A surfactant-free solvothermal synthesis of Cu2O microcrystals and their photocatalytic activity.

The Cu2O octahedral microcrystals have been successfully fabricated by a surfactant-free solvothermal approach. The morphology and structure of the as-prepared sample were characterized by scanning electron microscopy, X-ray powder diffraction and UV-Vis spectroscopy. It was found that the structure and morphology of Cu2O microcrystals were strongly affected by synthesis time and temperature. Based on the time-dependent experiment, the possible formation mechanism of Cu2O octahedral microcrystals was proposed. The photocatalytic activities of as-prepared Cu2O samples were also evaluated for degradation of methyl orange under visible-light irradiation. The results showed that the Cu2O synthesized at 180 °C for 4 h had a better photocatalytic performance due to its high percentage of exposed (111) crystal facet and the lowest band gap energy.