Environmentally friendly expanded graphite-doped ZnO superhydrophobic coating with good corrosion resistance in marine environment

Abstract Designing and fabricating the marine anti-corrosion materials without fluorine by superhydrophobic method is a huge challenge. In this study, an environmentally friendly composite coating was prepared by combing modified expanded graphite (EAG) with nano zinc oxide (ZnO). This coating showed superhydrophobic surface and good corrosion resistance. Fourier transform infrared spectroscopy (FITR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to characterize the materials in fabricating process of the coating. The properties of three composite coatings (ZnO, EAG, and EAG@ZnO) were analyzed, including surface roughness, water contact angle, corrosion resistance, self-cleaning and anti-fouling. The combination of ZnO and EAG caused a big water contact angle, leading superhydrophobic surface of the composite coatings. The electrochemical results showed that the superhydrophobic EAG@ZnO coating had a larger capacitive arc diameter and charge transfer resistance, indicating the enhanced anti-corrosion resistance. Meanwhile, the EAG@ZnO coating also showed good self-cleaning and anti-fouling performance according to solid and liquid pollutants tests. In addition, the mechanical properties and stability of the superhydrophobic EAG@ZnO coatings were evaluated by knife peeling and finger scratch tests. In summary, these superhydrophobic and anti-fouling EAG@ZnO composite coatings provide a potential application in marine corrosion and protection field. Graphical Abstract