| Abstract: The metallic Cu modified n-p coupled semiconductors Cu/ZnO-TiO2 were prepared by sol-gel method, and their crystal structure, surface composition and absorptivity of UV light were investigated by techniques of DTA-TG, XRD, TEM, BET, TPR, IR and UV-Vis. The results show that the main crystal structure of the coupled-semiconductors is anatase TiO2 with the particle size in the range of 10～16 nm and BET surface area above 80 m2·g-1. In the process of Sol-gel the probability to form ZnO is reduced because of the dilution of Zn2+ with Ti(OC4H9)4. But through the molecular-level contact with TiO2, Zn2+ cations take the places of the O-tetrahedral and O-octahedral centers to partly form Zn2TiO4, and the coupling effects decrease the reflectivity of semiconductors in the wavelength region of 250～400 nm. A photo-exciting mechanism of the semiconductors embedded with metallic Cu was proposed. The Fermi energy of metallic Cu is in the band gap of ZnO and TiO2, so the addition of metallic Cu offers new energy bands to give and receive the photoelectrons, thus expanding the absorption region of the semiconductors to visible light. |
