Preparation And Spectral Properties Of TiO₂-based Nano-Composite System

Due to their chemical stability, nontoxicity, low cost, and some other remarkable physical and chemical properties, Ti O2 materials have found wide applications in many fields including environment protection, gas sensing, energy storage and conversion, and so on. The band gap of Ti O2 lies near the UV on the electromagnetic spectrum(3.2e V for anatase bulk and that of thin films is even larger). This inherent property of Ti O2 curtails the overall efficiency of sunlight as only about 3-5% of total sunlight can generate the photo-induced charge carriers. Therefore this property limited its application in the field of photocatalysis and photo-electric conversion. It is reported that the spectral response range can be extended to visible region, and photocatalytic efficiency of this photocatalyst can be improved through doping.In this paper, the preparing methods of different kinds of Ti O2 based nano-hetero-structures are studied, such as Ti O2/Au, and Ti O2/Au/p-Type semiconductor. And the surface morphology, molecular structure, atom valence state and other photo-electric properties of them are discussed. The main contents are organized as follows:(1) We briefly described the characteristics and applications and research status of nano-materials and Ti O2 nano-semiconductor material at home and abroad. Some optical characteristics and the methods of doping for Ti O2 nano-photocatalysist are discussed.(2) We fabricated the highly ordered Ti O2 nanoarray films on different substrates by using the methods of magnetron sputtering and electrochemical etching, and decorated different amounts of Au nanoparticles onto the top of Ti O2 nanoarray films with the methods of magnetron sputtering and thermal annealing, and deposited different p-type semiconductors with the method of magnetron sputtering. Also, as the decolorization rate of methylene blue under the visible light for a reference, we tested the photocatalytic activity of these structures. Statistics indicates that the sample Ti O2/Au/Cu2 O shows the highest photocatalytic activity. After 360 minutes of irradiation, the degradation rate of simple Ti O2/Au/Cu2 O based on silicon cone substrate reaches to 44%.(3) We obtained a nano-composite with higher photocatalysis efficiency, and analyzed the photo–electrical properties of simples with the aid of field emission scanning electron microscope, Raman spectrum, X-ray photoelectron spectroscopy and other characterization methods. Based on above researches, we also fabricated the Au/Ti O2 nano-composite on the substrate of silicon cone. The spectral properties of surface and interface are also discussed with the help of steady and transient state fluorescence spectroscopy.