Enhanced visible light photoelectrocatalytic degradation of organic contaminants by F and Sn co-doped TiO₂ photoelectrode

The photoelectrocatalytic (PEC) technology has received considerable attention in the degradation of organic pollutants for its high degradation efficiency and cost effectiveness. In this study, we developed a PEC method with F and Sn co-doped TiO₂ (FTS) as photoelectrodes, exhibiting an excellent PEC performance in degradation of phenol and landfill leachate under visible light irradiation and low-bias voltage. The enhanced PEC performance was mainly ascribed to the creation of a great amount of active species (such as h⁺ and [rad]OH) by F and Sn co-doping. The h⁺ and [rad]OH played a dominant role, and the roles of which were not significantly affected by Sn doping in the PEC process. The PEC degradation mechanism of phenol was further investigated by the Langmuir-Hinshelwood kinetic model and the addition of scavengers. The results indicated that the h⁺-created [rad]OH were mainly generated from the adsorbed OH⁻, and phenol was mainly degraded in the state of the ionization (C₆H₅O⁻) by the active species (h⁺ and [rad]OH). Furthermore, the degradation pathway of phenol was proposed according to intermediates in the PEC process.