Bio-inspired Ti3C2Tx MXene composite coating for enhancing corrosion resistance of aluminum alloy in acidic environments

Aluminum alloy (Al alloy) suffers from severe corrosion in acidic solution. Two-dimensional (2D) MXene-based composite coatings show great prospects for corrosion protection on metals used in special conditions. The composite coatings still face challenges in complex functionalization and orientation control. In harsh conditions, the long-term ability and roles of MXene in corrosion protection are still not clear. Here, a bio-inspired myristic-calcium chloride-Ti3C2Tx MXene (MA + CaCl2 + MXene) composite coating is successfully prepared on aluminum alloy (Al alloy) by electrodeposition process. Electrochemical tests, surface morphology, and chemical composition are analyzed to investigate the corrosion resistance and protection mechanism of the MXene coating in acidic solution (0.5 M H2SO4 + 2 ppm HF). As a result, the incorporation of MXene can significantly reduce corrosion current density (7.498 × 10-8 A/cm2) by ∼ 5 orders of magnitude and impedance modulus at 0.01 Hz (|Z|0.01 Hz) value of the composite coating is 196.8 Ω·cm2, which is over 4 times higher than that of bare Al alloy (40.74 Ω·cm2) after immersion test for 72 h. Furthermore, the in-situ corrosion test confirms the enhanced corrosion resistance of the MA + CaCl2 + MXene composite coating. The MXene can increase coating thickness to 23.6 ± 0.4 μm, reduce porosity to (5.845 ± 1) × 10-5, decrease the diffusion coefficients of H+ to (1.587 ± 0.3) × 10-9 cm2/s, and enhance the adhesion of the coating to the substrate (the delamination time exceeds 5 h), thus providing improved anti-corrosion ability. This strategy opens up new prospects for construction of 2D MXene-based anti-corrosion coatings.