| The composite material is made of at least two kinds of different materials by physics or chemistry method. The performance of composite is superior to any kind of single component. Moreover, composite material has special function.Cuprous oxide (Cu2O) is a p-type semiconductor with a direct band gap of 2.0 eV, which offers it important applications in hydrogen production, superconductor, solar cell and negative electrode materials. It also has a potential application in photocatalytic degradation of organic pollutants under visible light. The property and application of Cu2O composite with other semiconductors, i.e, CdS and TiO2 is studied here. The thesis mainly includes two parts. First, Cu2O composes with TiO2 to form composite. The composite was sprayed on glass matrix for the degradation of organic pollutant. Second, Cu2O/CdS composite film was prepared by chemical bath deposition method and its application in solar cell was explored preliminarily.In the first part, TiO2/Cu2O nano composite is prepared by a novel electrochemical method and sprayed on glass matrix. This composite is characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The degradation of methylene blue by using TiO2-Cu2O film under visible light is investigated as well. The results show that during the degradation process, TiO2-Cu2O film generates H2O2, which forms Fenton regent with Fe2+ and EDTA. The degradation efficiency by TiO2-Cu2O film is higher than that for the system of (TiO2 film +Fe2++EDTA) and (Cu2O film+Fe2++EDTA). The degradation mechanism of TiO2-Cu2O nano composite is proposed by the valence band theory. The Ti3+ ion in the TiO2-Cu2O nano composite is detected by X-ray photoelectron spectroscopy (XPS), which is one of the evidences for the proposal.In the second part, Cu2O/CdS thin film was prepared by a chemical bath deposition (CBD) technique. XRD pattern shows that CdS and Cu2O all are cubic crystal structure. The data of XPS are in accordance with the results of XRD pattern of Cu2O/CdS thin film. SEM image shows that the diameter of CdS nanocrystals is about 40-50 nm and Cu2O layer grows on the surface of CdS while filling in the blank between the gains of CdS. The optical transmittance proves the band gap of CdS film is 2.34 eV and that of Cu2O/CdS film is 2.17 eV. The red shiftΔEg is 0.17 eV. The conductivity of Cu2O/CdS film has been measured by four probe method. The result shows the conductivity of Cu2O/CdS film is about 120Ω-1cm-1. The potential application of Cu2O/CdS film in solar cell is also tried. Cu2O/CdS/ZnO/ITO thin film solar cell is prepared on the base of Cu2O/CdS thin film. The current-voltage curves (I-V) of Cu2O/CdS/ZnO/ITO thin film solar cell under sun light illumination shows that the open-circuit voltage is 0.19 V and short-circuit current is 200μA. It proves that there is photo-current. |
