Large-scale growth and shape evolution of micrometer-sized Cu2O cubes with concave planes via γ-irradiation

Single-crystalline micrometer-sized Cu2O cubes with concave planes were synthesized via γ-irradiation reducing reaction under ambient conditions without any surfactant. Selected area electron diffraction (SAED) investigation reveals that these cubes are single crystals. The powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used to investigate the nucleation and crystal growth process of Cu2O cubes. The UV–vis absorption spectrum is used to estimate the band gap energies of the Cu2O cubes. The band gap of the products calculated from the UV–vis spectrum corresponds to 2.53 eV, which is larger than the direct band gap (2.17 eV) of the bulk Cu2O. Another value of 1.97 eV hints excitonic discrete energy level in forbidden band, arising from the crystal defects of as-prepared Cu2O single crystal.

Graphical abstractSingle-crystalline micrometer-sized Cu2O cubes with concave planes were synthesized through nucleation and anisotropic crystal growth processes via gamma-irradiation under ambient conditions without using any surfactant. Unlike most of other methods, our experiments are carried out under mild conditions, hydrated electrons generated through γ-radiolysis of water act as reducing agent. The band gap of the as-prepared products calculated from the UV–vis spectrum corresponds to 2.53 eV, another value of 1.97 eV hints excitonic discrete energy level in forbidden band of as-prepared Cu2O material.Figure optionsDownload full-size imageDownload as PowerPoint slide