Facile synthesis of plate-like TiO2-SiO2-FeOx nanocomposites for efficient singlet oxygen dominated Fenton-like reactions under dark conditions

Abstract

Heterogeneous Fenton-like catalysis using iron-based materials offers advantages over homogeneous systems in the removal of persistent organic pollutants from water, but it faces challenges such as nanoparticle aggregation. Herein, a mild, alkali-metal-free route is established to synthesize plate-like titanium dioxide-silicon dioxide (TiO₂-SiO₂) nanocomposites with in-situ loaded iron oxides (FeO_x) via an ammonia-mediated hydrothermal process. The formation of the plate-like morphology is attributed to the combined effects of SiO₂ incorporation and acetylacetone chelation. The optimized composite (TSF-1) exhibits significantly enhanced catalytic activity in the dark Fenton-like degradation of organic pollutants. Specifically, TSF-1 achieved an outstanding RhB degradation efficiency of 100% at an initial pH of 3.0 within 60 min, whereas the pristine TS support showed a minimal degradation efficiency of only 19.3%. This superior performance is attributed to its large specific surface area and the abundant surface-active sites (such as Ti³⁺ and Fe²⁺). Notably, our results strongly support a non-radical pathway primarily driven by singlet oxygen (¹O₂) rather than conventional hydroxyl radicals (•OH). We propose that this non-radical pathway is driven by synergistic interactions, where FeOx domains likely act as the primary hydrogen peroxide (H₂O₂) activation sites, while the TiO₂-SiO₂ support facilitates ≡ Fe(II) regeneration and effectively converts generated •OH radicals into ¹O₂.