Enhanced electro-catalytic activity of TNTs/SnO₂-Sb electrode through the effect mechanism of TNTs architecture

The TiO₂ nanotubes arrays/SnO₂-Sb (TNTs/SnO₂-Sb) electrode is successfully fabricated using the solvothermal synthesis technique. Various architectures of TNTs are constructed by varying the anodization voltage and time, aiming to investigate their impact on the structural and electrochemical properties of the SnO₂-Sb electrode. The anodization voltage is identified as the primary influencing factor on the morphology and surface hydrophilia of TNTs arrays, which is evidenced by scanning electron microscopy (SEM) and contact angle testing. In contrast, the effect of anodization time is relatively small. SEM, X-ray diffraction (XRD), linear sweep voltammograms (LSV), and electrochemical impedance spectroscopy (EIS) results indicate that the morphology and crystal size of the catalytic coating, as well as the oxygen evolution potential of the electrode, are influenced by the pore size of TNTs arrays. The influencing mechanism of enhanced electrochemical activity by adjusting the architecture of TNTs arrays is investigated using X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and hydroxyl radicals (·OH) generation test. The results reveal a higher concentration of oxygen vacancies on the sample with a compact and smaller particle coating, indicating the presence of more adsorbed oxygen species. Consequently, this enhances the generation capacity of active radicals for organic matter degradation. The electrode featuring TNTs arrays with a length of 950 nm and a pore diameter of 100 nm exhibits the most effective remediation of phenol-containing wastewater, achieving approximately 92% ± 4.6% removal after a duration of 2 h.