Enhancement of photoresponse to ultraviolet region by coupling perovskite LaMnO3 with TiO2 nanoparticles

Abstract

Mixed oxides of rare-earth elements and 3d transition metal perovskite materials were studied for their catalytic application. We have previously reported the catalytic performance of perovskite LaMnO3 nanoparticles under visible light and ultrasonic irradiation separately and simultaneously. However, LaMnO3 perovskite’s narrow optical gap can absorb only a small portion of the solar spectrum in the ultraviolet region, resulting in low catalytic performance. Coupling LaMnO3 with other metal oxides with an optical gap in the ultraviolet light range offers an effective solution to this problem by improving catalytic performance. To this end, sol-gel was used to prepare LaMnO3/TiO2 nanocomposites with varying LaMnO3 to TiO2 molar ratios. The LaMnO3/TiO2 nanocomposites were characterized using X-ray diffraction (XRD), a vibrating samples magnetometer (VSM), and UV-visible diffuse reflectance spectroscopy (DRS). The anatase phase of TiO2 and the orthorhombic structure of LaMnO3 facilitate the coupling of LaMnO3 with TiO2, and the incorporation of TiO2 nanoparticles tends to increase the optical gap of the nanocomposite. The samples were used to remove organic dyes by means of simultaneous light and ultrasonic irradiation. The results confirm that the photosonocatalytic performance of LaMnO3/TiO2 nanocomposites successfully extends to the ultraviolet light region, and the main factors influencing photosonocatalytic activity are studied and discussed.