3/MnC2O4 evolved from rhombi, to ellipsoids, to dumbbells, and to twinsphere particles, depending on the setting time and temperature of the pre-mixing period. The carbon core was completely removed after calcination at 550 degrees C, and a phase transformation to Mn2O3 hollow microstructures was achieved, retaining their original shapes. The catalytic activities of the as-obtained Mn2O3 hollow microstructures for CO oxidation were examined. The catalytic activities decreased in the order of Mn2O3 ellipsoids approximate to dumbbells > twin spheres > rhombi.