In-situ synthesis of layered porous coal-derived carbon/Ni magnetic composites with promising microwave absorption performance

A facile in-situ strategy has been developed to synthesize lightweight ultrathin coal-derived carbon-nickel composites (CDC/Ni) with superior microwave absorption performances using anthracite as raw material for the first time. The phase structure and chemical composition were investigated by X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). Field emission scanning electron microscopy (FESEM) images indicate that the surface of the composite is covered with layered stripes and a large number of macropores. Transmission electron microscopy (TEM) images show Ni nanoparticle size from 30 to 80 nm. Since the introduction of magnetic nickel increases the magnetic loss and improves impedance matching, the CDC/Ni magnetic composites exhibit excellent microwave absorption performance. Specifically, a minimum reflection loss of −62.51 dB is observed at 15.76 GHz, with an effective absorption bandwidth of 4.08 GHz, while the thickness is only 1.31 mm. The superior microwave absorption performance is mainly attributed to the suitable conductivity of CDC. The presence of the nickel nanoparticles has enabled to achieve impedance matching. Besides, the special morphology and oxygen-containing functional groups also bring out various loss mechanisms. Therefore, such CDC/Ni composites could be potential lightweight high performance microwave absorbing materials. In addition, our strategy is a cleaner and more efficient process to utilize coals.