Sol-gel synthesis of La0·05Mg0·95TiO3/SiO2 microspheres for photocatalytic degradation of azophloxine

Abstract

Lanthanum doped MgTiO3 (La–MgTiO3; n(La):n(Mg) = 0.05:0.95) was synthesized using a sol–gel method, and a layer of this material was supported on quartz microspheres to produce La–MgTiO3(x%)/SiO2 microspheres (LMTO(x%)/SiO2; where x% represents the weight fraction of La–MgTiO3 in the microspheres). The crystal size of MgTiO3 decreased from 43.4 nm in La–MgTiO3 to 29.2 nm in LMTO(20 %)/SiO2, and the bandgap energies increased from 3.34 eV (La–MgTiO3) to 3.91 eV (LMTO(20 %)/SiO2). The supported La–MgTiO3 contributed the most to the total surface area of the LMTO(x%)/SiO2 microspheres; further, the specific surface area of the microspheres decreased with decreasing La–MgTiO3 content. The photoluminescence intensity of the microspheres was significantly lower than that of La–MgTiO3. The activity of La–MgTiO3 was enhanced after loading onto the quartz microspheres. The maximum photocatalytic activity was obtained using LMTO(40 %)/SiO2, while the azophloxine degradation efficiency slightly decreased after five reaction cycles.