Self-supported construction of three-dimensional NiCo2O4 hierarchical nanoneedles for high-performance microwave absorption

Abstract

Grafting one-dimensional (1D) structure onto three-dimensional (3D) carbon foam is a practical and novel protocol to improve its microwave attenuation capability. Herein, a unique microwave absorber with NiCo2O4 nanoneedle grew on carbon foam (NCOCF) has been built via a combined approach of carbonization and hydrothermal treatment. The obtained NCOCF exhibit good impedance matching and excellent attenuation capability, which means that the microwave energy can be dissipated through conductive loss, interfacial polarization and multiple-scattering. These advantages result in the effective transformation of microwave energy to heat, thus yielding a remarkable microwave adsorption (with a thickness of 2.8 mm, the maximum reflection loss (RLmax) is −63.6 dB, and the effective absorption bandwidth (EAB) is as wide as 4.72 GHz with a thickness of 1.3 mm). The study would offer a strategy for development of the high-performance microwave absorber.