Photocatalytic degradation of aqueous methyl orange using nanotitania loaded Mo-MCM-41

Nanocrystalline titanium dioxide, TiO₂, is a well studied and commonly used material for photocatalytic applications. However, the control of particle size, monodispersity, large catalytic surface for sufficient adsorption of organic pollutants, recovery and recycle of TiO₂ nanoparticles are challenging tasks. Hence in this work, titania has been introduced into the nanopores (210 nm size) of MCM-41 to produce stable nanoparticles of uniform size and shape. Further, the photocatalytic efficiency can be improved by lengthening the life time of the excited electrons/holes during photoreaction. This could be achieved by incorporating molybdenum in to the MCM-41 silica matrix in addition to titania loading. In the present study, the synthesis and the photocatlaytic efficiency of a new photocatalyst TiO₂@Mo-MCM-41 (25 wt.% TiO₂ loaded Mo incorporated MCM-41) are reported. Mo-MCM-41, with different ratios of Si to Mo (Si/Mo = 25,50,75), is synthesized by hydrothermal method and loaded with 25 wt.% TiO₂ using solgel method. The photocatalytic activity of the prepared samples was evaluated using methyl orange as a model organic compound. X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and nitrogen adsorptiondesorption isotherm (BET analysis) measurements were used to investigate the effects of the incorporated elements in the structure of MCM-41. It was found that the photodegradation ability of 25% TiO₂ loaded Mo-MCM-41 was highly related to the amount of Mo atoms present in the sample with the optimum atomic ratio of Si to Mo being 50.