The direct synthesis of mesoporous structured MnO2/TiO2 nanocomposite:: a novel visible-light active photocatalyst with large pore size

A series of visible-light-driven mesoporous structured MnO2/TiO2 nanocrystal photocatalysts have been synthesized through a modified sol-gel method, and the N-2 adsorption-desorption isotherm confirms that the mesoporous materials possess large pore size (up to 9.2 nm) and a narrow pore size distribution. X-ray powder diffraction (XRD) analyses and complementary x-ray photoelectron spectroscopy (XPS) measurements reveal that the doping of the transition metal Mn inhibits the growth of TiO2 anatase nanocrystals and the Mn species are highly dispersed on the surface of TiO2. The ultraviolet (UV)-vis spectrum demonstrates the excellent adsorption properties of MnO2/TiO2 over the whole region of visible light, which enables this novel photocatalysis material to possess remarkable activity in the photocatalytic degradation of methylene blue under visible light radiation. Moreover, a `coating mechanism' based on the nucleation of titania nanocrystals along with the interaction between the dopant precursors and titania clusters has been suggested.