Synthesis, Characterization, and Corrosion Inhibition Performance of 5-Aminopyrazole Carbonitriles Towards Mild Steel Acidic Corrosion

The present study deals with the corrosion inhibition performance of three 5-aminopyrazole carbonitriles (designated as AHPC, ANPC, and AMPC) on mild steel in 1M HCl medium using gravimetric, electrochemical, surface, and density functional theory (DFT) methods. Gravimetric measurements revealed that inhibition efficiency of the tested compounds increases on increasing their concentration and that AHPC, ANPC, and AMPC showed the highest efficiencies of 90.34%, 92.04%, and 95.45%, respectively, at 7.69 × 10⁻⁴ M concentration. Electrochemical studies suggest that tested inhibitor molecules act as mixed type corrosion inhibitors and also enhance charge transfer resistance for corrosion process. Surface morphological studies carried out using SEM and AFM studies revealed that AHPC, ANPC, and AMPC molecules adsorb and form surface protective film. DFT study revealed that AHPC, ANPC, and AMPC molecules showed strong interactions with the metallic surface and adsorb strongly.