Fabrication And Property Studies Of Titania Nanosheets Composite Film

A very important factor in photoelectrochemistry solar energy conversion research is the enhancement of solar spectrum's using efficiency. How to enhance the absorbance and widen scope for photoelectric conversion materials is very important not only in researching photophysical or photochemical properties of semiconductor, but also in improving solar cell.Inorganic oxide semiconductor has received widely attention because of its resourceful, steady, non-poisonous, synthesis simple, as well as strong absorbance and anti-photo erode. However, its scope is narrow, especially focuses on UV spectrum with short wavelength and low power. So sensitization is an efficient strategy to widen scope for inorganic oxide semiconductor.If two kinds of inorganic oxide semiconductor nano-materials are combined with each other, which has wide and narrow band-gap respectively, we will find that: for one hand, absorbance spectrum red-shifts and scope is widen based on the construction of electron transition flat in band-gap, but also photo erode and photo aging are resisted, which root in narrow band-gap and organic dyes; for another hand, photo-induced electron can transfer and transit freely between nanosheets because of quantum size effect and quantum tunneling effect, photocurrent is enhanced as well. This paper firstly raised the point of sensitizing the wide band-gap semiconductor with the narrow one, as well as making use of nanosheet material and electrostatic layer-by-layer self-assembly to fabricate photoelectric conversion composite film, then take the electrochemical and photoelectrochemical measurements and discuss composite mechanism. The main contents of the thesis are given as follows:1. The fabrication and exfoliation of layered materials. Layered cesium titanate and MnO₂ are fabricated respectively via high temperature solid-state method and hydrothermal synthesis, and then the layered materials become homogeneous, steady colloidal suspensions via proton exchange, osmotic swelling and exfoliation; while, layered Co/Al-NO₃-LDHs is fabricated by nucleation/crystallization isolated method and exfoliated by formamide.2. Structure characterization and property measurements of titania/MnO₂ nanosheets composite film. The film, assembled by electrostatic layer-by-layer self-assembly method, has layered periodic heterostructure, which are measured by XRD and XPS; Its redox potential, measured via cyclic voltammetry, is useful to construction of electric energy level model; Its photocurrent, measured by chronoamperometry in simulated sunlight, reached 2.22μA·cm^-2, which is 10 times higher than before; Its maximum output power is 1.0714μW·cm^-2 and fill factor is 0.29, which received via linear sweep voltammetry.3. Structure characterization and property measurements of titania and Co/Al-LDH nanosheets composite film. The film, also has layered heterostructure, which is characterized by UV-Vis analysis; Its poor photoelectrochemical proerty is proved by cyclic voltammetry measurements.