Melamine modified carbon dots as high effective corrosion inhibitor for Q235 carbon steel in neutral 3.5 wt% NaCl solution

Melamine modified carbon dots (Me-CDs) was synthesized by hydrothermal method and used as effective corrosion inhibitor for Q235 carbon steel in 3.5 wt% sodium chloride (NaCl) solution. The microstructure and surface properties of Me-CDs were characterized using XRD, FTIR, XPS and TEM. The corrosion inhibition behavior and mechanism of Me-CDs for carbon steel were investigated using weight loss and electrochemical methods, in combination with some surface characterizations (including SEM, AFM and contact angle tester). Results showed that Me-CDs as mixed-type adsorbent inhibitor could effectively prevent carbon steel from corrosion, and the maximum corrosion inhibition efficiency can reach 92.36% at 200 mg/L. The absorption of Me-CDs conformed to Temkin adsorption model, involving both chemisorption and physisorption. Based on the results of characterization analysis, the chemisorption from multiple adsorption centers, physisorption by blocking and barrier effect, and the formation of hydrophobic film on the surface of carbon steel was proposed to clarify the corrosion inhibition mechanism of Me-CDs.