Magnetite-facilitated growth of a layered double hydroxide film on steel for improved anti-corrosion

Layered double hydroxide (LDH) grown in situ on steel is an effective protective anti-corrosion coating. However, improving the anti-corrosion performance of LDH films through microstructure regulation is challenging owing to the limited understanding of the in situ growth mechanism. In this study, density functional theory (DFT) calculations revealed that Al(OH)3 could strongly adsorb to the (004) lattice plane of Fe3O4. Therefore, Fe3O4 was introduced on the steel surface through pretreatment with nitric acid. A dense and tightly bonded MgAl-CO32- -LDH film was successfully grown in situ on the surface of the Fe3O4-modified steel, and the film exhibited a high corrosion protection efficiency of 99.5%. The Fe3O4 played a vital role in the growth process of the MgAl-LDH film. The Al(OH)3 and Al-rich LDH with vacant sites provided dense nucleation sites for the growth of MgAl-LDH, which was the key to the formation of an effective film. This work elucidates the in situ growth mechanism of the LDH film on steel and provides an alternative method for improving the anti-corrosion performance of LDH films.