Facile fabrication of CuO/Cu2O composites with high catalytic performances

The diverse morphologies of CuO/Cu2O composites having good catalytic properties for the reduction of 4-nitrophenol in the presence of NaBH4 have been controlled facilely by adjusting the concentrations of NaOH during the wet etching of Cu2O cubes. The catalytic activity of CuO/Cu2O composites is found to depend highly on their morphologies; in particular, CuO/Cu2O composites prepared at 0.3 M concentration of NaOH(aq) have shown the strongest catalytic performances. Regarding the highest catalytic activity of the composites with cavities surrounded by CuO flakes, the confinement effect is considered to expedite electron transfer from BH4- to the dye molecule enormously by reducing the activation energy largely; the energetically favorable formation of the activated complex at the inner walls of a CuO box lowers the energy barrier substantially. In brief, CuO/Cu2O composites having high catalytic activity have been prepared facilely via a controlled oxidation process of Cu2O cubes, and they may be applied to treat wastewater in an inexpensive way without employing the commonly used noble-metal catalysts.