Role of SiO_x interlayer in the electrochemical degradation of Amaranth dye using SS/PbO₂ anodes

Highlights: • A larger amount of oxygen in SiO_x interlayer induces a better nucleation of the β-PbO₂ form. • The hydrophobic character of PbO₂ surface is related to the fraction of oxygen used to deposit SiO_x interlayer. • Remarkable degradation ability of PbO₂ electrode with inorganic SiO_x interlayer. A novel SS (Stainless steel)/SiO_x/PbO₂ anode for dye removal in water electrolysis was studied. SiO_x interlayer was deposited by plasma enhanced chemical vapor deposition (PECVD) in plasma fed with argon, oxygen and tetraethoxysilane (TEOS) in different ratios. Lead oxide was deposited by pulsed electrodeposition. Well-adherent and homogeneous SiO_x film, characterized by high hydrophobicity, were deposited in oxygen rich plasma onto the SS substrate as confirmed by the morphological characterization performed by means of Field Emission Scanning Electron Microscopy (FESEM). The composition of PbO₂ layer was investigated by X-ray diffractometry (XRD) and evidenced that β-PbO₂ crystallites nucleation was promoted by the SiO_x interlayer. Additionally, Electrochemical Impedance Spectroscopy (EIS) measurements were performed for assessing the electrochemical behaviour of the SS/SiO_x/PbO₂ anodes. Results confirmed that the increase in the presence of the β-PbO₂ form, increases the conductivity of the PbO₂ film. Finally, the anode, with SiO_x interlayer deposited in oxygen rich plasma, showed the best efficiency in removing the azoic dye from aqueous solution in terms of COD and color removal.