Pyrochlore Type Oxides Of Sm <sub> 2 </ Sub> Innbo <sub> 7 </ Sub> Sol - Gel Preparation And Its Photocatalytic Performance Study

In this paper, pyrochlore-type photocatalyst Sm2InNbO7 was successfully synthesized by sol-gel method using Sm(NO3)3,In(NO3)3 and Nb2O5 as raw materials.The effect of the factors in synthesizing procedure on the crystal structure of samples was studied.The photocatalytic degradation of methylyene blue solution over Sm2InNb07 was also investigated.Transparent gel could be obtained on condition that n(EDTA):n(M3+) was 1.1:1, n(EDTA):n(glycol) was 1:2,pH value of solution was 4-6. Sm2InNbO7 powders were prepared by calcining the dried gel.The XRD and SEM analysis indicated that the optimal synthesizing condition was calcined at 850℃for 3 hours.The Sm2InNb07 powder belongs to cubic crystal system with space group Fd3m, and its grain diameter is between 100-1000nm. The BET test indicated that the specific area of Sm2InNb07 was 6.02m/g.The UV-Vis DRS spectrum analysis suggested that Sm2InNbO7 showed obvious Visible light absorption and the wavelengths of absorption edges reach 510nm.The degradation rate of Methylene blue solution under visible light (λ>400nm) was evaluated. The effect of different factors was studied respectively. The optimal results are as following:concentration of catalyst is 2g/L, initial concentration of Methylene blue is 10mg/L, and concentration of H2O2 is 0.128mol/L. Under this condition, the degradation rate of Methylene blue reaches 93.8%,which is higher than that of samples (43.7%) prepared by conventional solid state reaction method.The results of kinetic research indicated that the photocatalytic degradation of methylene blue followed a first-order reaction and could be described by L-H dynamic equation.