ZHAOWei ^1,2, GUO Jingjing ^1,2, RONG Jiacheng ^1,2, WANG Hugang ^1,2, ZHANG Qi ^1,2, WANG Heng ^1,2, YANG Xianfeng ³

(1. School of Materials Science and Engineering, Tianjin Chengjian University, Tianjin 300384, China; 2. Tianjin Key Laboratory of Building Green Functional Materials, Tianjin 300384, China; 3. College of Materials Science and Engineering, Changsha University of Science and Technology, Changsha 410114, Hunan, China)

Abstract: Bismuth titanate microspheres were prepared by using hydrothermal reaction and soft chemistry transformation with TiO₂ microspheres as both templates and reactants and Bi(OH)₃ as the source of bismuth. By adjusting the hydrothermal process parameters and combining with XRD and other characterization methods, the formation mechanisms of different crystal phases were clarified. It was found that the mineralizer concentration, Bi/Ti molar ratio, hydrothermal reaction temperature and post-heat treatment temperature all played important roles in determining morphology of the crystals. High concentration of KOH mineralizer and high molar ratio of Bi/Ti were favorable for the formation of the Bi₁₂TiO₂₀, while high hydrothermal reaction temperature resulted in the formation of Bi₄Ti₃O₁₂. The optimal parameters included hydrothermal reaction temperature of 140 ℃, reaction time of 12 h, KOH concentration of 1.0 mol/L, Bi/Ti molar ratio of 1︰3 and heat treatment temperature of 750 ℃, which led to Bi₄Ti₃O₁₂ with a band gap of 3.0 eV, exhibiting excellent photocatalytic degradation performances.
Key words: soft chemistry; Bi₄Ti₃O₁₂; Bi₁₂TiO₂₀; photocatalytic