A hierarchical SiCnw@SiC aerogel decorated with Ni-capped carbon nanotubes toward high-performance electromagnetic wave absorber

•The SiC nanowires-reinforced SiC aerogel by decoration of Ni-capped carbon nanotube with 3D hierarchical microstructure were prepared.•Both multiple dielectric/magnetic losses and good impedance matching capability were achieved.•Less than 30 wt% filler loading and thin thickness of 2 mm are beneficial to obtain lightweight absorbing materials.•A strong RLmin of −47.75 dB and broad effective bandwidth of 8.96 GHz were realized.