Electrostatic self-assembled MXene@PDDA-Fe3O4 nanocomposite: A novel, efficient, and stable low-temperature phosphating accelerator

[Display omitted] •1) The application of the binary nanocomposite in phosphating treatment was explored for the first time.•2) MXene@PDDA-Fe3O4 had excellent dispersion stability in the phosphating bath.•3) The MXene@PDDA-Fe3O4 nanohybrid is a efficient nanoaccelerator.•4) The promotion mechanism of accelerators on phosphating treatment was discussed. In this study, MXene@PDDA-Fe3O4 binary hybrid (MPF) was synthesized by electrostatic self-assembly and incorporated into the low-temperature phosphating as an accelerator. MXene@PDDA-Fe3O4 with a large specific surface area exhibited excellent dispersion stability, structural stability, and the ability to selectively attract metal ions in the phosphating bath, which was conducive to the formation of the dense phosphating coating. The phosphate coating obtained from a phosphating bath containing 0.12 g/L MXene@PDDA-Fe3O4 (12-MPF coating) had the lowest porosity among all samples, which was decreased by 99.07% in comparison to the blank coating. Moreover, the EIS test revealed that 12-MPF coating exhibited the highest low-frequency impedance among all samples, which is more than an order of magnitude higher than that of blank coating, indicating that 12-MPF coating has excellent corrosion resistance. This notable improvement can be attributed to several factors, including the large specific surface area of MXene, the synergistic inhibitory effect of poly (dimethyl diallyl ammonium chloride) (PDDA) and Fe3O4 on agglomeration tendency of MXene, as well as the selective adsorption of Fe3O4 on metal ions. This study demonstrates the significant potential of the 0D/2D binary hybrid in phosphating treatment.