Improved corrosion resistance of AZ31 Mg alloy coated with MXenes/MgAl-LDHs composite layer modified with yttrium

MXenes, a novel two-dimensional (2D) material of Ti3C2, present wide applications in energy-related fields. However, a mass of sedimentary multilayer Ti3C2 was discarded and non-recyclable due to incomplete exfoliation in the preparation of single layer Ti3C2. In this work, a composite structure, mixing MXenes/magnesium aluminum-layered double hydroxides (MXenes/MgAl-LDHs) with Y(OH)3, was synthesized in-situ as a smart coating on Mg alloy AZ31 via (i) exfoliating those multilayer Ti3C2 to few-layer MXenes (FLMs), and (ii) adding Y(NO3)3 to FLMs solution for a one-step hydrothermal treatment. Results show the electronegative mainboard of MXenes can effectively absorb cations in the reaction solution, and promote growth of MgAl-LDHs and Y(OH)3 on its surface. Moreover, MgAl-LDHs being the intermediate connector facilitate growth of MXenes upon the surface of Mg alloy AZ31. The corrosion tests indicated that the composite coating modified with yttrium had an excellent anticorrosion performance (Ecorr = −0.36 VSCE, Icorr = 9.12 × 10−9 A cm−2) and self-healing ability. Further, the formation and corrosion mechanism of composite coatings were finally proposed.