Next-Generation Smart Nanocomposite Coatings for Metallic Corrosion Protection: From Passive Barriers to Active and Self-Healing Systems

A lot of attention has been paid to the development of advanced corrosion-resistant coatings because of the growing need to protect metals in a way that is long-lasting, useful in many situations, and good for the environment. Conventional protective coatings mostly use passive barrier mechanisms, but their long-term effectiveness is often limited by electrolyte penetration, mechanical damage, interfacial degradation, and aging in the environment. Recently, progress in nanotechnology has made it possible to create smart nanocomposite coatings that have the ability to improve passive barriers, stop active corrosion, respond to stimuli, and heal themselves. This review takes a close look at how polymeric, ceramic, and organic–inorganic hybrid coatings have changed over time. It looks at how functional nanomaterials like graphene and graphene oxide, MXenes, hexagonal boron nitride, metal oxide nanoparticles, layered double hydroxides, and metal–organic frameworks have been added. The correlation between properties of nanofillers, their dispersion, interfacial interaction, coating structure and principles of stopping the corrosion is discussed in detail.