Natural chitosan-based carbon dots as an eco-friendly and effective corrosion inhibitor for mild steel in HCl solution

l-Tyrosine-Derived Nitrogen-Doped Carbon Dots Synthesized via a Hydrothermal Approach for Corrosion Mitigation of Mild Steel in 15% Hydrochloric Acid Solution

l-Tyrosine-based eco-friendly nitrogen-doped carbon dots have been synthesized using citric acid and isoniazid as precursors along with l-tyrosine via a facile one-pot hydrothermal approach for the corrosion mitigation of mild steel (MS) in HCl solution (15%). The authenticity of the synthesized carbon dots has been established using various spectroscopic techniques such as X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), and Fourier transform infrared (FT-IR) spectroscopy. The inhibition behavior was studied using gravimetric analysis, electrochemical measurements, and surface analysis. The potentiodynamic polarization revealed that the N-doped carbon dots act as a mixed-type corrosion inhibitor; that is, it can act as both a cathodic as well as an anodic inhibitor, with the corrosion efficiency of 99.3% at the concentration of 150 ppm. N-CDs protect the metal surface by forming a layer that is particularly physisorbed as confirmed by ΔGabs values.

In-Depth Insight into Corrosion Inhibition Performance of Sweet Potato Leaf Extract as a Green and Efficient Inhibitor for 6N01 Al Alloy in the Seawater: Experimental and Theoretical Perspectives

Corrosion protection of metal has become an important and urgent topic, which requires the development of an inexpensive, environmentally friendly, and highly efficient corrosion inhibitor. Herein, a sweet potato leaf extract (SPL) was obtained by a simple water-based extraction method and then as a green corrosion inhibitor for 6N01 Al alloy in the seawater was well investigated by the weight loss method and various electrochemical tests. Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-vis) spectroscopies were carried out to investigate the compositions of SPL. The findings from the potentiodynamic polarization (PDP) curves suggest that SPL functions as a typical mixed-type corrosion inhibitor. Notably, the maximum corrosion inhibition efficiency reaches 94.6% following a 36 h immersion period at 25 °C. The adsorption behavior of SPL on the Al alloy surface belongs to the Langmuir adsorption isotherm. The Gibbs free energy value illustrates that the adsorption of SPL contains both physisorption and chemisorption. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) indicate that SPL is firmly attached to the Al alloy surface by making a protective layer, which can effectively inhibit the corrosion of the Al alloy in the seawater. Furthermore, quantum chemical calculations were applied to validate the chemical adsorption and elucidate the relationship between the electronic structure of the active components in SPL and their effectiveness in corrosion inhibition.