Transition Metal Modified TiO2-Loaded MCM-41 Catalysts for Visible- and UV-Light Driven Photodegradation of Aqueous Organic Pollutants

Abstract

A number of transition metal (Cr, V, Fe, Cu, Mn, Co, Ni, Mo, and La) incorporated MCM-41 mesoporous molecular sieves with Si/Me = 80 have been synthesized by a hydrothermal method. It was demonstrated that the presence of transition metal salts in the gel during synthesis hinders the action of the template, which results in pores of MCM-41 that are not well-formed. These materials were then loaded with TiO2 via the sol−gel method, and the resulting materials were explored for the destruction of 4-chlorophenol in the presence of visible, as well as UV, light. A combination of various physicochemical techniques such as N2 physisorption, O2 chemisorption, X-ray diffraction (XRD), diffuse reflectance UV−vis (DR UV−vis), and temperature program reduction (TPR) were used to characterize the chemical environment of these transition metals in the prepared catalysts. The dispersion of transition metals as determined by O2 chemisorption suggests that they are well dispersed inside the MCM-41 framework, but the disp...