Design and synthesis of porous nitrogen-doped Co@C composites with broadband microwave absorption performance

Abstract

Using simple and low-cost methods to prepare composites with low filling rate and broadband microwave absorption is a research subject with great application value. In this work, we synthesized porous nitrogen-doped Co@C composites by high temperature pyrolysis. Under the action of pore-forming agent KOH, a large number of macropores were formed in the composite, which is conducive to transmission loss of incident wave. In addition, the Co particles obtained by the reduction of carbon can be evenly dispersed in the carbon layer, which is a good solution to the problem of agglomeration and oxidation of magnetic metals. By constantly adjusting the ratio of raw materials, the composite obtained excellent microwave absorption performance. At the filling rate of 10 wt% and the thickness of 2.28 mm, the maximum effective absorption bandwidth (EAB max ) reaches 7.00 GHz (11.00–18.00 GHz). This work provides a new strategy for developing low-cost, low filling rate and broadband microwave absorption materials. • The porous nitrogen-doped Co@C composites were prepared by using KOH as pore-forming agent. • The optimal composite obtained excellent microwave absorption performance at the low filling rate of 10 wt%. • The maximum effective absorption bandwidth of 7.00 GHz (11.00–18.00 GHz) was achieved at 2.28 mm.