Growth of NiAl-Layered Double Hydroxide on Graphene toward Excellent Anticorrosive Microwave Absorption Application

High-performance microwave absorbers with special features are desired to meet the requirements of more complex modern service environments, especially corrosive environments. Therefore, high-efficiency microwave absorbers with corrosion resistance should be developed urgently. Herein, a 3D NiAl-layered double hydroxide/graphene (NiAl-LDH/G) composite synthesized by atomic-layer-deposition-assisted in situ growth is presented as an anticorrosive microwave absorber. The content of NiAl-LDH in the composite is optimized to achieve impedance matching. Furthermore, under the cooperative effects of the interface polarization loss, conduction loss, and 3D porous sandwich-like structure, the optimal NiAl-LDH/G shows excellent microwave absorption performance with a minimum reflection loss of -41.5 dB and a maximum effective absorption bandwidth of 4.4 GHz at a loading of only 7 wt% in epoxy. Remarkably, the encapsulation effect of NiAl-LDH can restrain the galvanic corrosion owing to graphene. The epoxy coating with the NiAl-LDH/G microwave absorber on carbon steel exhibits long-term corrosion resistance, owing to the synergetic effect of the superior impermeability of graphene and the chloridion-capture capacity of the NiAl-LDH. The NiAl-LDH/G composite is a promising anticorrosive microwave absorber, and the findings of this study may motivate the development of functional microwave absorbers that meet the demands of anticorrosive performance of coatings.