Abstract
We systematically investigated the morphology-controlled synthesis of Cu(2)O micro-nano crystals, especially under surfactant-free conditions, targeting a simple, rapid, and morphologically controllable preparation strategy for polyhedral Cu(2)O micro-nano crystals. By systematically investigating the effects of NaOH concentration, types of reducing agents, and copper salt precursors on crystal growth, precise control over the morphology of Cu(2)O crystals under surfactant-free conditions was achieved. This method can rapidly prepare variously faceted Cu(2)O crystals under mild conditions (70 °C, 7 min), including regular polyhedra with low-index facets exposure including cubes, octahedra and rhombic dodecahedra, as well as more complex polyhedra with high-index facets exposure such as 18-faceted, 26-faceted, 50-faceted and 74-faceted crystals. NaOH concentration is found to be the key factor in controlling Cu(2)O crystal morphology: as the concentration of NaOH increases, the morphology of Cu(2)O crystals gradually transforms from cubes that fully expose the {100} faces to regular polyhedra that expose the {110}, {111} faces, and even other high-index faces, ultimately presenting octahedra that fully expose the {111} faces. Additionally, Cu(2)O crystals with unique morphologies such as hollow cubes and 18-faceted with {110} face etched can be obtained by introducing surfactants or prolonging reaction durations. This work provides new insights into the morphology control of Cu(2)O crystals and establishes foundation in acquiring distinct Cu(2)O polyhedra in a facile manner for their application in catalysis, optoelectronics, sensing, and energy conversion fields.