Dynamic growth of rhombic dodecahedral Cu2O crystals controlled by reaction temperature and their size-dependent photocatalytic performance

Compared with low-index {100} or {111} planes of Cu2O crystals, rhombic dodecahedra (RD) Cu2O crystals exposing 12 {110} facets exhibit the most superior photodegradation of organic pollutants. Herein, a series of RD Cu2O crystals with different sizes were successfully synthesized by precisely adjusting the reaction temperature ranging from 40 degrees C to 100 degrees C. The results revealed that truncated rhombic dodecahedra (TRD) Cu2O crystals were fabricated when the temperatures was 40 degrees C. More importantly, on raising the temperature to above 40 degrees C, Cu2O architectures dynamically evolved from TRD to RD. Meanwhile, the sizes gradually decreased with elevation of the temperature, while the RD morphology of Cu2O crystals remained, demonstrating the importance of temperature for determining the morphology and size of Cu2O crystals. In addition, we also carefully investigated the visible-light photodegradation performance of Cu2O crystals for methyl orange (MO). RD Cu2O crystals exhibited superior photocatalytic activity compared with TRD, and showed size-dependent photocatalytic activity for MO. The photocatalytic activity of RD Cu2O 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 Cu2O 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 Cu2O crystals.