Research On The Photoelectric And Photocatalytic Properties Of ZnO-based Nano Arrays

Semiconductor materials have been used as photo-catalysts to solve current energy and environmental problems by using abundant solar energy. In recent years, the application of semiconductor photocatalysis has received extensive attention in the field of science and engineering. For example, because of the special electronic structure with a filled valence band and an empty conduction band,semiconductors such as TiO₂, ZnO, CdS, and ZnS were used as sensitizers in light-reduced redox processes, dye-sensitized solar cells and photo-splitting of water to produce hydrogen gas. But most of them are mainly limited by their poor photocatalytic efficiency in the visible light range. With a direct band-gap of 3.37 eV and a large exciton binding energy of 60 meV, ZnO has been widely used for energy harvesting, sensing, piezoelectric transducers, optical waveguides, opto-electronic, and photocatalytic applications under UV and natural sunlight illumination owing to its nontoxicity, low cost, good electrical and optical properties, and efficient photoactivity.Unfortunately, because of the large band gap（3.37 eV） and rapid recombination of photo-generated carriers, ZnO can only absorb and utilize photons in the UV region（makes up only 3⁵% of the total solar spectrum） and have a low photoelectric conversion efficiency.Therefore, it is important to extend its visible-light response and improve the separation and transportation of photogenerated electron–hole pairs.The details are summarized briefly as follows:1 We prepared well aligned hexagon ZnO nanorod arrays using simple hydrothermal synthesis method. Relative test results shows that the ZnO nanorod with an average width of about 200 nm and a length of 1-2 μm. We discussed the mechanism of formation of ZnO nanorod arrays and point out the direction for future research.2 Au modified ZnO nanorod array with special space structure was prepared successfully by a simple and effective light reduction deposition method. Morphology characterization shows that Au nanoparticles were deposited on the surface of ZnO nanorods and adjacent ZnO nanorods are crisscrossed by Au nanowires. Photoelectric performance test results show that the photoelectrochemical performance of Au modified ZnO nanorod arrays has been greatly improved. And the mechanism of improved performance was also analyzed.3 We demonstrate a facile and effective strategy for in-situ growth of Bi₂MoO₆ nanosheets on the well-aligned ZnO nanowires to construct novel hierarchical hetero-arrays, which exhibit excellent visible-light driven photoelectrochemical performances attributed to the highly efficient charge separation between Bi₂MoO₆ nanosheets and ZnO nanowires.