OICC Press Journal of Theoretical and Applied Physics 2251-7235 19 4 2025 08 31 Photonic field enhancement and UV shifting via Allium cepa-derived quercetin coupled to Al-doped TiO2 for ultrafast photocatalytic oil degradation in contaminated 10.57647/j.jtap.2025.1904.40 EN Moses Udoisoh Photonics and Solid-State Physics Unit, Department of Physics, Ignatius Ajuru University of Education, Rumuolumeni, Rivers State Nigeria Ubong Bernard Essien Department of Animal and Enviromental Biology, University of Uyo, Akwa Ibom State, Nigeria Chukwuwendu Jeffrey Amaechi Solid State Physics Unit, Department of Physics, Ignatius Ajuru University of Education, Rumuolumeni, Rivers State Nigeria Dibia Victor Okwudiri Department of Physics, Federal College of Education(T), Omoku, Rivers State, Nigeria Oluwatosin Mayowa Olajide Department of Agronomy, William V.S Tubman University, Harper Liberia. Journal Article 2025 08 31 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.