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

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 °C to 100 °C. The results revealed that truncated rhombic dodecahedra (TRD) Cu₂O crystals were fabricated when the temperatures was 40 °C. More importantly, on raising the temperature to above 40 °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.