Syntheses of Nano/Submicrostructured Metal Oxides with All Polar Surfaces Exposed via a Molten Salt Route

In this paper, a general method for the preparation of metal oxides with all polar surfaces exposed is presented. The syntheses of the products were carried out with simply performing reactions in a molten salt system, in which cations and anions tend to have strong electrostatic interactions with positive or negative charged polar planes so as to lower the surface energy and slow down the growth rate of polar planes, resulting in the formation of exposed polar surfaces. With this strategy, wurtzite structured ZnO, rocksalt structured MgO, spinel structured Co3O4, and ternary element compound ZnFe2O4 of spinel structure were successfully synthesized with all polar surfaces exposed, which demonstrated a universality of our proposed strategy.