Fabrication Of Thin Films Of Nano-semiconductors At Gas/Liquid Interface And Their Photoelectrochemical Performances

In recent years, thin films of nano-scale semiconductor photoelectric materials have attracted wide attention because their wide applications in photoelectrochemical solar cells, hydrogen production from water-splitting, optoelectronics, optics, biomedicine, and so on. In this thesis, we fabricated thin films of Bi2O3/Bi2S3nanocomposite semiconductors, thin films of CdS or TiO2nanoparticles at gas/liquid interface, and studied their photoelectrochemical properties and photoelectrochemical hydrogen production. The main research contents are as follows:1. Fabrication of thin films of Bi2O3/Bi2S3nanocomposite semiconductors at gas/liquid interface. The films were prepared rapidly at gas/liquid interface for the first time by contacting an acidic Bi(NO3)3solution with vapors from ammonia water and ammonium sulfide solution. The influence of contact manner and contact times of the vapors on the photoelectrochemical performance was investigated. The prepared thin films of nano-semiconductors displayed better photoelectrochemical performance than the single Bi2O3and Bi2S3films and the reason was discussed.2. Fabrication of thin films of CdS semiconductor nanoparticles at gas/liquid interface. Thin films of CdS nanoparticles were prepared rapidly at gas/liquid interface by dropping ethanol solution of Na2S at the surface of CdCl2solution with the help of a surfactant (dodecyl sulfate). We also studied the effect of different sacrificial agents on the photoelectrochemical performance and photoelectrochemical hydrogen production for the CdS film. Black Cd/Cd(OH)2/CdS nanocomposites formed in the CdS film when it was illustrated by visible light in a solution containing methanol and sodium hydroxide, and the black nanocomposites benefit to improve the photoelectrochemical performance.3. Fabrication of thin films of TiO2nanoparticles at gas/liquid interface. Thin films of TiO2nanofilms were prepared rapidly at gas/liquid interface by dropping ethanol solution of tetraisopropyl titanate at the surface of deionized water with the help of a surfactant (dodecyl sulfate) at certain temperature. The effect of temperature and film thickness on the photoelectrochemical performances was investigated. The fluorine-doped tin oxide and TiO2nanofilms became black by cathodic polarization, which was beneficial to photoelectrochemical performances.