Avaliação de carbon dots como inibidor de corrosão – efeito do elemento de dopagem

Abstract

Carbon-based nanomaterials have attracted increasing interest in the development of new technologies across various research fields. Among them, Carbon Dots (CDs) stand out as nanoparticles exhibiting attractive properties such as high aqueous solubility, large surface-to-volume ratio, low toxicity, and ease of functionalization. Such characteristics favor the use of these nanomaterials as potential corrosion inhibitors, one of the most relevant corrosion mitigation strategies in recent years, which has shown a growing demand for new molecules that are both effective and environmentally friendly. In this work, CDs were synthesized via a bottom-up hydrothermal route with variation in

chemical precursors to obtain different elemental compositions: undoped CDs, nitrogen- doped CDs (N-CDS), and nitrogen and sulfur co-doped CDs (NS-CDS). The objective

was to evaluate the effectiveness of these particles as corrosion inhibitors for carbon steel in a saline medium saturated with carbon dioxide (CO2), as well as to investigate the effects of operational variables such as temperature and pressure. The physicochemical characterization of the particles was performed by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible absorption spectroscopy (UV-Vis), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The evaluation of anticorrosion performance was conducted using electrochemical techniques such as linear potentiodynamic voltammetry (LPV), electrochemical impedance spectroscopy (EIS), gravimetric tests, and morphological analyses by optical microscopy (OM), scanning electron microscopy (SEM), AFM, and Raman spectroscopy. The results demonstrated that the presence of heteroatoms significantly enhanced the particles’ performance, with NS-CDS showing the highest efficiency, reaching values above 95% under severe test conditions, including 60 °C temperature and 10 bar pressure. Electrochemical data indicated a marked increase in charge transfer resistance, while surface tests revealed the formation of a continuous and adherent protective layer consistent with a chemical adsorption mechanism. The superior performance of NS-CDS particles highlights their potential as efficient, versatile, and environmentally friendly corrosion inhibitors with promising applicability in aggressive industrial environments.