Effect Of Various Metal Oxide Co-catalysts On Photocatalytic Hydrogen Evolution Over Metal Oxide-MWNTs-Eosin Y Photocatalysts

Since 21st century, the increasing shortage of fossil fuels, greenhouse effect and water pollution prompted us to look for a new, clean and renewable energy. Transforming solar energy into hydrogen energy was a good way to solve the energy and environmental problems. The photocatalytic method was a simple and efficient way to achieve this aim. In it, it is vital to prepare a cheap photocatalyst with high photocatalytic activity.In this thesis, Eosin Y molecules were adsorbed on the surface of multi-walled carbon nanotubes (MWNTs) by a simpleπ-πinteractions. Several kinds of oxide-MWNTs-Eosin Y photocatalysts with better visible light catalytic activity were prepared by using the cheap metal oxides as the co-catalysts. In it, Eosin Y as "antenna molecule" can response to the visible light in the solar spectrum. In addition, the effects of various factors on photocatalytic activity of these catalysts were explored, and a possible photocatalytic reaction mechanism was discussed by the electrochemical method. The main contents are listed below:The acidulated MWNTs (MWNTs-COOH) were chosen as the catalyst matrix, CuO as the co-catalyst instead of Pt, and Eosin Y as the sensitizer. In the presence of sacrificial agent, the influences of various factors, including of loading amount of CuO, the type and concentration of sacrificial agent, pH value of the solution, the dosage of Eosin Y and reaction temperature, on the photocatalytic reaction were discussed in detail. Then a possible reaction mechanism was discussed.The complex of CuO and Cr2O3 co-loaded MWNTs-COOH was prepared by soakage and thermal decomposition processes. The activity of hydrogen generation from water reduction over the Eosin Y sensitized CuO and Cr2O3 co-loaded MWNTs photocatalyst under visible light was investigated. The effects of co-loading amount of CuO and Cr2O3, molar ratio of CuO and Cr2O3, concentration of triethanolamine (TEOA), pH value of the solution and the dosage of Eosin Y on this photocatalytic reaction were explored in detail. The results showed that the CuO played a leading role in the CuO/Cr2O3 co-catalyst.Five kinds of metal oxide co-catalysts loaded MWNTs:CuO-MWNTs, NiO-MWNTs, CoO-MWNTs, AgxO-MWNTs and TiO2-MWNTS, were prepared by solvent evaporation and chemical pyrolysis method, electrostatic adsorption and sol-gel methods, and then their photocatalytic activities were compared. The reaction mechanism of the photocatalytic hydrogen evolution was discussed by cyclic voltammetry (CV) and electrochemical impedance method (Eis).