Recent advancements in corrosion inhibitor systems through carbon allotropes: Past, present, and future

Nano-sized carbon allotropes, particularly graphene (G), graphene oxide (GO), single and multi-walled carbon nanotubes (CNTs, SWCNTs, and MWCNTs) and their chemically modified derivatives are widely used in anticorrosive coating formulations. Generally, carbon allotropes acquire nanofiller property and high hydrophobicity which make them ideal anticorrosive materials. Along with various advantages, using carbon allotropes as anticorrosive materials are connected with some specific challenges including un-controlled dispersion in polymer matrixes. Chemical functionalization using covalent and non-covalent methods are widely used to enhance their dispersibility. Magnetic stirring, ultrasonic mixing, ball milling and shear emulsification are also widely used to enhance their dispersibility. Present review article describes the covalent and non-covalent functionalization of G, GO, and CNTs and their application as corrosion inhibitors in various coating formulations and aqueous phase. Chemically modified GO shows remarkable solubility/dispersibility in the aqueous electrolytes. Advantages and challenges using these materials as corrosion inhibitors have also been discussed herein