Insights to photo-excitated H₂O₂ activation in heterogeneous aerogel with asymmetric defect-engineering for PPCPs...

Photo-Fenton process produces reactive oxygen species (ROS) capable of degrading organic compounds across diverse chemical environments. However, the challenge of coupling multifunctional modules limited the attentions, which are supposed to be paid on intertwined physicochemical processes in porous heterogeneous aerogel. This study elucidated the hitherto neglected synergistic mechanisms of photo-excitated H₂O₂ activation through photon-harvesting and localized surface plasmon resonance (LSPR) effect enhanced by defective sites (coordinatively unsaturated sites (CUS) and oxygen vacancy (V_O)). Fukui index combined with in-situ spectroscopic techniques clarified that the dissociation of piperazinyl, facilitated by photo-generated holes (h_ph⁺) with direct electron trapping properties (activation energy reduction was 72.36 kJ/mol), served as prerequisite of nucleophilic and electrophilic ROS (·O₂^-, ·OH and ¹O₂) to collectively achieve 97.24 % total organic carbon (TOC) removal. Finite-difference time-domain simulations confirmed the prepared porous heterogeneous aerogel exhibited broadband photon-harvesting (300-900 nm) and LSPR effect evidenced by 3.8-fold electric field intensity. Electronic localization function (ELF), Mossbauer and fluorescence spectroscopy revealed CUS and V_O induced asymmetrical electronic configuration of μ₃OFeO₆, elevating d-band center to enhance H₂O₂ affinity. This work might insightfully bridge critical knowledge gaps between nanoscale charge dynamics and macroscopic catalytic performance, opening new opportunities for the development of advanced water purification technology.