Electrocatalytic performance of fluoride- and antimony-doped tin oxide coatings produced on titanium substrates using plasma electrolytic oxidation for the electrochemical degradation of organic contaminants in water

Organic pollutants in wastewater can be electrocatalytically oxidized using inactive-type SnO₂ electrodes. However, traditional methods for preparing doped SnO₂ electrodes suffer from low electrochemical efficiency and short service life, which limit their practical application. This research introduces a novel procedure for the organized fabrication of Ti/SnO₂ electrodes doped with F and Sb through the plasma electrolytic oxidation (PEO) process. The Sb-doped electrode (Ti/SnO₂-Sb) achieved the highest roughness factor (972.43) and outer voltammetric charge (99.55 mC/cm²), indicating a superior electroactive surface area. Indeed, Sb doping resulted in the highest oxygen evolution potential (3.13 V_Ag/AgCl) and the lowest oxide resistance (15.59 Ω cm²), along with appropriate hydrophobic properties. The electrochemical degradation test showed 97.09 % methylene blue (MB) degradation using the Ti/SnO₂-Sb electrode at 10 V over 120 min, which was 2.20 times higher than that of the F-doped electrode. The radical scavenging experiment demonstrated that hydroxyl radicals (OH^o) and superoxide anion radicals (O₂^-o) are the crucial reactive species responsible for the electrocatalytic degradation of MB. The PEO coatings exhibited suitable stability after 20 cycles of MB degradation and a promising service lifetime of 290 h, as evaluated in H₂SO₄ solution.