Bismuth-Based Oxide Composites Prepared By Solution Combustion Synthesis With Its Photocatalytic Property

Photocatalysis has attracted lots of attention as its environmental,efficient in water pollution treatment.Bismuth-based oxide composites have been reported as photocatalyst candidates for degrading water pollutants and decomposing organix molecules,owing to their wide visible-light absorption range and their ability to generate superoxide/hydroxide radicals under visible light irradiation.Solution combustion synthesis?SCS?,which is self-sustained by its own exothermic reaction,is both energy-and time-efficient and has been for synthesis of nanomaterials and metastable composites.Bismuth-based oxides can be rapid preparation by one-step solution combustion synthesis?SCS?,decorating with nobel metal ion and building the composites between the bismuth-based oxides can furtherly improve its photocatalytic propertis.In the present study,Bi₂O₃ were selectively synthesized via one-step solution combustion synthesis?SCS?using bismuth nitrate?Bi?NO₃?₃·5H₂O?as the oxidant and tartaric acid?C₄H₆O₆?as the fuel.?/?-Bi₂O₃ heterojunction was rapidly prepared by treating SCS?-Bi₂O₃ powders with NaOH solution.AgNO₃ was added into the basic SCS system to obtain the Ag/Bi₅O₇NO₃ composites.In addition,bismuth-based oxide can be compounded with other semi-metal oxides,such as Bi₂Mo₃O₁₂/MoO₃composite system to improve the photocatalytic performance.During SCS,?-and?-phases can be controllable prepared by changing the fuel/oxidizer ratio together with the sintering temperature in SCS and?/?-Bi₂O₃heterojunction was rapidly prepared by treating SCS?-Bi₂O₃ powders with NaOH solution.?-Bi₂O₃,?-Bi₂O₃ and?/?-Bi₂O₃ show good photocatalytic properties in degrading MO,and for?/?-Bi₂O₃,the degrading efficiency achieved 86%in 180 min.Bi₅O₇NO₃ and Ag/Bi₅O₇NO₃ composites,as novel efficient photocatalysts,were synthesized via a one-step solution combustion synthesis?SCS?.The amount of Ag in the composite was tailored by varying the AgNO₃ content during the SCS process.It can be seen in EDS results,Ag particles distribute uniformly on the Bi₅O₇NO₃ sheets.And the crystal face of the Bi₅O₇NO₃ and Ag can be clearly seen in HRTEM results.The Ag decoration improved the Bi₅O₇NO₃ photocatalytic efficiency for methyl orange?MO?degradation,likely owing to the relatively low recombination rates of electrons and holes.The 5 mol%Ag/Bi₅O₇NO₃ composite exhibited the best photocatalytic performance?95%in 60 min?,which was 1.5 times higher than that of pure Bi₅O₇NO₃.In addition,the reactive species O₂^-played an important role in degrading pollutants.Bi₂O₃?MoO₃??-Bi₂Mo₃O₁₂ and Bi₂Mo₃O₁₂/MoO₃ were prepared by SCS using bismuth nitrate?Bi?NO₃?₃·5H₂O?,tartaric acid?C₄H₆O₆?and ammonium molybdate?AHM?as the raw materials.As shown in SEM results,the Bi₂Mo₃O₁₂ particles were decorated on the plate-like MoO₃.Both MoO₃ and?-Bi₂Mo₃O₁₂ show excellent photocatalytic properties over degrading CR,the degradation efficiency of the sample with the AHM/Bi?NO₃?₃ molar ratio was 1/2 could achieve 83%.