Three-dimensional nitrogen-doped reduced graphene oxide aerogel decorated with Ni nanoparticles with tunable and unique microwave absorption

Developing microwave absorption (MA) materials with compatible dielectric constant and good impedance matching is a great challenge. Herein, a series of composites with Ni nanoparticles anchored on three-dimensional nitrogen-doped rGO aerogels (N-rGA/Ni) are successfully synthesized with the aid of EDTA. The characterizations confirm that nano-sized Ni nanoparticles are evenly and firmly distributed onto graphene sheets. The calcination temperature affects the graphitization degree, nitrogen doping content, particle size as well as magnetism of Ni nanoparticles, which can direct the dielectric loss and magnetic loss of N-rGA/Nis. Among, N-rGA/Ni(600) manifests the best property with maximum reflection loss (RL) of -60.8 dB at 13.7 GHz, and effective absorption band (EAB) of 5.1 GHz at the layer thickness of 2.1 mm, which is ascribed to its proper dielectric loss and better impedance matching. Products obtained at calcination temperature of 500 degrees C and 700 degrees C also exhibit unique advantages. N-rGA/Ni (500) possesses wider EAB (6.6 GHz) at a fixed thickness (2.4 mm), while the microwave absorption of N-rGA/Ni(700) can reach -47.9 dB even at an extremely thin layer (1.6 mm). These results indicate that the N-rGA/Ni composites can meet different microwave absorption demands and be ideal candidates to be used as multi-role synergistic microwave absorbents. (C) 2019 Elsevier Ltd. All rights reserved.