Many traditional electromagnetic protection materials are limited by fixed protection parameters, preventing the passage of both weak electromagnetic information and strong signals from malicious attacks. This cannot meet the current adaptive requirements for electromagnetic protection of high-frequency equipment in the information age. Hence, it is crucial to explore and create a novel self-adaptive and proactive electromagnetic shielding material. ZnO and graphene (GN) composites have attracted attention due to their tunable electrical properties and potential for intelligent protection applications.

This study aims to synthesize and characterize ZnO-coated graphene nanocomposites, with a focus on their nonlinear conductive performance for use in adaptive electromagnetic protection. The goal is to achieve tunable switching behavior through compositional adjustment and microstructural control.

The nanocomposites were synthesized using a solvothermal method. The morphology and distribution of ZnO nanoparticles on graphene were characterized by scanning electron microscopy (SEM). The electrical properties, including nonlinear coefficient and switching thresholds, were measured under varying electric fields.

SEM analysis confirmed the uniform coating of ZnO nanoparticles on graphene sheets. The composites exhibited reversible insulating-conductive transition behavior, with threshold electric fields ranging from 0.19 to 0.53 kV/mm and nonlinear coefficients between 4.01 and 5.44 within the 5–8 wt% mass fraction range. The switching threshold was effectively modulated by adjusting the composite concentration.

The GN/ZnO nanocomposites demonstrate promising adaptive performance with tunable switching characteristics, making them suitable for intelligent electromagnetic protection devices. This study provides a foundation for the design of advanced composite materials for electronic protection systems.