Inner Surface-Functionalized Graphene Aerogel Microgranules with Static Microwave Attenuation and Dynamic Infrared Shielding

Abstract

Bulk graphene aerogels with high electrical conductivity, ultralow density, and high specific surface area have attracted significant attention because of their fascinating performances in energy storage, catalysis, absorption, sensor, electromagnetic shielding, etc. However, graphene aerogel microgranules (i.e., reducing the size of the bulk aerogels into microscale) and their performances in the electromagnetic field have been ignored. Herein, we report a new strategy to make floatable graphene aerogel microgranules with high hydrophobicity (137°), low density (13.5 mg/cm), and high specific surface area (516 m/g). These microgranules were synthesized initially from reduced graphene oxide (rGO) hydrogel microparticles and then in situ-modified by silica nanoparticles. Further investigations have demonstrated that the resulting silica-modified rGO aerogel microgranules possess highly efficient static electromagnetic screening (average 30.3 dB in 8-18 GHz) and dynamic infrared shielding (higher than 10 dB during floatation in air for 15 min) properties. The work reported here should give much inspiration to make more functional aerogel microgranules used in various emerging fields.

Electroless Plating of Graphene Aerogel Fibers for Electrothermal and Electromagnetic Applications

“…SE R is related to the impedance mismatching between the free space and shielding material while SE A is associated with dielectric loss and/or magnetic polarization. , SE M occurs at internal of materials and can be attributed to absorption for porous materials . All the above components can be calculated based on the measured S parameters as follows where | S ij | represents the power transmitted from port i to port j .…”

“…29,30 SE M occurs at internal of materials and can be attributed to absorption for porous materials. 31 All the above components can be calculated based on the measured S parameters as follows…”

Assembly of graphene oxide on cotton fiber through dyeing and their properties

“…The back sheet is free of dyed fabric and the infrared light emitted by the human body is converted into heat energy, which causes the surface temperature to rise. The conclusion shows that the addition of GO can change the infrared radiation characteristics of the human body, reduced the infrared emissivity of fabric, and attenuate the energy generated by the infrared radiation of the human body, 21,22 and thereby reducing the probability of the target human body being detected and achieving the stealth effect, especially suitable for processing infrared stealth functional textiles. 3.4.2.…”

High-Performance Microwave Absorption Materials: Theory, Fabrication, and Functionalization

“…However, at the same time, the performance of MAMs containing only graphene are often limited by their poor dispersion and a single loss mechanism . One of the typical samples was reported by Wang and co-workers, where the developed graphene only had the lowest RL of −6.9 dB at the thickness of 2 mm. , Therefore, carrying out the structural design of graphene or using other functional materials to achieve combination, are both effective strategies to improve the wave absorption properties of graphene . In terms of structural design, Chen et al synthesized graphene microflowers (GMFs) by three-step methods of spray drying, prereduction, and thermal annealing, which was compared to the annealed commercial GO (CG).…”

“…76,77 Therefore, carrying out the structural design of graphene or using other functional materials to achieve combination, are both effective strategies to improve the wave absorption properties of graphene. 78 In terms of structural design, Chen et al 79 synthesized graphene microflowers (GMFs) by three-step methods of spray drying, prereduction, and thermal annealing, which was compared to the annealed commercial GO (CG).…”