Enhancing electromagnetic properties in nickel hydroxide modified graphene composites via secondary reactions for improving multi-polarization electromagnetic absorption efficiency

Abstract

Carbon-based materials exhibit excellent dielectric absorption properties, among which graphene has received particular attention in research of electromagnetic wave absorbing materials because of its high electrical conductivity and unique large-area, thin-layer two-dimensional structural features. However, the electromagnetic absorption performance of the material is hindered from further improvement due to its single component composition. It is influenced by the conductive network of graphene, making it challenging to achieve a balance in impedance matching and electromagnetic loss, thereby restricting its broader application. To address these challenges, we developed a series of nickel hydroxide-modified graphene composites. Through a structural composite design, we optimized overall impedance matching, introduced diverse loss mechanisms to enhance electromagnetic loss performance, and utilized a secondary reaction control method to precisely regulate the deposition of nickel hydroxide on the graphene surface, thereby achieving regulate of the composite material's electromagnetic parameters within a defined range. Under low sample filling ratios and a thin sample thickness of 1.8 mm, the effective absorption bandwidth reaches 6.5 GHz, demonstrating excellent electromagnetic absorption performance. This study provides a controllable design approach for modulating material electromagnetic parameters by influencing the reaction process. It also offers a design method for composites with an outstanding electromagnetic loss mechanism.