A study on the synergistic adsorptive and photocatalytic activities of TiO_2-xN_x/Beta composite catalysts under visible light irradiation

A series of TiO_2-xN_x/Beta composite samples were prepared by coating the nitrogen-doped titania on the Beta zeolite using a simple sol-gel method. Samples were characterized by nitrogen adsorption-desorption, XRD, TEM, UV-vis, XPS and FTIR techniques. The photocatalytic activities were evaluated by the degradation of methylene blue under visible light irradiation. The synergistic effect between absorption and photocatalysis of the TiO_2-xN_x/Beta composite materials was found in terms of methylene blue removal efficiency under visible light irradiation, since the assisting adsorption ability from H-Beta zeolite could supply a concentrated pollutant environment around titania active sites. The highest photocatalytic efficiency was obtained on the 10% TiO_2-xN_x-coated composite sample, which was probably due to the better dispersion of titania on the support. Furthermore, the TiO_2-xN_x/Beta-10% catalyst was consistent to be the most efficient composite material tested for the photocatalytic degradation of methylene blue even in different pH environment.