Fe–Zn–Ti combined systems as photocatalysts for hydroxyl radicals production in sunlight

In this research, we focused on a photocatalyst for hydroxyl radicals (•OH) production in sunlight and proposed to extend TiO₂ photocatalytic capacity to a visible range by combining it with oxides derived from metals such as iron and zinc. The systems were synthesized through the sol-gel method and were characterized by TGA, FTIR-ATR, XRD, Raman, XPS, UV–Vis, and •OH quantification was carried out by disodium terephthalate hydroxylation reaction. Two key annealing temperatures of 400 and 800 °C, were detected by TGA studies. The iron-systems treated at 400 °C show the best balance between •OH production and less degradation effect attributed to staggering bands potentials of α–Fe₂O₃, ZnO, and anatase phases detected by XRD, making them a good option for partial oxidation. On the other hand, the 800 °C treated systems have the worst •OH production due to some phases with narrow bandgap promoting a fast charge carriers recombination.