Morphological Evolution of Cu2O Nanocrystals in an Acid Solution: Stability of Different Crystal Planes

The morphological evolution of uniform Cu (2) O nanocrystals with different morphologies in a weak acetic acid solution (pH = 3. 5) has been studied for cubic, octahedral, rhombic dodecahedral, 100 truncated octahedral, and 110 truncated octahedral nanocrystals. Cu (2) O nanocrystals undergo oxidative dissolution in weak acid solution, but their morphological changes depend on the exposed crystal planes. We found that the stability of Cu (2) O crystal planes in weak acid solution follows the order of 100 ≫ 111 > 110 and determines how the morphology of Cu (2) O nanocrystals evolves. The stable 100 crystal planes remain, and new 100 facets form at the expense of the less stable 111 and 110 crystal planes on the surface of Cu (2) O nanocrystals. Density functional theory calculations reveal that the Cu-O bond on Cu (2) O (100) surface has the shortest bond length. These results clearly exemplify that the morphology of inorganic crystals will evolve with the change of local chemical environment, shedding light on fundamentally understanding the morphological evolution of natural minerals and providing novel insights into the geomimetic synthesis of inorganic materials in the laboratory.