Metal organic frameworks derived NixSey@NC hollow microspheres with modifiable composition and broadband microwave attenuation

The wide utilization of microwave technology across various sectors such as industrial production, medical treatment and military industry accelerates the development of high-performance microwave absorbing materials (MAMs). In this paper, hollow spherical composites composed of NixSey and nano-porous carbon (NixSey@NC) with abundant selenium vacancies were synthesized via a solvothermal process and high-temperature selenylation. The NixSey@NC composites with varied stoichiometric proportions and adjustable dielectric constants were obtained through manipulation of the pyrolysis temperature and Ni/Se ratios. The presence of abundant selenium vacancies plays a crucial role in improving dipole polarization and the composites demonstrate a minimum reflection loss (RL) of -54 dB (1.8 mm). The optimal absorption bandwidth for the composites could almost cover the whole Ku band with thickness of only 1.67 mm (5.6 GHz, 12.4-18 GHz). Consequently, this research could broaden perspectives and applications of metal selenide for electromagnetic protection.