Heterostructured TiO₂/SiO₂/γ-Fe₂O₃/rGO Coating with Highly Efficient Visible-Light-Induced Self-Cleaning Properties...

A novel nanohybrid composite of TiO₂, SiO₂, γ-Fe₂O₃, and reduced graphene oxide (TiO₂@Si:Fe:rGO) is fabricated by the sol-gel method. The properties of the coated film were examined by structural and self-cleaning analyses using simulated discoloration/soiling and roofing tests. The fabricated transparent TiO₂@Si:Fe:rGO composite showed excellent photoactivity and wettability, behaving well in self-cleaning applications. The addition of SiO₂ improved the crystalline structure and surface hydroxylation of TiO₂ nanoparticles. γ-Fe₂O₃ decreased the recombination rate of e^-/h⁺ pairs, and significantly improved photocatalytic activity under visible light. Moreover, rGO sheets as excellent electron acceptors and transporters also reduced recombination, as well as affected wettability, achieving superhydrophilicity under irradiation. The coated substrate showed excellent resistance to simulated acid rain and significantly preserved the substrate from soiling in roofing tests.