Triphenylphosphine-functionalized graphene oxide: A novel corrosion inhibitor for carbon steel in acidic environments

In this work, triphenylphosphine (TPP) was reacted with graphene oxide (GO) to obtain the modified nanomaterial TPP-functionalized graphene oxide (GP). Both GO and GP were characterized using fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The calculated crystallite sizes of GO and GP are 16 nm and 6.10 nm, respectively, based on XRD patterns using both the Debye–Scherrer and Williamson–Hall equations. The microstrain of the GP compound was found to be -0.57385. FESEM analysis revealed that GO consists of thin sheets, while the surface morphology of GP exhibited crumpled and rippled, sharp-edged structures. The efficiency of the synthesized GP compound as a corrosion inhibitor for carbon steel in acidic media (HCl) was evaluated at varying concentrations (1–6 ppm) and temperatures (298, 308, 318, and 328 K). The behavior of the inhibitor GP was studied by using the Tafel polarization method to determine the inhibition efficiency. Furthermore, kinetic parameters, including activation of change in enthalpy (∆H*), activation of change in entropy (∆S*), activation energy (Ea), and activation of change in Gibbs free energy (∆G*), were calculated to understand the corrosion inhibition and adsorption mechanism for the synthesized nano-organic compound in addition to the thermodynamic functions of adsorption such as ΔG_{ads}^° , ΔH_{ads}^° and ΔS_{ads}^° . The studied inhibitor reveals a mixed inhibition behavior by chemisorption mode with a maximum inhibition efficiency of 96.40% at 6 ppm and 328K.