The Synthesis And Properties Exploration On Bismuth-based Catalysts

The photocatalytic technology came into our eyes because of the worsening envi ronment and energy shortages.With photocatalysis technology rapidly developing,it is of increasing importance to exploit visible light activated photocatalysts with high photocatalytic activities.Bismuth-based semiconductors contain p-block Bi3+ ions with a formal ns2np0 electronic configuration,which is responsible for its high charge liquidity.In this thesis,based on a comprehensive review of the publications and current issues concerning bismuth-based semiconductors,we take the representative Bi2Sn2O7 semiconductors as research objects to prove the fact that Bi 6s orbit contributes to good catalytic properties for Bismuth-radiele nanostruc ture oxides.In summary,We designed and synthesized several kinds of bismuth-based catalysts and the photocatalytic performance of these photocatalysts has also been investigated.The main results can be summarized as follows:(1)A series of(Bi2-δYs)Sn2O7 solid solutions were prepared by a one-step hydrothermal method to investigate the correlation between the electronic structures and photocatalytic activity.The contribution of Bi 6s orbit to electronic structures of(Bi2-δYδ)Sn2O7 solid solutions can be continuously tuned by Y3+ substitution for Bi3+.Finally,we applied decomposition of 2-naphthol with assist of density function theory calculations to prove the high photocatalytic activity of Bi-related compounds and the high charge liquidity in Bi 6s orbit.(2)We prepared different morphologies of Bi2O3 by one-step solvothermal method by adjusting the ratio of reaction solvent.Furthermore,the Bi @ Bi2O3 heterojunction structure was fabricated via in situ reduction method.The selective reduction reaction of nitrobenzenes into azobenzene was applied as performance test to explore catalytic properties of Bi @ Bi2O3 porous nanospheres.It is found that the catalytic properties of the Bi @ Bi2O3 porous nanometer spherical is significantly better than Bi2O3.(3)We synthesized the Bi @SiO2 core-shell structure by two-step method and also prove that SiO2 can effectively inhibit the agglomeration and oxidation of Bi nanoparticles.Firstly,uniform morphology of Bi2O3 nanoparticles were synthesized by solvent thermal method.Then,Bi2O3 nanoparticles were formed into collosol to further synthesize the Bi2O3 @ SiO2 by the TEOS hydrolysis under the alkaline conditions.Finally,the Bi2O3 @ SiO2 were reduced into Bi @ SiO2 by in situ reduction method.Furthermore,the in-situ formed Bi @ SiO2 core-shell structure can highly achieve the reduction reaction of nitrobenzenes into anilines.