Enhancing the eosin-yellowish dye degradation in drinking water by using TiO2 coatings co-doped with Ni and In

This work reports on the structural, morphological, and photocatalytic properties of titanium dioxide (TiO₂) and TiO₂:NiIn (T-NiIn) coatings fabricated by spin coating. The SEM images revealed coatings with average thicknesses of 3.59 and 3.37 μm for the TiO₂ and T-NiIn, respectively. EDS spectra and Raman studies confirmed the presence of TiO₂ co-doped with nickel (Ni) and indium (In) in the coatings. XRD analysis showed the anatase and rutile phases for the TiO₂ coatings, while the T-NiIn coatings presented the rutile and brookite phases. These samples were evaluated in the photocatalytic degradation of the eosin-yellowish (EY) dye. The T-NiIn coatings showed 9.1% higher effectiveness than the undoped TiO₂ coatings after 300 min under UV irradiation. Meanwhile, the T-NiIn coatings exposed to solar light removed 40% more dye than the TiO₂ coatings. Furthermore, T-NiIn coating was the most stable because its effectiveness was reduced by only 1.4% after 4 cycles of reuse. Additionally, the scavenger tests confirmed that the main oxidizing sites were the •OH^- radicals and the superoxides •O₂^-. Thus, the use of coatings based on TiO₂ co-doped with Ni and In is a feasible strategy to increase the degradation of the EY dye in drinking water.