Exploring the adsorption and corrosion inhibition properties of indazole as a corrosion inhibitor for brass alloy in HCl medium: A theoretical and experimental study

This study aims to evaluate the inhibition performance of new indazole-derived compounds, namely 3,3-dimethyl-13- (4-nitrophenyl)- 3,4-dihydro-1H- indazolo [1,2b] phthalazine 1,6,11 (2H,13H) trione (Ind-NO2) and 3,3-dimethyl-13-(p-tolyl)-3,4-dihydro-1H-indazolo[1,2-b]phthalazine-1,6,11 (2H,13H)-trione (Ind-CH3), in preventing the corrosion of brass in a highly corrosive medium containing 1.0 M hydrochloric acid (HCl). The inhibitory performance was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods. A considerable decrease in the corrosion rate of brass was observed when treated with these compounds compared to the uninhibited solutions. The EIS analysis suggested the formation of a protective coating on the brass surface by the inhibitors, leading to an enhanced barrier to electron transfer and reduced corrosion rate.The formation of this protective coating was further confirmed through SEM-EDX analysis and X-ray photoelectron spectroscopy. The chemical reactions occurring during the corrosion and inhibition processes were identified using ICP-OES and UV–vis spectroscopy. Additionally, DFT calculations of Ind-NO2 and Ind-CH3provided molecular-level insights into the inhibition mechanism. These findings contribute to the development of anti-corrosion materials and indicate the potential application of these compounds in real-world settings.