Synergistic doping and interfacial engineering for tuning surface electronic structure in C@ZnSn LDH toward enhanced photocatalytic oxidation of aromatic VOCs

Layered double hydroxide (LDH) have attracted great attention for photocatalytic oxidation of aromatic VOCs, but their performance is constrained by low charge mobility and insufficient exposure to active sites. Herein, the efficient photocatalytic oxidation of various aromatic VOCs, including toluene, styrene, chlorobenzene and benzene, was tailored via synergistic carbon doping and interface engineering of ZnSn LDH. The strong interfacial interactions between carbon and ZnSn LDH induce local charge redistribution, hence significantly improving light absorption, charge transfer, and the formation of reactive oxygen species (ROS). Moreover, the introduction of carbon increases the surface functional groups, surface defects, and surface area, which collectively facilitated the adsorption and activation of VOCs. Therefore, the optimized 5C@ZnSn exhibited outstanding performance, achieving 73% toluene removal efficiency and 87 ppm CO₂ generation (corresponding to a mineralization rate of 62%) under UV irradiation (10 W, 254 nm) in a continuous-flow plate reactor at an ultra-high weight hourly space velocity (WHSV) of 3,000,000 mL g_cat⁻¹ h⁻¹. This performance was 1.6 times higher than commercial P25. In addition, 5C@ZnSn demonstrated remarkable and stable activity toward the photocatalytic oxidation of other aromatic VOCs, including styrene (84%), chlorobenzene (50%) and benzene (29%), over a 120 min reaction. Further mechanistic studies reveal two distinct oxidation pathways for toluene and chlorobenzene, involving hydrogen abstraction and nucleophilic substitution, respectively. This work provides valuable insights for tuning the charge transport and offers efficient approach to deeply eliminate aromatic VOC pollutants. © 2025 Elsevier B.V.