One-pot synthesis of coal gangue–derived NiCG composite for enhancing microwave absorption

Coal gangue (CG) undergoes rapid resource utilization to assist in the fulfilment of carbon peak and carbon neutralization. Herein, CG–derived Ni–loaded coal gangue composites (NiCG) with suitable microwave absorption (MA) performance are designed and prepared using a facile one-pot method and subsequent annealing treatment. The annealing temperature and precursor solution concentration substantially impact the MA properties. As the annealing temperature rises to 700 ºC, the minimum reflection loss (RLmin) of the NiCG700 is measured to be − 28.5 dB with a coating thickness of 3.0 mm. Moreover, the effective absorption bandwidth reaches 4.7 GHz at a coating thickness of 2.0 mm. The competitive performance of NiCG700 is attributed to the effective coordination of magnetic loss and dielectric loss resulting from Ni particles loading on the CG matrix. Therefore, it has broad prospects as an attractive alternative to lightweight and low-cost absorbing materials. Similarly, it also provides a novel way for recycling CG. [Display omitted] •A new coal gangue-derived matrix has been developed for microwave absorption.•Low cost and environment-friendly processing.•The light-weight absorber is synthesized by the facile one-pot method.•Insightful absorption mechanisms reveal how heterostructure enhances MA properties.