Si[O.sub.2]-Ti[O.sub.2] Films Supported on Ignimbrite by Spray Coating for the Photocatalytic Degradation of N[O.sub.x] Gas and Methyl Orange Dye

In this work, a Si[O.sub.2]-Ti[O.sub.2] coating, composed of different numbers of Ti[O.sub.2] and Si[O.sub.2] layers, was fabricated by a spray-coating technique. The films were deposited onto ignimbrite rock and divided into two groups according to the number of Si[O.sub.2] layers applied, 10 and 15 layers of Si[O.sub.2] and 5 layers of Ti[O.sub.2] for each group. The morphology and chemical composition of the synthesized samples were characterized by field emission scanning electron microscopy (FE-SEM) and energy dispersive X- ray spectrometer (EDS), which reveal the successful Si[O.sub.2]-Ti[O.sub.2] coating on ignimbrite. The photocatalytic activities of samples obtained were evaluated toward the decomposition of 3 ppm of methyl orange (MO). Finally, N[O.sub.x] gas degradation was studied. The obtained results evidenced that the Si[O.sub.2] and Ti[O.sub.2] coating improved the photocatalytic activity of ignimbrite.