(654a) Controllable Solution Combustion Synthesis of Nanoscale α/β-Bi2O3 and Its Catalytic Application

Among the four different polymorphs of bismuth trioxide, α- and β- Bi₂O₃ show unique physical and chemical properties . In the present work, Bi₂O₃ nanoparticles of different phases (α and β) were selectively synthesized via simple, rapid and energy efficient solution combustion synthesis (SCS). Bismuth nitrate was used as the oxidizer, while tartaric acid, glycine, EDTA and sucrose were employed as fuels. By changing types of fuels, ratios of fuel/oxidizer and heating temperature, specific phases (α and β) of Bi₂O₃ were controlled and particle sizes (5-50 nm) of these materials were tailored. The formation mechanism was proposed by thermodynamic calculations. Stable α-Bi₂O₃ forms when the combustion temperature is higher than 350 °C while metastable β-Bi₂O₃ forms at temperature lower than 300 °C. Using the SCS products as catalytic supports, series of Pt/SCS-Bi₂O₃ catalysts were prepared and tested for glycerol oxidation. These results were compared to our prior studies of Pt-Bi catalysts placed on activated carbon and other supports.