Nitrogen-doped carbon dots as high-effective inhibitors for carbon steel in acidic medium

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2021-05, Vol.616, p.126280, Article 126280
• Main Authors: Cao, Shuyun, Liu, Dan, Wang, Tianxiang, Ma, Aijing, Liu, Chengwei, Zhuang, Xupin, Ding, Hui, Mamba, Bhekie B., Gui, Jianzhou
• Format: Article
• Language: English
• Subjects: Acid corrosion; Adsorption; Carbon dots; Carbon steel; Inhibitor
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2021.126280

Eco-friendly carbon dots (CDs), with N-doped functionalized groups, were found to be an effective corrosion inhibitor for carbon steel in 0.5 M H2SO4 medium. Their corrosion inhibition behavior was systematically investigated by electrochemical method and micromorphology analysis. The results showed that the N-CDs could suppress the anodic and cathodic reaction by adsorption to form a barrier onto the steel surface, preventing the transportation of corrosive particles in the bulk solution, which follows the Langmuir adsorption isotherm. It can further increase the inhibition efficiency by increasing the N-CDs amount. The inhibition mechanism was also proposed, which could provide a guide to search for new nanomaterials for metal against corrosion. [Display omitted] •N-doped functionalized carbon dots (N-CDs) can act as effective inhibitors, suppressing both anodic and cathodic reaction.•N-CDs adsorb onto the steel surface by forming a barrier against corrosive species, following the Langmuir adsorption model.•Pyridine-N and pyrrole-like N are responsible for chemisorption. While graphitic N form a shield via physical adsorption. Carbon dots (CDs), a new class of nanomaterials, are found to be good inhibitors. Given that there is no clear mechanistic explanation in the literature on how the CDs inhibit the corrosion of carbon steel in H2SO4 medium. Eco-friendly nitrogen-doped functionalized carbon dots (N-CDs) were facilely synthesized via the one-step hydrothermal reaction of two low-cost raw materials with multiple functional groups, i.e., citric acid and urea. Their corrosion inhibition behavior was systematically investigated via electrochemical methods and surface analysis. The resultant N-CDs were found to be an effective corrosion inhibitor for carbon steel in 0.5 M H2SO4 solution at 30 mg/L, with the inhibition efficiency exceeding 95 % at 298 K. The N-CDs can be adsorbed onto the steel surface by forming a barrier to prevent/ reduce the attack of corrosive ions, which follows the Langmuir adsorption model. Their inhibition mechanism was also proposed, providing a guide to search for new nanomaterials for metal against corrosion.