Adsorption behavior and inhibition performance of 2-amino-5-bromothiazole on steel surface in HCl solution

• 2-Amino-5-bromothiazole (2-ABT) exceeds 90.0% inhibition for steel in 1.0 M HCl. • Adsorption of 2-ABT on steel surface follows the Langmuir isotherm with strong chemisorption. • 2-ABT acts as a mixed-type inhibitor by inhibiting both anodic and cathodic reactions. • Lone electron pairs on S and N atoms of 2-ABT promote strong adsorption on the metal surface. • The planar benzene ring enhances adsorption stability through π-electron interaction with the metal surface. Thiazole compounds possess strong adsorption properties and modifiable molecular structures, offering great prospects for their application in developing a new generation of highly efficient inhibitors. 2-amino-5-bromothiazole (2-ABT) establishes strong interfacial interactions with cold-rolled steel (CRS) in acidic media through the cooperative contribution of N and S heteroatoms. These interactions promote the spontaneous formation of a compact and continuous adsorbed layer at the surface, thereby effectively alleviating acid-induced corrosion. At low inhibitor concentrations, the interfacial film limits the transport and interfacial reactions of corrosive species, leading to the inhibition of anodic dissolution and cathodic hydrogen reaction. The improvement in surface wettability further enhances the stability and barrier capability of the adsorbed layer. N and S atoms are identified as the primary adsorption centers, with inhibitor molecules adopting a nearly parallel adsorption on the Fe (110) surface. The integrated experimental and theoretical insights demonstrate that the synergy between adsorption configuration and molecular active sites represents the essential physicochemical basis for effective corrosion protection.