Synthesis, Characterization, Photo/Electrocatalytic Activity, and Corrosion Behavior of Ag₂S/PANI Composite Layered TiO₂ Nanotubes Coated on Ti Foil

In this study, the photo/electrocatalytic and electrochemical properties of the composite structure formed by coating silver sulfide (Ag₂S) and polyaniline (PANI) on titanium nanotubes are investigated. Titanium nanotubes (TiO₂ NTs) are synthesized on the surface of titanium (Ti) sheets using the anodization method. Ag₂S is deposited on the surface of TiO₂ NTs through the successive ionic layer adsorption and reaction (SILAR) method, while PANI is coated via the chemical oxidative polymerization technique. SEM-EDS, XRD, FTIR, and electrochemical measurements are used to characterize the prepared nanotubes. The corrosion inhibitor performance of TiO₂ NTs is investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDS) measurements. EIS measurements showed that the PANI layer decreased the resistance of the photoanodes, while the Ag₂S coating increased the resistance compared to PANI. It is determined that the semicircles in the Nyquist curves drawn using EIS measurements are formed due to the Warburg resistance in the low-frequency region and the high-frequency region caused by the charge transfer resistance. Corrosion parameters are measured using Tafel fitting curves. Overall, TiO₂ NTs grown by anodization effectively prevented the corrosion of the Ti photoelectrode, and the corrosion rate is calculated at 0.013 mm/year (mpy). In electrocatalytic (EC), photocatalytic (PC), and photoelectrocatalytic (PEC) activity experiments, PANI/Ag₂S/TiO₂ NT photoelectrode removed 13.775%, 37.71%, and 61.075% of methylene blue (MB) within 120 min under UV light irradiation.