Dopant-Strengthened S-Scheme Heterointerfaces in Mo-TiO2/Sb2S3 Nanotubes Enable Built-In Field-Driven Charge Channels for Efficient Visible-Light Mineralization of Aromatic VOCs.

Efficient photocatalytic mineralization of volatile organic compounds (VOCs) is fundamentally constrained by limited visible-light harvesting, rapid charge recombination, and high kinetic barriers associated with aromatic ring cleavage. Herein, it is reported that a Mo-doped TiO2/Sb2S3 nanotube (Mo-TiO2/Sb2S3) S-scheme heterojunction in which dopant-induced electronic modulation and interfacial built-in electric field (BIEF) engineering operate cooperatively to enable directional charge transport and accelerated oxidation kinetics. Mo incorporation increases the TiO2 work function and amplifies the Fermi-level offset relative to Sb2S3, generating a strengthened BIEF that promotes S-scheme charge transfer while preserving strong redox potentials. Spectroscopic and photoelectrochemical analyses reveal prolonged carrier lifetime, enhanced interfacial charge mobility, and the formation of Ti-S and Mo-S covalent pathways that facilitate rapid electron flow and reactive oxygen species (ROS) generation. Density functional theory (DFT) calculations further demonstrates that Mo doping downshifts the d-band center, strengthens reactant adsorption, and significantly lowers the energy barrier for benzoic acid ring-opening, the rate-determining step in toluene mineralization. As a result, the optimized catalyst achieves nearly complete toluene degradation with high CO2 selectivity under visible light. This work establishes a synergistic strategy combining dopant-induced electronic tuning and S-scheme heterointerface design to overcome kinetic bottlenecks in aromatic VOC mineralization, offering a pathway for advanced air purification.