The use of Piper Betle leaf extract for forming a barrier layer on steel surface in hydrochloric acid solution

•PBLE is an effective inhibitor for steel corrosion in hydrochloric acid solution.•Corrosion resistance is probably improved via the formation of a nano porous film.•A robustly protective film formation could hinder the electrochemical corrosion.•A denser nano porous film was obtained when increasing PBLE’s concentration. Leaf extracts are widely used to mitigate the steel corrosion in an acidic environment. This work focuses on the effective acidic inhibition of a Piper Betle leaf extract (PBLE) that can be added to a green corrosion inhibitor system, giving a high corrosion inhibition performance of steel in a 0.1 M HCl solution. The relatively destructive potentiodynamic (PD) and potentiostatic (PS) polarizations combined with some non-destructive electrochemical techniques, including linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS), perform the high corrosion inhibition likely a mixed behavior for steel in investigated solution. Surface analysis demonstrates that the nano porous film formation is PBLE concentration dependent. The results indicate that the inhibition efficiency is increased by the addition of PBLE at a concentration up to 2000 ppm due to a compact, robust, and uniform protective film formation. Moreover, an increase in PBLE concentration up to 2500 ppm decreased the inhibition efficiency due to a decrease of the PBLE species’ activity in the solution that significantly affects the nano porous film formation. This work suggests a new inhibitor that can be added to a green corrosion inhibitor system for delivering high corrosion resistance of steel through a controlled surface treatment.