Advancements in SnO₂-modified electrodes for electrochemical oxidation of persistent organic pollutants: Mechanisms, challenges, and opportunities

The treatment of industrial wastewater contaminated with persistent organic pollutants (POPs) remains a critical global challenge due to their strong resistance to conventional degradation methods. Electrochemical oxidation (EO) has emerged as a promising technology for the effective removal of POPs, particularly with the use of advanced electrode materials. Among them, tin oxide (SnO₂)-modified electrodes stand out for their high conductivity and stability, which significantly enhance EO performance. Further improvements can be achieved through doping with inorganic, metallic, non-metallic, or rare earth elements. These dopants have been shown to increase electrocatalytic activity by inducing oxygen vacancies, modifying surface chemistry, and facilitating the generation of hydroxyl radical (•OH), all of which contribute to more efficient POPs degradation. This review summarizes recent advances in fabrication methods, doping strategies, mechanistic insights into the role of different dopants, and operational approaches. It also addresses key challenges, including the complexity of fabrication, the potential formation of secondary pollutants, and cost constraints. Finally, future directions are highlighted, with emphasis on the development of low-cost dopants, optimization of EO operational parameters, and integrated reactor design strategies to further enhance the performance of SnO₂-based electrodes, advancing the evolution in electrochemical technologies for environmental remediation.