Synthesis Of Nitrogen And Sulfur-doped Carbon Dots And Its Corrosion Inhibition Behavior For Q235 Steel

Carbon steel is widely used in construction,piping,transportation,and marine owing to its low cost,high flexibility,and good weldability.However,carbon steel is prone to corrosion in environmental medium,which causes huge economic losses and threatens personal health.Therefore,measures such as coatings,electrochemical protection methods or corrosion inhibitors are usually used to prevent metal corrosion.Corrosion inhibitors are often used in pickling processes such as oil wells and natural gas pipelines to deal with dirt,deposits,or rust due to their low dosage,good effect,and simple operation.In recent years,the main research direction of corrosion inhibitors had been the development of efficient and environmentally friendly corrosion inhibitors.Therefore,carbon quantum dots with multiple active sites and good biocompatibility have gradually become hot dots in corrosion inhibitor research.Based on this,nitrogen-doped carbon dots and nitrogen/sulfur co-doped carbon dots were prepared by the hydrothermal method.Their structure,morphology,and corrosion inhibition mechanism were systematically explored.The main research results are as follows:(1)Synthesis of nitrogen-doped carbon quantum dots(EDAN-CDs)using aliphatic citric acid and ethylenediamine as precursors are graphene-like structures with abundant active functional groups and good water solubility.The electrochemical test results showed that the corrosion inhibition efficiency of EDAN-CDs on Q235 steel reach 93%.It is attributed to the multiple active centers in EDAN-CDs and the metal atoms in Q235 steel through chemical bonding and electrostatic adsorption on the surface to form dense adsorption film,thereby inhibiting the electron transfer during the corrosion reaction,and effectively slowing down the corrosion of Q235 steel.(2)Nitrogen-doped carbon dots(OPDN-CDs)were synthesized from polyphenyl folic acid and o-phenylenediamine precursors.It is an amorphous carbon-based nanomaterial composed of abundant amino,phenyl,and carboxyl active functional groups on the surface.The unique microstructure and active functional groups make the corrosion inhibition performance of OPDN-CDs better than that of EDAN-CDs,with a corrosion inhibition efficiency of 96%.(3)Nitrogen/sulfur co-doped carbon dots(N,S-CDs)were synthesized using ophenylenediamine and thiourea as precursors.Electrochemical tests demonstrated that the corrosion inhibition efficiency of the prepared N,S-CDs is as high as 98%,which is better than the corrosion inhibition performance of N-CDs.The thickness of the adsorption film on the surface hinders the transfer of electrons and reduces the corrosion current density,effectively delaying the corrosion of Q235 steel.