Electrochemical evaluation of nanostructured coatings for corrosion protection of structural metals

Corrosion of steel and other construction metals represents a critical threat to infrastructure durability, and recent advances in nanotechnology have inspired a new generation of protective coatings with superior performance. This review provides a comprehensive analysis of electrochemical methods used to evaluate nanocoatings (nanostructured coatings and nano-additive-modified coatings) and highlights how different classes of nanoscale materials improve corrosion resistance. Techniques such as potentiodynamic polarization, electrochemical impedance spectroscopy, linear polarization resistance, and localized probes not only quantify reductions in corrosion current and increases in charge-transfer resistance, but also clarify the mechanisms by which nanostructured additives function. Inorganic nanoparticles such as silica, titania, and ceria enhance barrier density and adhesion, while layered clays and double hydroxides impart both tortuous diffusion paths and inhibitor release capability. Carbon-based nanomaterials, including graphene, graphene oxide, and carbon nanotubes, offer unique two-dimensional or fibrous architectures that create highly effective barriers, though their long-term behavior depends strongly on dispersion, orientation, and defect control. Conductive polymers and hybrid composites integrate active passivation with structural reinforcement, and self-healing nanocontainer systems demonstrate the ability to autonomously restore protection at damaged sites. By comparing diverse strategies, this review emphasizes the interplay between barrier effects, active inhibition, and mechanical reinforcement, while also recognizing the challenges of durability, scalability, and environmental safety. Overall, electrochemical insights have advanced both the understanding and optimization of nanocoatings, guiding the design of multifunctional systems that can extend service life and reduce maintenance costs for critical infrastructure.