Facile and time-saving synthesis of octahedral Cu2O crystals by an ethanol-assisted solution method at low temperatures

Abstract

Size-uniform octahedral Cu₂O crystals were synthesized by a facile and time-saving ethanol-assisted solution method at low temperatures. The synthesized products were systematically characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The results show that the amount of ethanol has strong effects on the phase purity and morphology development of the products. By adjusting the amount of ethanol, the morphology of Cu₂O gradually changed from sphere to octahedron. The possible crystal growth processes are proposed. The presence of more oxygen in ethanol is helpful to the formation of octahedral Cu₂O seeds with truncated low index {111} planes. It is suggested that the oriented attachment mechanism plays an important role in the transition from tiny Cu₂O crystals to large octahedral Cu₂O single crystals. The preferential adsorption of ethanol molecules on the Cu₂O {111} facets makes the octahedral Cu₂O more stable.