Dynamic growth of rhombic dodecahedral Cu(2)O crystals controlled by reaction temperature and their size-dependent photocatalytic performance

Compared with low-index {100} or {111} planes of Cu(2)O crystals, rhombic dodecahedra (RD) Cu(2)O crystals exposing 12 {110} facets exhibit the most superior photodegradation of organic pollutants. Herein, a series of RD Cu(2)O crystals with different sizes were successfully synthesized by precisely adjusting the reaction temperature ranging from 40 °C to 100 °C. The results revealed that truncated rhombic dodecahedra (TRD) Cu(2)O crystals were fabricated when the temperatures was 40 °C. More importantly, on raising the temperature to above 40 °C, Cu(2)O architectures dynamically evolved from TRD to RD. Meanwhile, the sizes gradually decreased with elevation of the temperature, while the RD morphology of Cu(2)O crystals remained, demonstrating the importance of temperature for determining the morphology and size of Cu(2)O crystals. In addition, we also carefully investigated the visible-light photodegradation performance of Cu(2)O crystals for methyl orange (MO). RD Cu(2)O crystals exhibited superior photocatalytic activity compared with TRD, and showed size-dependent photocatalytic activity for MO. The photocatalytic activity of RD Cu(2)O crystals can be greatly improved by decreasing the size. In particular, RD-60 with the minimum size achieved the best photocatalytic properties compared to the other RD and TRD Cu(2)O crystals, and still displayed high photocatalytic efficiency even after three cycles. Such results advance the understanding that temperature modulation serves as an effective means to fabricate RD Cu(2)O crystals.