Synthesis of cuprous oxide with morphological evolution from truncated octahedral to spherical structures and their size and shape-dependent photocatalytic activities.

In this study, a facile room-temperature solution-chemical route has been developed to synthesize Cu2O crystals with various sizes and morphologies. Adjustment of feeding speed of the aqueous mixture of polyvinyl pyrrolidone (PVP) and ascorbic acid (AA) enables the Cu2O crystal morphology and size evolution. It is also interesting to find that, simple alteration of the feeding speed of AA aqueous solution enables the size of Cu2O crystals evolved, while the morphology of Cu2O crystals keep unchanged. These Cu2O crystals samples were used as photocatalysts for the decomposition of methyl orange (MO) under visible light irradiation. The results show that Cu2O spiny spheres with hierarchical structure exhibited superior photocatalytic activity compared with truncated octahedrons and spheres. In addition, the photocatalytic activity of truncated octahedral Cu2O can be greatly improved by decreasing the size of Cu2O particles. The work demonstrated a novel strategy for the shape and size-controlled synthesis of Cu2O crystals with superior photocatalytic activities.