Amelioration of 2D hybrid architecture for protective surface using thiourea-based inhibitor: Electrochemical and computational perspectives

Abstract

The coexistence of inorganic and organic substances is desirable for protecting metallic materials from corrosive environments. Nonetheless, the interaction and in situ formation mechanism of 2D hybrid architectures have not been reported. For this purpose, three distinctive thiourea-based (TB) compounds (namely, thiourea (TU), 1-phenylthiourea (PTU), and 1,3-diphenyl-2-thiourea (DPTU)) were used as organic inhibitors to understand how the chemical structure of the inhibitors affected their interaction with the porous inorganic layer. The TB compounds were used to control the corrosion kinetics by adding inhibitors into corrosive environments that interact readily with the pre-existing inorganic layer fabricated by plasma electrolysis oxidation (PEO). This resulted in a hybrid layer because the TB compounds were actively adsorbed onto the inorganic layer, thereby sealing the defects effectively. The heteroatom adjacent to the thiourea sites were the primary sites for bonding with the inorganic layer. Moreover, the presence of a benzene ring considerably increased the feasible adsorption patterns. The increment in chemical reactivity during adsorption permitted more interaction with the Cl− ions from a corrosive environment to form a 2D hybrid layer through complex coordination. This layer showed an improvement in corrosion performance. Furthermore, the computational perspectives effectively explained the adsorption and interfacial reaction of the 2D hybrid layer with the inorganic layer and reinforce the correlation with the experimental observations.