Controllable Preparation Of Bismuth Oxide And Related Bismuth-based Photocatalytic Materials And Studies Of Their Photocatalytic Properties

Now the environmental problems have a great impact on our lives. The semiconductor photocatalytic technology is an environmentally friendly way to solve this problem. Bismuth-based semiconductor materials which poss the excellent optical absorption ability, unique electronic structures and excellent photocatalytic degradation properties, have received much attention of the researchers. Due to the relationship between material performance and their structure, this thesis mainly study bismuth semiconductor materials such asα-Bi2O3, β-Bi2O3,δ-Bi2O3, BiON and Bi5O7NO3, with different morphology have been synthesized via facile methods, then discussed their photocatalytic activity under visible light, explored the important influencing factor of morphology in the preparing of photocatalysts.(1)The well-crystalline Bi2O3 columns assembled by highly-aligned microrods could be synthesized from the reaction of bismuth citrate and KOH aqueous solution at room temperature with the assistance of halogen ion like Cl- or Br-, which comes from inorganic salts MX (M= Na+, K+ or NH4+; X= Cl- or Br-) or surfactants CTAX. The possible influencing factors and formation mechanism of columnar α-Bi2O3 microstructures in the presence of halogen ions was discussed in detail by adjusting NaCl concentration, pH values and so on. Asit is negative ions that mainly affects the formation of α-Bi2O3 hierarchitectures.The columnar Bi2O3 hierarchical microstructures prepared by adding NaCl showed the most excellent photocatalytic activity for Rhodamine (RhB) degradation under visible light.(2)Basic bismuth nitrate (Bi6O6(OH)2(NO3)4·2H2O; BiON), α and δ-Bi2O3, or Bi5O7NO3 and β-Bi2O3 were synthesized from Bi(NO3)3·5H2O respectively using a facile solution crystallization route or subsequent calcination process by adjusting growth parameters such as the variety of the bases and solvents. The studies of the photocatalytic activity of the as-prepared compounds indicated that sheetlike δ-Bi2O3 microspheres and Bi5O7NO3 nanoplates exhibited the highest degradation rate for RhB under visible light irradiation owing to their sheet or plate-like morphology, the associated high surface areas, and suitable band gap energy.