Photonic field enhancement and UV shifting via Allium cepa-derived quercetin coupled to Al-doped TiO2 for ultrafast photocatalytic oil degradation in contaminated

Photocatalytic remediation of petroleum hydrocarbon-contaminated soils remains challenging due to TiO₂’s limited solar spectral response and poor light penetration in turbid media. In this study, we present a novel and rationally designed quercetin-Al-TiO₂@SiO₂ aerogel composite that overcomes these limitations through synergistic photonic, plasmonic, and scattering-mitigation strategies. Allium cepa-derived quercetin acts as a bio-photonic converter, absorbing underutilized UV-A (320-400 nm) and re-emitting UV-B (280-320 nm) via Stokes shift, precisely matching the LSPR-enhanced absorption of Al-doped TiO₂. The mesoporous SiO₂ aerogel simultaneously minimizes scattering losses () while enhancing photon residence time (). Our first-principles modeling predicts a significantly improved photocatalytic efficiency, demonstrating a 24-fold enhancement in degradation kinetics (t₁/₂ ∼ 60 min) compared to conventional TiO₂, achieved through optimized ROS generation (10⁵ cm⁻³s⁻¹) and charge separation (). The proposed system also anticipates long-term field deployment, with a photostability-informed quercetin encapsulation strategy, dopant-retention in Al–TiO₂, and aerogel durability supporting reusability. This work demonstrates a new paradigm for solar-driven environmental remediation by integrating biological spectral conversion with engineered plasmonic nanomaterials in a soil-compatible matrix, offering a sustainable solution for large-scale hydrocarbon degradation.