Functionalization Research Of3D Large-sized SiO₂Materials In Photology And Electricity

We studied the preparation of the functional nanomaterials and the research in photology andelectricity in this paper. Due to the strong capillarity and the effects of structure-direction from thenovel SiO2macroporous material, we have obtained the Bi2O3/SiO2and Sn/Bi2O3/SiO2catalystswith a better activity for photo-degradation and the polymer-S-C/SiO2composite macroporouselectrode with a better electrochemical performance. Details of the research as follows:The novel large sized macroporous SiO2material has been prepared by using a3D backbonepolymer as a template through an in situ sol-gel process and a subsequent calcination at hightemperature. This macroporous materials consist of the nanometer-thin layers in the form of3D,with the thickness of layer about20~30nm, the pore sizes in a range of1~2mm, the apparentdensity less than0.2g·cm-3, the specific surface area over130m2·g-1and the porosity above90%.These pore network formed a special microenvironment of dustless space and microgravity, whichprovides favorable conditions for the research of the preparation and functionalization.The Bi2O3/SiO2composite macroporous material was prepared by using a novel SiO2templatethrough in situ hydrolysis of Bi(NO3)3·5H2O and subsequent calcination at high temperature. Thecomposite material was characterized by SEM、XRD、nitrogen adsorption method、PL and UV-Vis. The visible light catalytic properties of the catalysts were evaluated using rhodamine B as theobjective decomposition substance. The result showed that Bi2O3presented in the form ofnanoparticle and beautiful bud shape which deposited on the surface of3D thin layer in the SiO2.The composite material could catalyze rhodamine B efficiently under visible light illumination andexhibited the best catalytic property with the degradation rate up to96%when the Bi2O3loadingamount of was78.2wt.%.The Sn/Bi2O3/SiO2composite materials were obtained by a chemical precipitation, loadingthe Bi2O3and Sn on the channel surface of the SiO2material. The tin-doped bismuth oxide wascharacterized by XPS、XRD、PL and UV-Vis, followed by a study of the influence on crystalstructure and optical characteristics. The visible light catalytic properties of the catalysts wereevaluated using rhodamine B as the objective decomposition substance. The result showed that thephrase transformation of bismuth oxide from γ、β to α can be effectively inhibited by anappropriate tin doping. The composite materials doped with tin have the good absorption capacity of visible light (λ≥420nm) with the expanded visible-light region response. Compared with theBi2O3/SiO2, the photocatalytic activities of Sn/Bi2O3/SiO2were obviously improved. Furthermore,the catalyst exhibited the best catalytic property with the degradation rate up to98%when theSn/Bi is0.02(in molar ratio).The macroporous conducting C/SiO2composite materials was prepared in-situ polymerizationand vacuum pyrolysis in a novel SiO2template, followed by loading the elemental S and thepolymer film on the channel surface to obtain the polymer-S-C/SiO2composite macroporouselectrode with multilayer structure. The structures of samples were characterized by SEM, and thespecific surface area and average thickness of loads were also measured. The macroporouselectrode materials were used as the anode to assemble the li-ion battery. The electrochemicalperformances were studied by electrochemical charge-discharge experiments and impedancespectroscopy. The results show that the alternating current impedance of electrode increasesrapidly and the reverse cycle performance of lithium ion batteries are improved obviously when thethickness of the polymer film increases, which shows that the existence of the polymer film caneffectively inhibit the loss of polysulfide intermediate. The thickness of the polymer film can beadjusted by changing the dosage of the monomer. As the average thickness of the polymer film is8.0nm, the lithium ion battery exhibits the first discharge specific capacity of792mAh·g-1, and itremains635mAh·g-1after50cycles, which shows the best effects.