From Cu2(OH)3Cl to nanostructured sisal-like Cu(OH)2 and CuO: Synthesis and characterization

Cu-2(OH)(3)Cl with an average size of 5-10 mu m have been synthesized by a simple hydrothermal reaction with a yield of similar to 100%. After the as-prepared Cu-2(OH)(3)Cl was treated with NaOH solution, the green crystals were converted to blue sisal-like Cu(OH)(2) with needle-like nanorods pointing out radially from the core. These nanorods were about 100-200 nm in diameter and 10 mu m in length. Using the sisal-like Cu(OH)(2) as sacrificial precursor, CuO with a well-preserved morphological feature of the precursor was formed through thermal treatment. The samples were characterized by scanning electron microscopy, energy dispersive X-ray, X-ray diffraction, X-ray photoelectron spectroscopy, BET nitrogen adsorption, and UV-visible absorption spectroscopy. The conversion of the synthesized Cu-2(OH)(3)Cl to sisal-like Cu(OH)(2) was optically visualized and confirmed by corresponding SEM images, and an "etching-and-growing" mechanism was proposed. The results also show that the as-prepared CuO possesses a band gap of 2.27 eV and high specific surface area (75.8 m(2)/g), and its surface is highly rich in O.