Boosting charge separation and ROS regulation in S‑scheme WO3/MIL‑100(Fe) heterojunction for efficient photocatalytic toluene degradation

Efficient photocatalytic abatement of volatile organic compounds (VOCs) critically relies on effective separation of photogenerated electron-hole pairs and the generation of reactive oxygen species (ROS). Constructing S-scheme heterojunctions is an effective strategy to promote charge separation while preserving strong redox potentials. Herein, WO 3 /MIL-100(Fe) composites featuring interfacial Fe-O-W bonds were synthesized via a one-pot hydrothermal method for photocatalytic degradation of gaseous toluene. The optimized 15%WO 3 /MIL-100(Fe) heterojunction exhibits a 1.3-fold enhancement in toluene removal efficiency (52.6%) and twice the CO 2 conversion rate relative to pristine MIL-100(Fe), along with enhanced degradation for o-xylene and styrene, demonstrating broad-spectrum applicability. The interfacial internal electric field (IEF) in WO 3 /MIL-100(Fe) promotes efficient charge carrier separation and accelerates electron transfer. The S‑scheme heterojunction directs the reductive electrons in the MIL-100(Fe) conduction band and oxidative holes in the WO 3 valence band to generate superoxide radicals (•O 2 ⁻) and hydroxyl radicals (•OH), respectively, enabling efficient ring opening and deep degradation. Moreover, the load of WO 3 enhances Lewis acidity and introduces additional adsorption sites, strengthening the interaction with toluene. This work highlights the rational design of MOF-based S-scheme heterojunctions for durable volatile organic compound abatement.