Polypyrrole/NiFe-layered double hydroxide composite as an anticorrosive microwave absorber

Abstract

Microwave absorbing materials applied in the ocean environment should not only hold a strong wave absorption performance but also be capable of resisting corrosion due to seawater. Herein, a polypyrrole@NiFe-layered double hydroxide (PPy@NiFe-LDH) composite was fabricated by combining a hydrothermal process and an electrodeposition method and was applied as an anticorrosive microwave absorber. The results demonstrate that the coating size and thickness of PPy on the NiFe-LDH surface could be easily adjusted by controlling the deposition time, which is of great significance to regulate the wave absorbing and corrosion-resistance performance. Due to the high conductivity of PPy and the obvious physicochemical difference between PPy and NiFe-LDH, a high conductive loss and strong interface polarization loss were achieved for PPy@NiFe-LDH. The optimal PPy@NiFe-LDH shows outstanding absorption properties, including a minimum reflection loss of −59.5 dB at a thickness of 3.8 mm and a maximum effective absorption bandwidth of 5.76 GHz (12.24–18.00 GHz) at a thickness of 2.4 mm. Moreover, multiple protective properties such as the spatial barrier effect, maze effect, and chloride ion capture ability of the PPy@NiFe-LDH coatings lead to their long-term remarkable resistance to acidic, neutral, and alkaline mediums. This study provides novel insights for the exploration of microwave absorbers that simultaneously satisfy the demand for corrosion resistance in the complex ocean environment.