Morphology Evolution of Cu₂O from Octahedra to Hollow Structures

Octahedral Cu₂O crystals with an edge length about 1 μm were synthesized by reducing a copper-citrate complex with glucose. The morphology and structure of Cu₂O particles were greatly affected by the concentration of glucose, reaction temperature, and time. When the concentration of glucose increased from 0.6 to 1.6 M, the morphology of Cu₂O could be changed from octahedral single crystals to spherical polycrystals. When the reaction time was prolonged from 6 to 36 h, solid Cu₂O octahedra could be changed to a mixture of hollow Cu₂O octahedra and irregular Cu particles. After removing Cu particles, pure Cu₂O hollow octahedra could be obtained. The formation mechanism of hollow Cu₂O octahedra was discussed. Similarly, hollow Cu₂O spheres could also be obtained using this method. The prepared hollow octahedral Cu₂O particles exhibited a higher photocatalytic activity for photodegradation of p-nitrophenol aqueous solution under visible-light illumination than other Cu₂O particles with different morphologies (hollow spheres, solid octahedra, and solid spheres).