Plasmonic Enhancement Enables Deactivation Resilient TiO ₂ for Sustainable VOCs Remediation under Practical Conditions

ABSTRACT Indoor exposure to volatile organic compounds (VOCs) such as acetaldehyde and toluene poses major health risks, but photocatalytic oxidation over TiO 2 is strongly modulated by humidity and pollutant complexity. Here, we reveal contrasting humidity responses of acetaldehyde and toluene on TiO 2 : acetaldehyde degradation improves under dry conditions, whereas toluene removal requires humid environments to avoid severe deactivation. These divergent behaviors are amplified under mixed‐VOCs feeds, where toluene deactivation suppresses overall mineralization efficiency. Remarkably, plasmonic Au/TiO 2 catalysts exhibit humidity resilient and durable performance, maintaining >70% removal efficiency for both VOCs across RH 25%–80%. Spectroscopic characterizations (XPS, Raman, soft and hard XAS) demonstrate that Au nanoparticles establish strong electronic interactions with TiO 2 facilitating interfacial charge transfer and enhanced ROS generation, while in situ EPR distinguishes the specific formation pathways of • OH, O 2 •− , and h + , demonstrating that plasmonic excitation sustains ROS activity even under conditions where TiO 2 alone becomes inactive. Critically, wavelength‐resolved operando FT‐IR directly shows plasmon excitation selectively accelerates ring‐opening step providing clear evidence of plasmon‐driven regeneration processes. Collectively, these results provide direct mechanistic evidence that plasmonic excitation at the Au/TiO 2 interface sustains VOCs mineralization offering a generalizable strategy to design deactivation resilient photocatalysts for indoor air remediation.