Multifaceted insights of experimental, surface, and computational investigations for a synthesized pyrazolyl derivative inhibitor for carbon steel corrosion in an acidic environment

For sustainable corrosion protection, this study introduces newly synthesized pyrazolyl- N -acetylthiocarbohydrazone ( PTH ) as a highly efficient and environmentally friendly inhibitor for carbon steel (CS) in an aggressive 1.0 M HCl solution. A comprehensive evaluation of PTH inhibition performance was conducted through chemical weight loss and electrochemical techniques, involving potentiodynamic polarization ( PDP ) and electrochemical impedance spectroscopy ( EIS ), which demonstrated a significant reduction in CS corrosion. PDP and EIS reinforced these findings, confirming the robust protective nature of PTH with an inhibition potency of 96%. The mitigation power of the PTH can be explained by its adsorption onto the CS surface, which followed the Langmuir adsorption model. The inhibitor exhibited exceptional stability and efficiency across varying temperature conditions and various immersion times using EIS, reinforcing its reliability in harsh acidic media, with a mitigation capacity of 97.16% at 50 °C and 97.3% after 24 h. The morphology of the CS surface was examined using SEM /EDX (Scanning Electron Microscopy), AFM (Atomic Force Microscopy), and XPS (X-ray Photoelectron Spectroscopy), exhibiting the PTH adsorption over CS , which was also proved and elucidated employing theoretical quantum investigations as density functional theory and Monte Carlo simulations.