Distinctive roles of graphene oxide, ZnO quantum dots, and their nanohybrids in anti-corrosion and anti-fouling performance of waterborne epoxy coatings

• Hybrids of graphene oxide and ZnO quantum dots (GO@ZnO QDs) are synthesized. • Waterborne epoxy coatings loaded with silane grafted GO@ZnO QDs are prepared. • Nanocomposite coatings show advanced corrosion resistance in NaCl solution. • Nanocomposite coatings show both anti-fouling and anti-bacterial properties. • Nanocomposite coatings have high adhesion strength and water contact angle. In this research, the amino-silane functionalized ZnO quantum dots (F-ZnO QDs), graphene oxide (F-GO), and their nanohybrids (F-GO@ZnO QDs) are used as effective nanofillers to improve the anti-corrosion and anti-fouling properties of waterborne epoxy coatings. The synthesized nanomaterials before and after silane functionalization are characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Then, the nanocomposite waterborne epoxy coatings loaded with 0.1 wt% F-ZnO QDs, F-GO, and F-GO@ZnO QDs are prepared through solution mixing method. The effects of different nanofillers on the surface roughness, water contact angle, pull-off adhesion strength, fracture surface, and corrosion resistance of the nanocomposite coatings are considered. The results reveal that the uniformly dispersed F-GO@ZnO QDs in the fracture surface of the coating could provide the highest barrier and corrosion resistance on the steel substrates. Meanwhile, the nanocomposite coatings have higher water contact angle and higher adhesion strength to the substrates. The anti-bacterial and anti-fouling properties of the nanocomposite coatings have also been confirmed. The multifunctional performance of the epoxy/F-GO@ZnO QDs is assigned to the synergy effect between the GO, ZnO QDs, and amino-silane; exhibiting the importance of the nanohybrids to combine the advantages of different nanomaterials in one coating system.