One-step fabrication and photocatalytic performance of sea urchin-like CuO/ZnO heterostructures

Sea urchin-like hierarchical p-CuO/n-ZnO heterostructures were fabricated through a one-step chemical bath deposition method without any surfactant or heat treatment. The morphologies and crystal structures of the obtained CuO/ZnO heterostructures were characterized by various characterization methods. The crystal structure of the ZnO nanomaterial is the wurtzite hexagonal structure, while the two main crystal planes of CuO correspond to the (111) and (1&cmb.macr;11), respectively. The samples with a lower dripping rate and longer growth time have the advantages of regular morphology and high porosity. Meanwhile, the photocatalytic performances of sea urchin-like hierarchical p-CuO/n-ZnO heterostructures with different CuO contents were systematically evaluated. As an important p-type narrow band gap (∼1.7 eV) semiconductor, CuO forms a p-n heterojunction with ZnO, which is beneficial to the photocatalytic efficiency of the wide-band gap semiconductor ZnO. The photocatalytic performances of the CuO/ZnO heterostructures increased with increasing CuO content from 0 to 10%. However, when the content of CuO in the CuO/ZnO heterostructure was 20%, it was possible that the concentration of copper oxide is too high, which made the sample agglomerate. Alternatively, excessive CuO will shield ZnO from UV absorption, thus reducing the efficiency of photon utilization. Therefore, when the content of CuO is too high, the photocatalytic performance decreases. For all CuO/ZnO nanocomposites, UV-vis indicates that the 10% ZnO/CuO nanostructure may exhibit higher light utilization. p-CuO/n-ZnO heterostructures with a sea urchin-like hierarchical structure exhibit outstanding photodegradation abilities toward MO under UV light.