Green Synthesis of Porous Cocoon-like rGO for Enhanced Microwave-Absorbing Performances

Abstract

A novel porous cocoon-like reduced graphene oxide (rGO) with high porosity and low density was fabricated by a simple and green reduction reaction using ascorbic acid as the reductant in combination with a freeze-drying process without annealing. The bulk density of porous cocoon-like rGO is only 28.49 mg/cm3, and the porosity reaches 94.57%. The reaction times have an important influence on the formation of porous cocoon-like rGO and the reduction degree of rGO. The porous cocoon-like rGO exhibits an excellent microwave-absorbing property with a low mass filling ratio of 7.0 wt %; its minimum reflection loss (RL) is −29.05 dB at 15.96 GHz with a sample thickness of 2.0 mm and the effective absorption bandwidth (RL < −10 dB) is 5.27 GHz. The microwave-absorbing property of porous cocoon-like rGO is much better than that of GO and other porous rGO. The in-depth analyses of the reduction degree, porosity, and microwave-absorbing performance illustrate that the microwave-absorbing performance of rGO is significantly related to the reduction degree and porosity. In addition, the synthetic route for porous cocoon-like rGO is simple, has low energy consumption, and is environmentally friendly. Our work demonstrates that the porous cocoon-like rGO is a promising lightweight microwave absorber with high performance.

Rational Construction of Hierarchically Porous Fe–Co/N-Doped Carbon/rGO Composites for Broadband Microwave Absorption

“…First, GO was prepared via the modified Hummers method [37]. Second, 1 3 porous cocoon-like rGO was fabricated using our previously reported method [33] (SI). Third, 15 mg of porous cocoon-like rGO was dispersed in 10 mL of methanol and marked as solution A.…”

“…In addition, rGO with a porous structure can effectively broaden the effective bandwidth because the microwaves entering the pores of rGO can be reflected and multiply scattered [31][32][33][34][35][36]. Hence, we introduce the Fe-doped Co-MOF into porous cocoon-like rGO to prepare multicomponent and hierarchically porous Fe-Co/NC/rGO composites.…”

Green Synthesis of Porous Spherical Reduced Graphene Oxide and Its Application in Immobilized Pectinase

“…As shown in Figure 2a, the typical peaks of GO were observed at 3381 cm −1 (O−H stretching vibration), 1728 cm −1 (CO stretching vibrations), 1620 cm −1 (CC stretching of aromatic zooms), 1368 cm −1 (−OH stretching vibrations), 1223 cm −1 (C−O−C vibrations of epoxy groups), and 1053 cm −1 (C−O stretching vibrations). 23 At increased reduction reaction times, the peak intensities of the above oxygen-containing functional groups for rGO decreased gradually.…”

“…Preparation of Porous Spherical rGO. Porous spherical rGO was obtained by the Shanshan Wang method, 23 and the experimental conditions were optimized. The steps were as follows: 30.00 mL of GO (1 mg/mL) aqueous dispersion was sonicated for 60 min.…”

Recent Advances in MXene/Polyaniline-Based Composites for Electrochemical Devices and Electromagnetic Interference Shielding Applications

“…To date, various types of materials have been utilized in preventing EM wave pollution . For metals, copper, aluminum, silver, nickel, and stainless steel have been used as a shield, while these metals have certain limitations, such as high density, difficult machining, and high corrosion susceptibility. , Many heterogeneous composites with conducting fillers (e.g., carbon nanotubes (CNTs), graphene, reduced graphene oxide (rGO), and MoS 2 ), magnetic fillers (e.g., Fe 3 O 4 , Fe 2 O 3 , and barium ferrite), , and dielectric fillers (e.g., BaTiO 3 , TiO 2 , and PbTiO 3 ) ,, have been applied in the EMI shielding application instead of metals because of their advantages (e.g., low weight, better environmental stability, and excellent corrosion-resistant properties). − …”