Aqueous Synthesis And Photocatalytical Property Study Of Bismuth Based Micro/nano-materials

Because of their unique physical and chemical properties,bismuth based semiconductor materials are widely used in the fields of optoelectronics,catalysis,information storage and so on.Therefore,controllable synthesis and application of bismuth based semiconductor materials have always been a hot topic for researchers.The photocatalytic properties of the materials are closely related to the morphology,structure,composition and other factors.By controlling the synthesis of highly ac tive bismuth based semiconductors,it is of great significance to its practical application.In this work,a series of bismuth based semiconductor materials with different morphologies and compositions were prepared by a simple liquid precipitation method,including tetrahedral?-Bi₂O₃,Bi nanospheres and BiO₂–_x/Bi nanocomposites.The effects of reaction conditions and growth mechanism were studied.The synthesized materials were applied to photocatalytic degradation of organic materials?such as RhB and BPA?,and the corresponding photocatalytic mechanism was analyzed.First,tetrahedral metastable phase?-Bi₂O₃ was synthesized in aqueous solution with the assistantce of ethylene glycol?EG?.The effects of reaction time,reaction temperature and alkali amou nt on the morphology and structure of the samples were studied.The morphology,structure,optical properties and band structure of the obtained samples were discussed,and the growth mechanism of tetrahedral?-Bi₂O₃was analyzed.In addition,the photocatalytic activity of the prepared?-Bi₂O₃ was studied by degradation of RhB solution under visible light.The photocatalytic mechanism of tetrahedral?-Bi₂O₃ was studied by the capture experiment.Second,uniform size Bi nanospheres were successfully prepare d with the assistantce of sodium molybdate through a wet chemical reaction.The size of Bi nanospheres can be manipulated to some extent by adjusting the amount of sodium molybdate.The experimental results of RhB degradation showed that sample with smaller size exhibited higher photocatalytic degradation rate.Third,a series of BiO₂–_x/Bi nanocomposites were prepared via a time-dependent aqueous method,with the induction of lactic acid.The interaction of Bi³⁺and C₃H₆O₃in stock solution determined the formation of bismuth oxide BiO₂–_x as the precursor,subsequent reduction reaction at acid circumstance?pH=3?produced combined composition of BiO₂–_x nanosheets and Bi particles.Multiple valence states of Bi element(Bi⁰,Bi³⁺and Bi⁵⁺)in the composite sa mple make it possible to manipulate the band structures of photocatalysts.The BiO₂–_x/Bi composites with appropriate composition exhibited superior photocatalytic performance in the degradation of colorless bisphenol A?BPA?under visible-light irradiation.The·O₂^-and·OH radicals were detected as valid active species in the degradation process from ESR analysis.The photocatalytic mechanism over BiO₂–_x/Bi composites was proposed on the consideration of electron–hole separation and the interfacial charge transfer.