Light-Induced Hydroxyl Reconstruction in ZnSnGa Layered Double Hydroxide for Selective ROS Modulation toward Complete Mineralization of VOCs

Selective regulation of reactive oxygen species (ROS) is crucial for achieving complete mineralization of volatile organic compounds (VOCs). Here, we report the first structurally distinct ZnSnGa ternary layered double hydroxide (ZnSnGa LDH), where Ga³⁺ serves as a framework cation rather than a dopant. This unique lattice configuration weakens Ga-OH bonds and enables light-driven hydroxyl reconstruction. The resulting detach-vacancy-replenishment cycle continuously generates surface hydroxyl vacancies, exposing unsaturated Ga sites that promote p-p orbital hybridization with O₂. Consequently, O₂ is selectively activated into singlet oxygen (¹O₂), while dissociative hydroxyls are oxidized into ^•OH. In situ spectroscopy, radical trapping, and density functional theory (DFT) reveal that ¹O₂ preferentially attacks benzylic C-H bonds to trigger ring opening, whereas ^•OH accelerates intermediate oxidation. This complementary ROS synergy enables nearly complete toluene degradation (≈100%) with 99.8% mineralization efficiency, high stability (10 cycles), and, critically for practical application, broad humidity tolerance (0-100% RH). Beyond VOC abatement, this work establishes light-driven hydroxyl reconstruction as an intrinsic property of the ternary LDH lattice, offering a generalizable defect-engineering strategy for selective ROS regulation. These findings broaden the LDH compositional space and provide a framework for next-generation photocatalysts for robust environmental remediation.