Corrosion Inhibition Effect of 2‐([(1E)‐(2‐hydroxyphenyl)methylene]amino) Benzoic Acid on Nickel in Sulfuric Acid: Electrochemical, Charge‐Discharge and Computational Studies

Abstract Ni‐based alloys have excellent corrosion resistance and are widely used in the petrochemical industry. In this study, the effect of sulfuric acid on the corrosion resistance of Ni was analyzed by electrochemical tests and theoretical studies in the absence and presence of 2‐([(1E)‐(2‐hydroxyphenyl)methylene]amino)benzoic acid (H2 L). Sulfuric acid's corrosive effect, notably in fertilizer production, poses challenges for materials like nickel used in storage and transport. Discussion of nickel corrosion which is frequently used to handle sulfuric acid is given in this paper. The corrosion behavior of nickel (Ni) metal and the inhibitory effect of 2‐([(1E)‐(2‐hydroxyphenyl)methylene]amino)benzoic acid (H 2 L) were investigated using a combination of electrochemical and computational approaches. In this study, 0.5 M sulfuric acid served as the corrosive medium. The inhibitory effect of H 2 L was evaluated using Tafel plots and electrochemical impedance spectroscopy. Results show a gradual decrease in the corrosion current density ( I corr. ) over time, accompanied by an increase in inhibition efficiency, attributed to rising additive concentrations. The maximum inhibition efficiency ( η =97.8 %) was achieved at 1×10 −5 M additive concentration and 25 °C. The additive predominantly affects the anodic reaction compared to the cathodic reaction and reduces NiO formation on electrode surfaces. Increasing solution temperature enhances inhibition efficiency, indicating chemisorption following the Langmuir model, supported by electrochemical impedance spectroscopy. Scanning electron microscopy (SEM) analysis confirms that H2 L inclusion significantly enhances nickel corrosion resistance. Charge‐discharge processes of Ni were studied in 0.5 M H 2 SO 4 containing various dosages of the additive at applied distinct current densities. It is interesting to note that both discharging time and specific capacitance rises with raising the applied current density at each dosage of additive in 0.5 M H 2 SO 4 . The most enhancements were obtained at presence of 1×10 −5 M of the additive, as corrosion resistance and specific capacitance (0.391 mAh at 90 mA cm −2 ). Also, improved power and energy features are obtained in the presence of this concentration of the additive. Theoretical Density Functional Theory (DFT) studies reveal that H 2 L possesses a low ΔE gap , facilitating chemical adsorption during the inhibition process, underlining the innovative nature of this corrosion inhibition strategy. Furthermore, the H 2 L−Ni interaction was effectively simulated using the DFT/B3LYP/6‐311+G**, providing valuable insights into the compound's corrosion inhibition capabilities.