Fabrication And Photocatalytic Research On CaIn₂O₄/Fe-TiO₂Composite

In recent years, the energy crisis and environmental pollution have become increasingly prominent. Therefore, photocatalytic technology is highly valued for its potential in solving these problems. TiO2, the representative of traditional photocatalysts, is a kind of wide band gap photocatalyst, which can only absorb UV light (4%energy of the sunlight) and cannot use visible light energy (43%energy of the sunlight). Therefore, development of visible light response photocatalyst has drawn a great attention. However, a single photocatalyst has low photocatalytic activity because of the high charge recombination. To solve this problem, we have fabricated highly efficient and stable CaIn2O4/Fe-TiO2composite photocatalyst.This thesis includes two parts. The first part is a literature review. The second part contains the synthesis, structure characterization and research on photocatalytic properties.The first part is a literature review. Firstly, we introduce the principle of photocatalysis and water splitting based on the semiconductor energy band theory. Then we introduce the application of photocatalyst on wastewater treatment and air purification. After that, a summary on current research status of photocatalysts especially composite photocatalysts is introduced. At last, we introduce the content of this thesis.The second part contains the fabrication, characterization and photocatalytic performance of CaIn2O4/Fe-TiO2composites.Firstly, CaIn2O4and Fe-TiO2were prepared by low temperature combustion method and sol-gel method, respectively. Then, CaIn2O4/Fe-TiO2composites were fabricated by a grinding-annealing method using the former precursors. Structural characterization, photocatalytic performance tests and electrochemical analysis were then performed.TEM/SEM reveals that Fe-TiO2nanoparticles were uniformly deposited onto the surface of CaIn2O4nanorods with a compact contact. However, excess Fe-TiO2nanoparticles cannot deposit on CaIn2O4rods when the mass ratio is higher than0.5. The electrochemical analysis indicates that the conduction band of Fe-TiO2is about0.19V negative to CaIn2O4which means the energy band of the two component match well with each other. CaIn2O4/Fe-TiO2composites show better photocatalytic activity than the single components on MB degradation and hydrogen production. The CF0.5(CaIn2O4: Fe-TiO2=1:0.5) composite shows the greatest photocatalytic property with good stability. Under the visible light irradiation, the CF0.5composite shows a high hydrogen production rate of280μmol h-1g-1. For MB solution degradation,30mg of CF0.5composite can degrade140mL MB solution with21.4μmol/L in3hours. At the same time, CF0.5shows good stability on structure and photocatalytic properties.Two reasons are concluded to explain the enhancement in photocatalytic activity. Firstly, CaIn2O4/Fe-TiO2composites show larger surface area and high absorption in visible region which means more reactive sites and more photo-induced charge carriers. Secondly, the interface between two components in CaIn2O4/Fe-TiO2composites enhanced the charge separation. The electrons could transfer from the conduction band of Fe-TiO2to that of CaIn2O4and the holes could transfer from the valence band of CaIn2O4to that of Fe-TiO2.