Nanosecond Laser-Assisted\nFabrication of Photocatalytically\nActive TiO<sub>2</sub> Nanocoatings: Implication in Organic Dyes Degradation

The development of systems capable of efficiently eliminating\norganic\ndyes from wastewater is crucial for the environment. In this context,\nTiO<sub>2</sub>-based photocatalytic systems are of particular interest.\nHowever, the development of eco-friendly and single-step methods for\nthe fabrication of such systems remains a challenge to their practical\nuse. Here, we demonstrate a fabrication approach for a catalytic system\ncomposed of TiO<sub>2</sub> nanocoating created on the surface of\na bulk titanium plate by exposure to a nanosecond laser. The exposure\nconditions affect the relief and phase composition of the nanocoating,\nas revealed by a combination of scanning electron microscopy (SEM),\ncontact profilometry, Raman, High-resolution X-ray photoelectron spectroscopy\n(HR XPS), and grazing incidence X-ray diffraction (GIXRD) methods.\nUsing the GIXRD method, we establish that nanocoatings consist of\na mixture of anatase and rutile grains with sizes of 22.7–24.4\nand 29.8–32.2 nm, respectively. HR XPS analysis demonstrates\nthat changes in the number of pulses per spot modify the anatase surface\ncontent from 40.6 to 70.4%. The samples with a higher anatase content\nexhibit up to 6.3 times higher catalytic activity, which is confirmed\nby methylene blue degradation when exposed to UV light and can be\nrelated to the synergistic effect of the anatase–rutile heterojunction.\nThe reusability of the samples is supported by repeated degradation\nexperiments. The photocatalytic activity of the obtained TiO<sub>2</sub> nanocoatings is improved by Au nanoparticles deposited on their\nsurface by magnetron sputtering. The proposed approach lays the foundation\nfor the application of nanosecond laser-assisted technologies in the\neco-friendly fabrication of catalytic systems.