Surface modification as an effective approach to enhance the microwave absorbing properties of hollow carbon spheres

The microwave absorbing properties of hollow carbon spheres modified by KOH were measured using a transmission/reflection coaxial method in the range of 2–18 GHz. The modification could result in a significant enhancement in the properties, including both the increment in absorbing intensity and bandwidth and the decrease in absorber thickness, which can be well explained by the high concentration of dangling bonds in per unit volume or per unit weight introduced during the modification. This dangling bond dominated mechanism could be used to instruct the design of absorbers with outstanding performances.