Surfactant effect on electrochemical behavior of Co–TiO2 nanocomposite coatings

The influence of sodium dodecyl sulfate (SDS) as anionic surfactant and cetyltrimethyl ammonium bromide (CTAB) as cationic surfactant on the morphology, composition, and texture and corrosion behavior of electrodeposited Co–TiO2 coatings was investigated. The polarization test revealed that the coatings deposited from SDS containing solution formed passive layer in low current densities and high positive voltages than coatings deposited in CTAB containing solution. The corrosion resistance of deposited coatings from SDS containing solution was improved in NaOH and H2SO4 solutions than CTAB one. The performed impedance test results in both corrosive media were compatible with the results of polarization test. The coatings deposited with CTAB had grains structure of 62 nm whilst SDS ones showed finer grains around 45 nm, which it was evaluated by XRD analysis and chronoamperometry extrapolation.