Design And Synthesis And Properties Of New Perovskite Photocatalyst

A novel series of visible-light-driven photocotalysts LaCo_xTi_1-xO₃(x=0.25, 0.5,0.75) with ABO₃-type perovskite structure were successfully designed and synthesizedby a sol-gel method at relatively low temperature, here the B site is co-occupied by twokinds of metallic ions with +3 valence chemical states. They were characterized bymeans of several testing techniques such as TG-DTA, XRD, XPS, UV-Vis DRS, TEM,BET and photocatalytic activity measurements under the visible-light irradiation (λ＞420nm). The results show that, compared with LaCoO₃ and La₂Ti₂O₇, LaCo_0.5Ti_0.5O₃sample can be obtained at lower temperature. It can be proposed that the chargecompensation effect(CCE) between Co²⁺ and Ti⁴⁺ ions in raw materials make them tendto co-occupy uniformly B site in perovskite both as the forms of +3 valence, which isresponsible for the lower temperature synthesis. The photoabsorption behaviors of aseries of LaCo_xTi_1-xO₃ photocatalysts are related to their band structure, which arethought that the valence band of LaCo_xTi_1-xO₃ samples is composed of O2p orbit, theconduction band is co-made up of Co3d and Ti3d orbits together. This unique energyband structure is responsible for their higher photocatalytic activity under thevisible-light irradiation; and photocatalytic activity of photocatalysts is related to theproportion of two kinds of metals in B site as well as their photoabsorption behaviors invisible light region, the appropriate Co/Ti proportion of two kinds of metals in B site is1:1, i.e. LaCo_0.5Ti_0.5O₃ possesses the highest photocatalytic activity under thevisible-light irradiation.The lower-temperature preparation of this kind of ternary metal complex oxide bya sol-gel method avoids the disadvantages of conventional solid state reaction methodand endues the material with higher surface properties, and this work will be likely toprovide theoretical and experimental groundworks for designedly synthesizing other new-style ABO₃ perovskite structural multifunction materials with their B siteco-occupied by polynary metals.