Experimental and theoretical insights on long-term corrosion protection performance of MXene Nanosheets decorated with graphene quantum dots in epoxy coatings

Abstract

In this study, MXene nanosheets decorated with zero-dimensional graphene quantum dots and functionalized with 3-aminopropyltriethoxysilane (APTES-MXene@GQDs) are used as a nanofiller in epoxy coatings. The MXene@GQDs and APTES-MXene@GQDs are characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results prove that the GQDs with spherical size (≤ 10 nm) have covered the MXene nanosheets through creating C-O-Ti covalent bonds. The Si-O-C and Ti-O-Si bonds in the APTES-MXene@GQDs indicate that both MXene and GQDs have reacted with the APTES molecules. The results of electrochemical impedance spectroscopy reveal that the low-frequency impedance modulus of epoxy coatings loaded with 0.1 wt% APTES-MXene@GQDs is 4.4 × 109 and 6.4 × 108 Ω.cm2 after 1 day and 7 weeks of immersion in NaCl solution, respectively. Meanwhile, hydrophobic coatings with high adhesion strength are achieved by adding the modified nanofillers. Density Functional Theory calculations emphasize the potential of MXene@GQDs nanohybrids in corrosion protection. The COO covalent bond significantly bolsters stability, making it a strong contender. An efficient electron transfer, as revealed in charge transfer dynamics, reinforces the interactions. The presence of MXene reshapes the electronic landscape, facilitating robust charge transfer processes. Conversely, the systems lacking MXene exhibit less advantageous energy level placement.