Corrosion mitigation ability of differently synthesized polypyrrole (PPy-FeCl3 & PPy-APS) conductive polymers modified with Na2MoO4 on mild steel in 3.5% NaCl solution: Comparative study and optimization

Optimized Anticorrosion of Polypyrrole Coating by Inverted-Electrode Strategy: Experimental and Molecular Dynamics Investigations

“…High conductivity renders the favorable anodic protection effect of conductive coatings for the underlying metal [ 18 , 29 , 30 ]. Shahryari et al [ 31 ] also reported that PPy could convert the metal surface into the passivated state. In addition, adhesive grades for PPy-T and PPy-I coatings on copper surface ( Figure 3 d) can be classified as 2B and 4B, respectively.…”

“…Notably, the constant phase element ( Q ), rather than the pure capacitance, was utilized to compensate the dispersion effect caused by the surface inhomogeneity of solid electrode. The impedance of Q ( Z Q ) can be expressed according to the equation [ 31 ]: where Y 0 is the proportional factor, j is the imaginary root ( j 2 = −1), ω is the angular frequency (2 π f ) and n is the phase shift exponent that determined by the degree of surface heterogeneity. Considering the actual circumstance of measured specimens, the film capacitance ( C f ) and double-layer capacitance ( C dl ) were derived through the following equations [ 17 ]: where ω ′ denotes the angular frequency when the imaginary frequency reaches the maximum, Y dl is a constant for Q dl ; R s and R f are solution and charge transfer resistances, respectively.…”

“…Consequently, higher C f values are obtained for coated samples. Moreover, Shahryari and co-workers [ 31 ] articulated that C f was also tightly related to the thickness of conductive coatings; the larger the C f value is, the higher the thickness of the coating. This conclusion is strongly supported by our microscopic observations in Figure 3 a,b, in which the PPy-I coating exhibits higher thickness than that of PPy-T. Additionally, of note in Table 3 , C dl varies in a similar manner to C f , presenting the highest value (145.20 μF/cm 2 ) for the PPy-I-coated specimen.…”

“…The exposed substrate and residual PPy coating can be distinguished in Figure 6 a, in which the embedded salt grains are also differentiated owing to the block of incomplete coating architecture. Another aspect, the reduction (herein, de-doping of C 2 O 4 −2 ) and ultimate degradation of the conductive coating in aggressive media also contributed to the delamination of the protective layer [ 31 ]. It is precisely for the degraded coating surface that the CA value (inset of Figure 6 a) emerges as an extremely hydrophilic feature (15.9°).…”

Superior Long-Term Corrosion Inhibition of N80 Steel by New Eco-friendly Hydrazone-Based Compounds in a Simulated Oil Well Acidizing Environment: Establishing the Mechanism at the Molecular Level

“…Besides, it can be observed that the C eff’dl values significantly decreased after the addition of increasing dosage of inhibitors. It has been stated that “ the significant decrease in the capacitance values can be attributed to an increase in the thickness of the double electric layer due to the inhibitor’s adsorption on the metal surface ”. , In this situation, the adsorption of inhibitor molecules leads to the modification of the double layer behavior due to the inhibitor film formed on the steel surface. , That is said, the strength of adsorption is associated with inhibitors’ molecular structures and the stable adsorption geometry over the steel surface. Deep insights about this will be given in theoretical sections.…”