Facile synthesis of MnCO3 hollow dumbbells and their conversion to manganese oxide

Manganese carbonate (MnCO₃) hollow dumbbells were synthesized via a polyol process. Based on the structural analysis of the samples obtained at different reaction times, a mechanism of nucleation-growth-aggregation-ripening was proposed to account for the formation of the hollow dumbbells. Moreover, the manganese oxide has also been obtained from the MnCO₃ crystals after thermal transformation in laboratory air, and the phase of final product could easily be controlled to be either MnO₂ or Mn₂O₃, simply by altering the calcination conditions. The manganese oxide powder products possessed mesoporosity and essentially preserved the pristine morphology of the MnCO₃ precursor.