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The presence of diclofenac (DCF) in water has developed into a severe environmental problem due to its pernicious effects on animals and human being. Herein, a photoelectrocatalytic (PEC) method using I doped TiO2 (I-TiO2) photoelectrode has been developed, which exhibited excellent visible activity in the degradation of DCF as well as pharmaceutical wastewater. The Langmuir Hinshelwood kinetic model, active species trapping experiments and analysis of intermediate products were employed to analyze the PEC degradation mechanism of DCF. The results revealed that the decomposition of DCF was primarily performed on the photoelectrode (I-TiO2) surface, and the degradation process was accompanied by the dechlorination reaction. The degradation of DCF was caused mainly by holes (66.6%) and hydroxyl radicals (27.6%) when Na2SO4 acted as electrolyte. The degradation rate of DCF could be significantly enhanced under the condition of high Cl− concentration (NaCl acted as electrolyte), which was caused by the participation of chloride radicals (Cl ) in the PEC process. The Cl was the major factor contributing to the decomposition of DCF, and the holes and hydroxyl radicals played a less important role than Cl under this condition.

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 OH) by F and Sn co-doping. The h+ and 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 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 OH). Furthermore, the degradation pathway of phenol was proposed according to intermediates in the PEC process.