Preparation of morphology- controllable γ-AlOOH/RGO composites and broadband microwave absorbers

A γ-AlOOH/reduction graphene oxide composite absorbing material with controllable morphology was prepared by controlling the hydrothermal reaction time, and its absorbing properties were studied. The results show that as the hydrothermal time increases, the morphology of reduced graphene oxide-modified γ-AlOOH sequentially grows into vesicle nanospheres, hollow flowers, and flowers, which enhances interface polarization and improves multiple scattering. When the hydrothermal reaction time is increased from 3 to 9 h, the microwave absorption performance of the composite material is significantly improved. Among the prepared γ-AlOOH/reduction graphene oxide composite materials, the sample prepared with a reaction time of 9 h has the best comprehensive performance, with a minimum reflection loss of − 43.3 dB and a maximum effective absorption bandwidth of 7.04 GHz (10.96–18 GHz). When the hydrothermal time is 9 h, the entire Ku band is covered. This work provides a feasible strategy for tuning the microwave absorption properties of γ-AlOOH by changing its morphology.