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چکیده
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In this study, novel Sn(Sb)O₂–γMnO₂ composite coatings with tailored compositions (30:70, 50:50, and 70:30 vol.%) were produced on Ti substrates using electrophoretic deposition. The electrocatalytic (EC), photocatalytic (PC), and photo-electrocatalytic (PEC) activity of the electrodes were systematically evaluated by assessing the degradation of methylene blue (MB) in 0.2 M KCl and 0.2 M Na2SO4 solutions, as well as rhodamine B (RhB) in 0.1 M NaOH + 0.1 M KCl solution. Structural and electrochemical characterizations were conducted using various techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, field- emission scanning electron microscope, energy dispersive spectroscopy, UV–Vis diffuse reflectance spectroscopy, cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy. Notably, the Sn:30Mn electrode achieved complete PEC degradation of MB in 0.1 M KCl within 30 min. It also accomplished full PEC degradation of MB in 0.2 M Na2SO4 and RhB in 0.1 M NaOH + 0.1 M KCl within 60 min. The PEC removal efficiency of this electrode significantly improved through the EC process, which was attributed to its high surface roughness, increased electroactive sites, and elevated oxygen evolution potential (OEP = 3.05 V), effectively suppressing undesired side reactions. In contrast, the Sn:70Mn electrode exhibited the highest PC efficiency, achieving 56.1 % degradation of MB in 30 min. This performance was attributed to its narrowed band gap (3.16 eV) and the formation of an effective heterojunction that enhanced charge separation and light absorption. The scavenger test of destructive radicals showed that OH• and SO4•- in Na2SO4 electrolyte and Cl• in KCl electrolyte are the radicals that degrade polluting dyes. Total organic carbon (TOC) measurements indicated EC efficiency at 85.7 % and PC efficiency at 42.7 %. These findings demonstrate the potential of Sn(Sb)O₂–γMnO₂ composites as durable and high-performance catalysts for advanced oxidation processes in wastewater treatment.
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