## 1 Introduction  
With the popularization of 5G communication, 5G base stations are increasingly distributed. The 5G base station has a higher frequency band, an ultra large bandwidth, more transmitting and receiving antennas, and more complex beamforming working modes compared to 4G applications, which requires increasing power density and integration [1]. This may cause a series of problems. On one hand, a number of digital parts inside the 5G base station, such as high-frequency signal lines, pins of integrated circuits, and various types of connectors, may emit mass microwaves, affecting the normal operation of microwave-sensitive elements inside and outside the 5G station [2, 3]. It may also have an interaction with living species [4]. On the other hand, higher power density generates more heat. This excess heat has difficulty exporting through thermal conduction between electronic components, causing the temperature inside the base station to rise, significantly reducing its operating life [5]. Therefore, the demand for heat-conducting and wave-absorbing materials is growing rapidly. To solve this problem, thermally conductive materials are applied on the surface of electronic components. However, since thermal conductive material already occupies limited space inside of the device gap, there is no space for additional wave-absorbing material [6]. Also, the continuous thermal path required for heat conduction will be drastically reduced once it is blocked by wave-absorbing materials with low thermal conductivity [7]. Therefore, the demand for a material with both heat-conducting and wave-absorbing properties is growing rapidly. Figure 1 shows the typical application and working mechanism of existing wave-absorbing materials in 5G base stations. There are two widely used solutions--one is microwave-absorbing thermal interface material (TIM) [8] by attaching a functional polymer pad directly to the surface of the microwave or heat source so that the heat can be directly transmitted to the shielding and dissipated. The second method is the form-in-place (FIP) sealing gasket [9], which acts in the gaps at bulkhead joints and the gaps at shielding joints to avoid the leakage of electromagnetic waves and the blocking of heat conduction. Leading product providers include Laird Co., Nolato Co., FRD Co., etc. However, existing products either have a relatively low reflection loss of \(-10\) dB with a low thermal conductivity of \(1\ W/(\text{mK})\) or have a high thermal conductivity but with no wave-absorbing ability [10]. A material that combines both properties has yet to be developed. The most widely used packaging materials for the 5G base station are polymer materials, among which epoxy resin attracts attention for its excellent adhesive and mechanical properties. However, epoxy resins have poor thermal conductivity and microwave-absorbing properties [11; 12]. Normally, functional fillers are used in polymer materials to achieve better thermal and magnetic properties. Recently, carbon materials have received extensive attention thanks to their excellent dielectric properties as well as high electrical conductivity, such as carbon nanotubes, graphene, etc. [13; 14; 15; 16; 17; 18]. Among them, graphene oxide has residual defects and an amount of epoxy, hydroxyl, and carboxyl groups on its surface. These factors may result in the transition from contiguous states to the Fermi level, thus proposing an impedance match performance. Moreover, defect polarization relaxation and groups' electronic dipole polarization relaxation are also beneficial for enhancing their wave-absorbing performance [19]. Last but not least, materials with 2D structures, such as graphene and MXene, exhibit excellent thermal conducting and wave-absorbing properties. [PERSON] et al. [20] reported a self-assembly anchored MXene nanosheet loaded with CMWCNTs with a maximum reflection loss of \(-46\) dB at a thickness of \(1.5\) mm.