Facile synthesis of Cu₂O nanocubes in triblock copolymer solutions

Cuprous oxide and related materials in nanosizes are of much interest and investigated extensively recently. It is reported here that cubic Cu ₂O nanocubes were synthesized successfully in aqueous solutions at room temperature in air condition. Copper (II) salts in water were reduced with ascorbate acid in air, using the nonionic pluronic amphiphilic triblock copolymer EO₂₀PO₇₀EO₂₀ (P123) as the template-directing and protecting agent. The average edge length of the cubes varied from 50 to 100 nm. Transmission electron microscopy (TEM) has been used for the shape and structural characterization of the obtained Cu₂O nanocubes. The UV-Vis spectra showed an obvious blue-shift (0.53 eV), compared to the band gap of the bulk Cu₂O crystal, which makes it a promising candidate in solar energy conversion since this sample can make use of higher energy visible rays of solar spectrum. In the FT-IR spectra the peak of Cu-O bond for the Cu₂O is clearly distinguished and several weak peaks of the C-H, C-C and C=O bonds for the organic species can also be detectable, implying a little P123 residua in the products. The effect of the triblock copolymer P123 on the growth of the Cu₂O nanocubes is discussed.