Preparation of Photocatalyst in Iron Oxide-Titania Solid Solution and Silica System through Two-Liquid Phase Separation

为了<2-x>制备可见光催化剂，本研究采用固相反应法合成了FeO-Fe_2 O_3-TiO_2三元体系的烧结体，并对其晶相进行了分析，考察了铁氧化物-二氧化钛固溶体的电导率和光电化学性能，以寻找作为光催化剂的最佳组成。随着烧成温度的降低和Ti组分含量的增加，晶相由尖晶石型固溶体转变为α相，并进一步转变为假板钛矿型。同时含有尖晶石型固溶体和α相固溶体的样品具有较高的光电流密度。它们的密度随α相类型比例的增加而增加，当α相类型比例超过60%时，密度急剧下降。 ...更多信息 比。烧结性能的降低导致晶界和气孔的增加。在此基础上，尝试了Fe_2O_3-TiO_2-SiO_2三元体系熔体淬冷法制备氧化铁-二氧化钛固溶体光催化剂。所得微晶玻璃具有富SiO_2和富Fe_2O_3-TiO_2相的分相织构。在SiO_2含量不变的情况下，随着Fe组分含量的增加，晶相由α相转变为α相+假板钛矿型，再转变为α相+尖晶石型固溶体，电导率随Fe组分含量的增加而增加。这些结果与上述FeO-Fe_2 O_3-TiO_2三元系的烧成体的结果一致。但是，由于微晶玻璃成分的不均匀性，很难控制其晶相，也很难有选择地浸出其中唯一的富SiO_2相，下一步的研究计划是在均匀样品中更全面地研究晶相与光电流密度的关系，并通过选择最佳制备工艺条件，实现可见光活性光催化剂。少

In this study, the composite materials comprising continuous iron oxide-titania solid solution (Fe_<2-x>Ti_xO_3) phase were prepared by melting and quenching of the fired body in Fe_2O_3-TiO_2-SiO_2 system in order to fabricate a visible-light active photocatalyst.The fired bodies in the FeO-Fe_2O_3-TiO_2 ternary system were synthesized by use of the solid reaction process, and their crystalline phases, electric conductivities and photo-electrochemical properties were examined in order to search the optimum composition of iron oxide-titania solid solution as photocatalyst. The crystalline phase changed from spinel-type solid solution to α-phase type, and further to pseudo-brookite type with the decrease of the firing temperature and the increase of the amount of Ti component. The sample which contained both spinel-type and α-phase type solid solution showed high photocurrent density. Their density once increased with the ratio of α-phase type, and steeply decreased over about 60 % of t … More he ratio. The decrement of the sinter ability of the sample caused the increase of the grain boundaries and voids. As a result, the photo-excited electrons and holes easily were apt to recombine.On the base of above results, the preparation of the photocatalyst comprising iron oxide-titania solid solution was tried by quenching the melt in Fe_2O_3-TiO_2-SiO_2 ternary system. The obtained glass ceramics had the phase separation texture comprising SiO_2 rich and Fe_2O_3-TiO_2 rich phases The relation between crystalline phase and electric conductivity of the obtained glass ceramics was examined. The crystalline phase changed from α-phase type to α-phase + pseudo-brookite types, further to α-phase + spinel type solid solution with the increase of the amount of Fe component at the constant value of SiO_2, and the electric conductivity increased in the same order. These results were good agreement with those of the fired body in above FeO-Fe_2O_3-TiO_2 ternary system. However, it was hard to control the crystalline phase in the obtained glass ceramics because of their inhomogeneity of the compositions, and to leach the only SiO_2 rich phase from them, selectively.The next plan of the study is to investigate the relationship between crystalline phase and photo-current density in the homogeneous sample, more fully, and to achieve the visible light active photocatalyst by selecting the optimum conditions of the preparation process. Less